Ian West. 2017. Geology of Sidmouth and Ladram Bay, Devon, southern England. Jurassic Coast, UNESCO World Heritage Coast. http://www.southampton.ac.uk/~imw/Sidmouth-Devon.htm. 8th April 2017.
Geology of Sidmouth, Devon

Ian West,

Romsey, Hampshire

and Visiting Scientist at: Faculty of Natural and Environmental Sciences,
Southampton University,

Webpage hosted by courtesy of iSolutions, Southampton University
Aerial photographs by courtesy of The Channel Coastal Observatory , National Oceanography Centre, Southampton.

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Cliffs of Triassic Mercia Mudstone above Otter Sandstone, west of Sidmouth, Devon, 29th September, 2008

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Red Triassic cliffs of Devon, England - view of Ladram Bay, High Peak and towards Sidmouth, 26th September 2009 - unlabelled version

Red Triassic cliffs of Devon, England - view of Ladram Bay, High Peak and towards Sidmouth, 26th September 2009 - labelled version

Big Picket Rock, a sea stack of Otter Sandstone, Triassic,, between Sidmouth and Ladram Bay, East Devon

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[CONTENTS LAYOUT IN PREPARATION]

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CONTENTS:

[Note: Line numbers given, are those of the lines in the large computer code and text of this webpage to assist the writer in finding and organising the location of particular items. All addition and editing is done directly on the code.]


SECTION 1 - INTRODUCTION


1-INT-1. 1-INTRODUCTION - General and Access - [line 575]
1-INT-2. 1-INTRODUCTION - Safety - [line 620]
1-INT-3. 1-INTRODUCTION - Topographic Maps - [line 654]
1-INT-4. 1-INTRODUCTION - Geological Maps - [line 679]
1-INT-5. 1-INTRODUCTION - Strata General [line 712]
1-INT-6. 1-INTRODUCTION - Stratal Succession [line779]
1-INT-7. 1-INTRODUCTION - Cliff Sections [line 873]

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SECTION TWO - STRATIGRAPHY


2-STRAT-1. 2-STRATIGRAPHY - Otter Sandstone Formation [line 872]
2-STRAT-2. 2-STRATIGRAPHY - Sidmouth Mudstone Formation [line 927]
2-STRAT-3. Higher Mercia Mudstone Group - [line 1016]
2-STRAT-4. Cretaceous - Gault Clay Formation [line 1033]
2-STRAT-5. Cretaceous- Upper Greensand [line 1054]
2-STRAT-6. Cretaceous - Chalk[line 1066]
2-STRAT-7. Cretaceous Overstep [line 1086]
2-STRAT-8. Miscellaneous[line 1102]

[done to here, 30th March 2015]

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2-STRAT-3. subject -
2-STRAT-4. subject -
2-STRAT-5. subject -
2-STRAT-6. subject -
2-STRAT-7. subject -
2-STRAT-8. subject -
2-STRAT-9. subject -
2-STRAT-10. subject -

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SECTION THREE - LOCATIONS EAST OF SIDMOUTH [line 953]


3-EASTSID-1. Location - Pennington Point and Salcombe Hill Cliff [line 1131]
[Subsection: Rhizoconcretion breccia: line 1195]
3-EASTSID-1a. Location - Pennington Point and Salcombe Hill Cliff - Seismite (Earthquake Bed) [line 1549]
3-EASTSID-2. Location - Higher Dunscombe Cliff - [line 1227]
3-EASTSID-3. Location - Old Railway Tunnel [line 1328]
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SECTION FOUR - LOCATIONS - SIDMOUTH TOWN AND BAY

4-SIDMOUTH-1. Location - Sidmouth Town - [line 1192]
4-SIDMOUTH-2. Location - Sidmouth Town - Mammoths
4-SIDMOUTH-3. subject - Sidmouth Town - ?
4-SIDMOUTH-4. Location - Jacob's Ladder and Chit Rocks [line 1848]
4-SIDMOUTH-5. subject -

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SECTION FIVE - CLIFFS WEST OF SIDMOUTH


5-WESTSID-1. Cliffs Under Peak Hill (line 1875)

5-WESTSID-2. subject -
5-WESTSID-3. subject -
5-WESTSID-4. subject -
5-WESTSID-5. subject -
5-WESTSID-6. subject -
5-WESTSID-7. subject -
5-WESTSID-8. subject -
5-WESTSID-9. subject -
5-WESTSID-10. subject -

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SECTION SIX - LADRAM BAY


6-LADRAM-1. subject -
6-LADRAM-2. subject -
6-LADRAM-3. subject -
6-LADRAM-4. subject -
6-LADRAM-6. subject -
6-LADRAM-6. subject -
6-LADRAM-7 subject -
6-LADRAM-8 subject -
6-LADRAM-9. subject -
6-LADRAM-10. subject -

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SECTION SEVEN - ICHNOLOGY (FOOTPRINTS)


7-SDM-7-1. subject -
7--7-2. Coram -
7--7-3. subject -
7--7-4. subject -
7--7-5. subject -
7--7-6. subject -
7--7-7 subject -
7--7-8 subject -
7--7-9. subject -
SDM-7-10. subject -

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SECTION EIGHT


SDM-8-1. subject -
SDM-8-2. subject -
SDM-8-3. subject -
SDM-8-4. subject -
SDM-8-5. subject -
SDM-8-6. subject -
SDM-8-8 subject -
SDM-8-8 subject -
SDM-8-9. subject -
SDM-8-10. subject -

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SECTION NINE


SDM-9-1. subject -
SDM-9-2. subject -
SDM-9-3. subject -
SDM-9-4. subject -
SDM-9-5. subject -
SDM-9-6. subject -
SDM-9-7 subject -
SDM-9-9 subject -
SDM-9-9. subject -
SDM-9-10. subject -

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SECTION NINE


SDM-9-1. subject -
SDM-9-2. subject -
SDM-9-3. subject -
SDM-9-4. subject -
SDM-9-5. subject -
SDM-9-6. subject -
SDM-9-7 subject -
SDM-9-9 subject -
SDM-9-9. subject -
SDM-9-10. subject -

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SECTION TEN


SDM-10-1. subject -
SDM-10-2. subject -
SDM-10-3. subject -
SDM-10-4. subject -
SDM-10-5. subject -
SDM-10-6. subject -
SDM-10-7 subject -
SDM-10-9 subject -
SDM-10-10. subject -
SDM-10-10. subject -

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SECTION ELEVEN


SDM-11-1. subject -
SDM-11-2. subject -
SDM-11-3. subject -
SDM-11-4. subject -
SDM-11-5. subject -
SDM-11-6. subject -
SDM-11-7 subject -
SDM-11-8 subject -
SDM-11-9. subject -
SDM-11-10. subject -

SECTION TWELVE


SDM-11-1. subject -
SDM-12-2. subject -
SDM-12-3. subject -
SDM-12-4. subject -
SDM-12-5. subject -
SDM-12-6. subject -
SDM-12-7 subject -
SDM-12-8 subject -
SDM-12-9. subject -
SDM-12-10. subject -

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1 - INTRODUCTION

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1 - INTRODUCTION - 1 - General and Access [correct]

Sidmouth is geologically important for providing excellent exposures of the Triassic, Mercia Mudstone and the junction of this with the underlying Otter Sandstone Formation (of the Sherwood Sandstone Group - major oil reservoir elsewhere).

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The town is a small coastal resort easily reached from the A375 from Honiton. It is also easily accessible from the A3052 from Lyme Regis (further east) or by the A3052 from Exeter (further west). It is not far from other coastal geological localities such as Budleigh-Salterton, Devon or Beer, Devon. There are car parks at both the east and western end of the seafront.

On foot the cliff to the east is immediately accessible across the stream at the eastern end of the promenade. The cliff to the west is best accessed from Jacob's Ladder at Chit Rocks. A low tide is needed for good access to the western part.

Access to Ladram Bay and adjacent coast is from or through the village of Otterton. Ladram Bay has a large holiday caravan park which extends down to the coast. the coastal footpath passes through the seaward side of the camp site. Access to the coast is easy from Otterton by following local roads to the southeast. Then there is a path leading on past Monk Wall to the coastal footpath. This path then gives access to Ladram Bay and on to High Peak if required. It also gives access to a long stretch of coast to the southwest, heading for Budleigh Salterton. Ladram Bay can also be reached from Sidmouth by a walk up and over the summit of High Peak.

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1 - INTRODUCTION - 2 - Safety [correct]

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Sidmouth, Devon, rockfall hazard, with relics of an old rockfall in the foreground and an active rockfall in the distance, raising dust

There is serious risk of rock-fall from the cliffs on either side of the main sea-front of Sidmouth. There has, apparently (press report), been a fatality due to rock-fall at the Pennington Point cliffs, Sidmouth, in 2012. Falls can occur in hot, dry weather (due to shrinkage) in addition to occurring in wet conditions. Avoid, as far as possible, the site of previous falls, where more rocks may descend. They are often marked by fresh debris on the beach. Do not linger at such sites. Keep down on the beach, away from the cliffs wherever possible is advised, although this is not always feasible when studying geology. Beware of being trapped by a rising tide and check tide tables in advance. Low tide is essential if proceeding far to the east or west of Sidmouth. At the top, it is obvious that there is always some risk of falling down cliffs if the top edge is approached too closely.

Take care on high sea-walls and on seaweed-covered rocks. Going on to rock armour can be dangerous. Never hammer chert or flint pebbles or boulders; they give off dangerous splinters at high velocity. Carry a mobile phone and ideally a small torch. Do not necessarily go to any locality unless you are confident that it is safe at the time of your visit. Field parties should make their own risk assessments.

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1 - INTRODUCTION - 3 - Topographic Maps and Aerial Photographs

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An old topographic map of the coast from Sidmouth to Dawlish, Devon, including Ladram Bay, Budleigh Salterton, Exmouth and Dawlish Warren

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The most useful Ordnance Survey map of the area is the following:
Ordnance Survey, Sheet 115, 1:25,000 scale (4cm to 1km), OS Explorer Map: Exeter and Sidmouth, Honiton; showing part of the South West Coast.

Aerial photographs can be seen on Google Earth (with a 2014 map visible at present) and from the Channel Coastal Observatory.

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1 - INTRODUCTION - 4 - Geological Maps

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Part of the geological map of Sidmouth, Devon, 1906 edition

Part of the old geological map of Sidmouth, Devon, 1906 edition, including the area around Ladram Bay, East Devon

Current British Geological Survey map of Sidmouth, Devon, and associated explanatory booklet

The geology of the Sidmouth area is fairly straightforward. The Otter Sandstone (beneath) and the red Mercia Mudstone (above) are the Triassic units. There is a major unconformity at the base of the Albian, with some Gault overlain by a thick sequence of Upper Greensand. Some Chalk lies above, but much of it has been eroded away. Some Pleistocene Clay with Flints and Chert is present on hill tops, lying on a dissolved surface of Chalk. There are thin sheets of colluvium, head, gravel and river-valley alluvium.

Both the old edition and the new edition of the geological map bring out the same main features. The geology of the area is not complicated, and thus the Victorian geological mappers, including Sir Henry de la Beche obtained basically correct outcrops and structures. The old map (1906 Drift, and later reprints) is on the scale of 1 inch to 1 mile. If comparision is made, it appears at first sight, like a simpler version of the 2005 edition, with less information on Drift deposits.

The new map, Sidmouth, Sheet 326 and parts of 340, is a Solid and Drift map published in 2005. This edition is on the scale of 1:50,000 and shows more detail. The general outcrop pattern is the same, but formations are renamed and new subdivisions have been introduced. More faults are shown and their continuation offshore is indicated. There is more information regarding Quaternary deposits and collovium conceals much of the Mercia Mudstone (Keuper Marls on the old map). The geology of the offshore area is shown on the new map but not on the old map. The new map is about twice the size of the old version, partly because deep cross sections are shown beneath the actual map. The stratigraphical columns are more detailed with good (metric) information on thicknesses.

With the map is an explanatory booklet: Edwards, R.A. and Gallois, R.W. 2004. Geology of the Sidmouth District; a brief explanation of the geological map, Sheets 326 and 340 Sidmouth, 30pp, including references.

The new map and explanatory booklet can be obtained from the: British Geological Survey Bookshop.

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1 - INTRODUCTION - 5 - Strata General:

The red Permo-Triassic strata form the foundations of Sidmouth and the area around, including as far east as Seaton and to the west at Budleigh Salterton and beyond. They are continental deposits from the great landmass of Pangaea, dating from about 295-250 for the Permian, and from about 250 to 203 million years ago for the Trias. In general they represent continental, desert and semi-desert conditions. There are aeolian deposits, fluvial sediments and evaporites, including gypsum and halite. They are of typical "red-bed" facies, with some green reduced beds and reduction spots in places.

The cliffs adjacent to Sidmouth provide excellent exposures of Triassic part of the sequence of red beds. East of Sidmouth there are extensive exposures of the Mercia Mudstone (later Trias), with some Otter Sandstone (older Trias) exposed near the River Sid. To the west, the Otter Sandstone is present at Chit Rocks (Jacob's Ladder). Beyond a fault at the steps, the Mercia Mudstone is exposed in the cliffs. Further on, near Peak Hill, the gentle eastern dip brings the sandstone up at the base of the cliff. At the west of the bay the Otter Sandstone forms a series of sea stacks. Permian strata are further west in the Exmouth to Dawlish region. This is a good coast for geomorphology and sedimentary structures, but it is not an easy place for fossil collecting. Some vertebrate remains have been found east of Sidmouth. Upper Greensand and Clay-with-Flints is present at the highest cliff tops both east and west of Sidmouth.

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1. INTRODUCTION - 6 - STRATAL SUCCESSION [correct]

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The simplified list of strata at Sidmouth, top-down, using modern BGS terminology, is as follows:

Chalk
(small basal part only), at the top of the cliffs near Sidmouth, but seen much more fully at Beer, further east.

Upper Greensand
(substantial glauconitic sandstone which oxidises and weathers yellow; contain chert in the upper part).

Gault Clay
(thin)

MAJOR UNCONFORMITY

Branscombe Mudstone Formation
(the upper and substantial part of the red Mercia Mudstone of the Trias; this occurs east of Sidmouth and, of course at Branscombe)

Dunscombe Mudstone Formation
(a thinner part of the Triassic, Mercia Mudstone, and known elsewhere in the country as the Arden Sandstone Formation; it is present in Higher Dunscombe Cliff, east of Sidmouth)

Sidmouth Mudstone Formation
(the lower and substantial part of the red Mercia Mudstone Group of the Trias).

Otter Sandstone Formation

(Upper part of the Sherwood Sandstone Group, a major oil reservoir at Wytch Farm Oilfield; this unit is seen at Ladram Bay and to the west towards Budleigh Salterton)

Budleigh Salterton Pebble Bed Formation
(lower part of the Sherwood Sandstone Formation; not seen at Sidmouth but, of course, at Budleigh Salterton, further west).

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[The stratigraphic terminology of the strata at Sidmouth, as given by the British Geological Survey has had some recent changes, incorporated in the list above. For more details see:
Howard et al. 2008 , given in the reference list below. A summary, based on this reference, is as follows:

Lias Group [i.e. Lower Lias etc at Lyme Regis][at top]
Penarth Group [formerly the "Rhaetic" at Pinhay Bay]
Branscombe Mudstone Formation [upper part of the Mercia Mudstone Group]
Arden Sandstone Formation [known at Sidmouth as the Dunscombe Mudstone Formation.]
Sidmouth Mudstone Formation [lower part of the Mercia Mudstone Group]
Otter Sandstone Formation [upper part of the Sherwood Sandstone Group]
Budleigh Salterton Pebble Beds Formation [lower part of the Sherwood Sandstone Group][at base]

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1. INTRODUCTION - 7 - CLIFF SECTIONS

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Diagrammatic cliff sections from Sidmouth through Beer, East Devon to Seaton and Pinhay Bay, near Lyme Regis (uni version)

Geological cliff section from High Peak near Sidmouth, to Beer Head, Devon

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2 - STRATIGRAPHY

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2-1 STRATIGRAPHY - 1 OTTER SANDSTONE FORMATION [line 870]

(Otter Sandstone Formation, Sherwood Sandstone Group, Trias)

Generalised Triassic stratigraphy for East Devon, including Budleigh Salterton

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An isopachyte map showing stratal thicknesses for the Sherwood Sandstone, the lower and main reservoir for the Wytch Farm Oil Field

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Ripple-bedded, fluvial, Otter Sandstone Formation, Sherwood Sandstone Group, Sidmouth, Devon, photographed in 2016 by Andrew Bennett

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The Otter Sandstone Formation, uppermost part of the Sherwood Sandstone Group at Chit Rocks or Jacob's Ladder, Sidmouth, Devon, and showing large-scale cross-bedding, March 2015

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The Otter Sandstone Formation is exposed in the cliffs west of Sidmouth and dips gently to the east. Parts of it are also exposed at Chit Rocks or the Jacob's Ladder locality, and at Pennington Point, east of Sidmouth seafront.

Up to 210 m were proved in a borehole near Otterton, and the formation is 145 m thick in the Musbury Borehole (Edwards and Gallois, 2004). It consists mainly of reddish orange-brown, weakly to moderately cemented, cross-bedded, fine- and medium-grained sandstone, with subordinate units of conglomerate and mudstone that occur as discontinuous lenses and sheets. The conglomerates are mostly intraformational, mainly less than 0.5 m thick, well cemented with calcite, and are interbedded at regular intervals (1-6 m) within the sequence. The mudstones are mainly reddish brown and up to about 2 m thick. Calcareous concretions are locally common, forming subhorizontal sheets, near-vertical cylinders and nodules. Vertical concretions may have precipitated around plant roots, and complex networks of calcareously cemented plant roots are prominent at many horizons. The sheets may represent cementation around ancient water tables ( Purvis and Wright, 1991).

The lower facies of the Otter Sandstone Formation, probably aeolian, at Budleigh Salterton, Devon, August 2005

Sedimentary structures indicate that the lowest part of the Otter Sandstone at Budleigh Salterton (just west of the district) was deposited as wind-blown sand. Most of the Otter Sandstone was deposited in braided and meandering stream channels with highly variable flow rates in arid or semi-arid environments. Cross-bedding indicates that the rivers flowed from south to north. Fossil vertebrates, including terrestrial reptile and amphibian remains in the sandstones and channel-lag gravels and fish in the mudstones, indicate a Middle Triassic, probably Anisian age (Benton and Spencer, 1995; Spencer and Storrs, 2002).

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2-2 STRATIGRAPHY - 2 SIDMOUTH MUDSTONE FORMATION [line 927]

(Sidmouth Mudstone Formation, Mercia Mudstone Group, Trias)

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The Sidmouth Mudstone Formation, the lowest part of the Mercia Mudstone Group, is exposed in the cliffs on both sides of Sidmouth. The Mercia Mudstone Group is about 450 m thick at outcrop in the district. It consists mainly of the Sidmouth Mudstone Formation below and the Branscombe Mudstone Formation above (Gallois, 2001).

There are some small-scale rhythms in the Sidmouth Mudstone comprising fissile, brownish red mudstone overlain by reddish orange muddy siltstone. Each rhythm probably reflects a change from a wetter to a drier climate. Thin but laterally persistent beds of green mudstone are present, many of which are finely laminated or partially dolomitised. Green strata make up about 45 per cent of the sequence in the highest 19 m of the Branscombe Mudstone, giving rise to distinctive red and green striped beds. Thin beds of siltstone or very fine-grained sandstone occur at a few levels, and thin, fining-upwards beds of fine- to medium-grained sandstone also occur at three stratigraphicallevels in the Branscombe Mudstone. Gypsum is common throughout both formations, and is the dominant constituent of the 10 m thick, Red Rock Gypsum Member of the Branscombe Mudstone.

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2-3 STRATIGRAPHY - HIGHER MERCIA MUDSTONE GROUP [line 927]

(Mercia Mudstone Group, Trias)

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[Text to be added]

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2-4 STRATIGRAPHY - CRETACEOUS - Gault Clay Formation [line 1032]

(Gault Clay Formation )

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[Text to be added]

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2-5 STRATIGRAPHY - CRETACEOUS - Upper Greensand [line 1052]

(Upper Greensand )

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[Text to be added]

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2-6 STRATIGRAPHY - CRETACEOUS - Chalk [line 1071]

(Chalk )

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[Text to be added]

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2-7 STRATIGRAPHY - The Cretaceous Overstep [1086]

(Cretaceous Overstep Westward )

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[Text to be added]

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2-8 STRATIGRAPHY - Miscellaneous [1102]

(Stratigraphy - Miscellaneous )

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[Text to be added]

[END OF 2-STRAT]

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LOCATIONS

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LOCATIONS - 3 - EAST OF SIDMOUTH: [1119]

3-1 Pennington Point and Salcombe Hill Cliff

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N.B. There is significant danger of cliff-fall here. See comments above (in Safety section) and some details below.

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Introduction

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The top of the Sherwood Sandstone Reservoir rock, more specifically the Otter Sandstone Formation, seen at Pennington Point, Sidmouth, Devon, March 2015

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Large-scale cross bedding in almost the top Otter Sandstone Formation, Sherwood Sandstone Group, east of Pennington Point, Sidmouth, Devon, 25th March 2015

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The first exposure of the Otter Sandstone, eastward from Sidmouth, Devon, across the footbridge and down some steps to the beach, seen in 2015 under repair after 2014 storm damage

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Evidence of a previous rock fall at Pennington Point, Sidmouth, Devon, 25th March 2015

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Eastward from the town of Sidmouth, Devon, the small River Sid is crossed by the Alma Footbridge (a monument to the battle of Alma in the Crimean War). There are then (normally) steps down to the low-tide beach. In March 2015 repairs to the bridge and steps were taking place, after storms and major cliff falls near Pennington Point in 2012, 2014 and probably at other dates.
See for example:
Dramatic moment 'thousands of tonnes' of rubble come crashing down on to popular beach in Devon ... just yards from tourists. (Article by Carol Driver for Mail Online - Daily Mail website - published 6th August 2014). Go to the original article online for more information.

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A cliff fall at Pennington Point, Sidmouth, Devon, seen in August 2014, photograph by Tony Lane, New Forest Hampshire and reproduced in the Daily Mail online for 2014

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The landslide at Sidmouth beach was caught on camera by tourist Tony Lane said he heard pebbles start to fall before rocks crashed down. Police warning to avoid section of beach where tourist was killed in cliff fall. A man died after a cliff fall in the area in 2012.
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The junction between the Otter Sandstone Formation of the Sherwood Sandstone Group and the Sidmouth Mudstone of the Mercia Mudstone Group, east of Sidmouth, Devon

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A view from the sea-wall, partly looking down, of the Otter Sandstone and Mercia Mudstone cliffs at Pennington Point, east of Sidmouth, Devon, 25th March 2015

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Sandstones in the cliff at Pennington Point, seen when looking westward towards Sidmouth, Devon, by Ian West, 25th March 2015

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A view of the cliffs east of Sidmouth, Devon, showing the top of the Otter Sandstone and the base of the Mercia Mudstone, 7th November 2013, photograph by Alan Holiday

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Uppermost part of the Otter Sandstone at the eastern cliffs of Sidmouth, Devon, 2008

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The junction of the Otter Sandstone and the Mercia Mudstone of the Trias, photographed at Sidmouth, Devon, by Alan Holiday on 21st February 2014, showing erosion from winter storms

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The top Otter Sandstone Formation descends eastward under the Sidmouth Mudstone, east of Pennington Point, Sidmouth, Devon, 25th March 2015

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Sidmouth-Mudstone-Lamination

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A high cliff of Sidmouth Mudstone, at the eastern end of Salcombe High Cliff, Sidmouth, Devon, shows the parallel bedding in the mudstone

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A joint face in the Sidmouth Mudstone Formation, showing the even bedding, Sidmouth High Cliff, Devon, 25th March 2015

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Landslides and Rock-falls

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Fallen debris from the top of the Otter Sandstone Formation, at Pennington Point or Salcombe Hill Cliff, east side of Sidmouth, Devon, 25th March 2015, with Ian West

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A landslide scar at Pennington Point, east side of Sidmouth, Devon, showing water-flow from probably fissured Sidmouth Mudstone, 25th March 2015

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[Add Gallois Landslide Paper] .

Faulting

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Some faults can be seen in the cliffs from near Pennington Point, Sidmouth and on eastward. The usual faults of the Wessex Basin and adjacent areas are extensional from the Permo-Trias up to the base of he Albian. They are a symptom of basin extension and crustal thinning during the Mesozoic before the Albian. They are stretching features that preceded the break-up of this part of Pangaea, and the subsequent (late Cretaceous) development of the Atlantic Ocean. In very general terms, compressional faults (i.e. reversed faults) are more commonly developed in the Tertiary, during the compressional phase that related to the Alpine Orogeny. However, these comments are broad generalisations and should not be regarded as anything other that.

To consider such structures in perspective, see fig. 2 of Ruffell (1991). He shows a hypothetical cross-section across the western margin of the Wessex Basin, with the "Wessex Basin Extensional Faults" (shown as in the Sherwood Sandstone). One shown below is broadly similar to extensional faults common higher in the succession, as for example, in the Kimmeridge Clay Formation of Dorset (where they have been more studied).

The examples shown here are in the high Otter Sandstone and basal Sidmouth Mudstone Formation, in the Pennington Point area, a short distance east of the River Sid. The main fault planes have been emphasised. There are no fault breccias. In one example there seem to be some minor secondary faults associated with the main fault plane, but actually they seem to have minute or negligible displacements.

An important matter here is the lack of fault breccias. It seems that the sandstone do not easily fragment into small pieces. In addition, and of some petroleum geology significance, is the apparent plastic flow of mudstone, rather than brecciation of mudstone. If this is general it may mean that the seal to Sherwood Sandstone reservoir, at least in some places, is good and not broken by breccia. These are only preliminary comments, though, based only two examples, at the moment. It remains to be seen if this general. The matter may be relevant to any fracking of the top Sherwood Sandstone reservoir in other places.

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An extensional normal fault near Pennington Point, Sidmouth, Devon, with apparent plastic displacement of mudstone, 25th March 2015

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An extensional, normal, fault near Pennington Point, east of Sidmouth sea front, Devon, 25th March 2015, original

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An extensional, normal fault near Pennington Point, east of Sidmouth sea front, Devon, 25th March 2015,monchrome version
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Breccia with Reworked Rhizoconcretions or Rhizoliths

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A general view of the dark breccia bed with mud-clasts and with reworked rhizoconcretion debris in the Otter Sandstone Formation, Sherwood Sandstone Group, Pennington Point, Sidmouth, Devon

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Reworked rhizoconcretions in the apparent top of a bed of breccia, in the uppermost Otter Sandstone Formation, at Pennington Point, Sidmouth, Devon, 23rd March 2015

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Reworked rhizoconcretions or rhizoliths on a bedding plane of a breccia block in uppermost Otter Sandstone, at Pennington Point, east of Sidmouth, Devon, 23rd March 2015

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A surface of the dark breccia at the western end of the Pennington Point cliff section, Sidmouth, Devon, shown with colour emphasised

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Thick, cross-bedded, sandstone units occur in the uppermost part of the Otter Sandstone Formation of the Sherwood Sandstone Group at Pennington Point. In late March 2015 some debris cones of substantial cliff falls (probably of the storms of early 2014) had been eroded away. Thus large blocks of sandstone that had been part of the fallen debris have been cleaned and washed by the sea.

Near the base of the cliff is a darker-coloured bed with large red mud-clasts (or rip-up clasts). The bed seems to be some type of sedimentary breccia, but it has not been studied in detail (as far as the author is aware at present - if there is a record, a reference to it will be added here).

On the upper surface of this bed there is penecontemporaneous debris consisting mainly of broken pieces of rhizoconcretions (ie. carbonate-cemented, root concretions). These are straight or curved fragments of about half a centimetre to a centimetre width and a few centimetres in length. There are also some minute ones, about 1 to 2 mm in width. The rhizoconcretion clasts are not associated with any pebbles or clasts of different rock type. This is not a typical pebble bed. However, it contains debris from erosion and probably indicates an erosion surface. It was only seen in fallen blocks and a search in the cliff was not made to locate it in situ. The fallen blocks have to be from the uppermost part of the Otter Sandstone Formation and near the base of the Mercia Mudstone.

Rhizoconcretions in place are abundant in the Otter Sandstone at Ladram Bay and westward to the river Otter (see further appropriate part of this webpage). They do not seem obvious in situ at Pennington Point, but a thorough search was not made (and they might be present). The major fallen blocks of sandstone do not seem to contain obvious rhizoconcretions in the former root positions, i.e. at right-angles to bedding. No thorough search was made though.

This peculiar clastic breccia will be described further if other information is available. It is obviously important and may represent a major horizon of reworking. It should be noted that there is evidence of penecontemporaneous movement near local faults. There is a thickening of the strata, near the Otter Sandstone - Mercia Mudstone boundary west of Chit Rock or Jacob's Ladder, where there is a fault. (Similarly, the Littleham Mudstone shows some limited thickening towards a fault at Straight Point, Littleham Cove. Penecontemporaneous Permo-Triassic tectonic movement is not unknown.)

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Fish-eye Radioactive Nodules, as at Littleham Cove

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Fish-eye nodules from the basal part of the Sidmouth Mudstone Formation, Trias, Pennington Point, Sidmouth, and similar to radioactive fish-eye nodules in the Littleham Mudstone at Littleham Cove

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Littleham Cove, southwest of Budleigh Salterton is very well-known for its radioactive nodules in red mudstone:

For more information go to the:
Budleigh Salterton Webpage.

The basal part of the Sidmouth Mudstone Formation (Mercia Mudstone Group) is of similar facies to the (older) Littleham Mudstone, except that evidence of evaporites is much more abundant. There are common "potato stones" in the basal Sidmouth Mudstone and these are actually partially replaced nodules of gypsum or anhydrite. These are well-known common objects. In spite of the relative lack of obvious relics of evaporites in the Littleham Mudstone Formation, there are desiccation cracks in red mudstone and there is little doubt that the original environment was also one of salt lakes and sabkhas. The two Triassic formations are in many ways very similar.

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LOCATIONS - 3-1a - EAST OF SIDMOUTH: [1547]

3-1a Pennington Point and Salcombe Hill Cliff - Seismite

Seismite Structures - of Earthquake Origin

[the notes here are preliminary and more information will be added, with reference to previous work]

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A very well-defined seismite bed (earthquake bed) is well-exposed, east of Pennington Point, Sidmouth, under the western part of Salcombe High Cliff. There is development of fissures, syn-sedimentary faulting and, in particular, the characterist ball-and-pillow structure. This may well have been described elsewhere and if it has the record will be added. In any case more information will be given and this is preliminary. Late Triassic seismites are well-known in the Penarth Group at the top of the Trias [Simms, Gallois etc references to be added]

The Sidmouth seismite is somewhere near the Anisian - Ladinian boundary (Middle Triassic). A Triassic seismite has been reported in Germany (see below). This has structures resembling ball-and-pillar.

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Knaust, D. Pinch-and-swell structures at the Middle/Upper Muschelkalk boundary (Triassic): evidence of earthquake effects (seismites) in the Germanic Basin. International Journal of Earth Sciences. 91(2):291-303.
Absract: A limestone bed with synsedimentary deformations is described from the Middle/Upper Muschelkalk boundary (Middle Triassic) of Thuringia, Germany. The deformation structures have an elongated geometry in a preferential N-S to NNW-SSE direction and are several metres across in size. They are similar to ball-and-pillow structures but differ from these by absence of significant loading into underlying beds. Their development is interpreted as a result of bed-internal deformation with bed thickening due to lateral contraction and bed thinning due to stretching. This deformation mechanism is comparable to the one producing boudinage structures, in particular pinch-and-swell structures. The deformation style and size of these structures and their widespread occurrence together with other synsedimentary deformation structures support their interpretation as earthquake-induced structures (seismites). Synsedimentary deformation structures are common features that occur in a narrow stratigraphic unit at the Middle/Upper Muschelkalk boundary in different parts of the Germanic Basin and point to tectonically influenced changes in the depositional regime and basin organization. Further examples of pinch-and-swell structures from the Lower and Upper Muschelkalk suggest that tectonics significantly influenced the sedimentation in the Germanic Basin during Middle Triassic time.

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A seismite or earthquake bed in the basal part of the Mercia Mudstone Formation, part of Salcombe-High-Cliff, Sidmouth, Devon, 25th March 2015

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A probable seismite near the base of the Sidmouth Mudstone Formation, east of Pennington Point, Sidmouth, Devon

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Ball and Pillow Structures, reliable indicators of seismites, due to earthquake activity during deposition of the basal Sidmouth Mudstone Formation, Salcombe High Cliff, east of Pennington Point, Sidmouth, Devon, 25th March 2015

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Small-scale, synsedimentary faulting, in the basal Sidmouth Mudstone Formation, Sidmouth, Devon, probably a seismite structure, 25th March 2015

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Apparent downward injection of mud beneath an alluvial fan, flash-flood sandstone, with imbricate breccia at the base, near Pennington Point, Sidmouth, Devon, 25th March 2015, probably a seismite feature

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Some unusual small scale sedimentary structures (shown above) occur in the basal Sidmouth Mudstone Formation (probably the Sid Member of Gallois). They include a typical example of Ball-and-Pillow Structure. These are parts of a seismite, a contorted bed caused by liquifaction due to earthquake activity. Ball-and-Pillow, in particular is notable structure of this origin, and the others are readily explained as liquifaction structures.

In the broader region there are seismites in the uppermost Purbeck strata at Lulworth Cove, Dorset and in the Eocene strata of Bournemouth and Highcliff, Dorset. A seismite is also known in the Penarth Group of the late Triassic. An overlying graded bed, with some imbricate breccia at the base might be a tsunami bed. The earthquake activity may have had some connection with the end of sand deposition (Otter Sandstone Formation) and the change to mud depositions (Sidmouth Mudstone Formation).

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[See also the following:

Simms, M.J. 2003. Uniquely extensive seismite from the latest Triassic of the United Kingdom: Evidence for bolide impact? Geology. v. 31 no. 6 p. 557-560. By By Michael J. Simms.
Abstract:
A 2-4 m thick seismite, in places overlain by a previously unreported tsunamite, can be traced across greater than 50,000 km2 of the outcrop and subcrop of the latest Triassic (Rhaetian) Cotham Member of the Penarth Group, United Kingdom, an extent unique for the British Phanerozoic. Its consistent thickness, intensity of deformation, and preferred orientations of slump-fold axes indicate a seismic event of M greater than 10 with an epicenter greater than 600 km W or NW of central Britain. The magnitude of the event is incompatible with known terrestrial mechanisms (fault, volcano) but is consistent with a major bolide impact. A short, but unknown, interval separates the top of the Cotham Member seismite from major geochemical and biotic perturbations associated with the end-Triassic extinction, although a direct link between the seismite and these other events remains equivocal. The exceptional extent of "mega-seismites" such as this may prove a useful indicator of previously undocumented bolide impacts.]

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Rip-Up Clasts

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Rip-up clasts of red mudstone in the top sandstones of the Otter Sandstone Formation, Sidmouth, Devon, 25th March 2015

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Evaporite Features

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Anhydrite nodules, like those of modern sabkhas, can have some centripetal quartz replacement and become pototo stones like the example from the Triassic Sidmouth Mudstone, Pennington Point, Sidmouth, Devon

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Silicified enterolithic veins with quarz replacement of gypsum or anhydrite, east of Pennington Point, Sidmouth, Devon, 25th March 2015

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LOCATIONS - 3 - EAST OF SIDMOUTH: [1227]

3-2 Higher Dunscombe Cliff (and beyond)

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A general view of the cliffs east of Sidmouth, Devon, including Salcombe Hill Cliff and Higher Dunscombe Cliff, showing the Sidmouth Mudstone Formation of the Mercia Mudstone Group, with Upper Greensand lying unconformably above, February 2015

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Higher Dunscombe Cliff east of Sidmouth, Devon, showing yellowish weathered Cretaceous Upper Greensand lying unconformably above Triassic Mercia Mudstone, also with the remains of a landslide in 2006

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Part of Higher Dunscombe Cliff and the coast beyond to the east, seen from Sidmouth, Devon, 2015

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The cliff of Higher Dunscombe Hill, east of Sidmouth, seen at a distance from High Peak, west of Sidmouth, Devon

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Sidmouth, a view eastward at low tide of Jacobs Ladder and the cliffs to the east of the town, including Salcombe Hill Cliff, Higher Dunscombe Cliff and on to Beer Head

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A general view to the east at Sidmouth, Devon, showing Salcombe Hill Cliff and Higher Dunscombe Cliff, with Triassic strata overlain unconformably by Cretaceous Upper Greensand

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Veins of satin spar gypsum in Triassic Mercia Mudstone, east of Sidmouth, Devon, more specifically on the eastern side of Dunscombe Cliff, photograph by Angelina Clerkin, Semptember 2016

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Veins of satin spar gypsum in fallen blocks of gypsiferous mudstone from the Branscombe Mudstone Formation, part of the Mercia Mudstone Group, eastern part of Dunscombe Cliff, east of Sidmouth, Devon, photograph by Angelina Clerkin, September 2016

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LOCATIONS - 3 - EAST OF SIDMOUTH:

3-3 Remains of an old Railway Tunnel system in Salcombe Hill Cliff

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An old tunnel in the Sidmouth Mudstone, east of Pennington Point, Sidmouth, Devon, probably part of an old railway system intended to be used for the construction of a harbour at Sidmouth

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For further information on the 1830s proposed railway tunnel system see:

Cliff Erosion exposes Old Railway Tunnel.

[Extract from the above, but see the full article]
"The railway tunnel was dug in the 19th Century to transport rock to form a harbour but, famously, the steam engine was too big to fit the hole and the scheme was abandoned. It was once protected by shingle, but Kay Bagwell said the 1995 sea defences led to the eastern beach being washed out - exposing Pennington Point and putting the eastern town at risk. "The hole has been there a long time but it's opening up," said Kay, who runs Sidmouth Trawlers. "The sea is washing it out." She said it was once at ground level but the lost shingle means it is now above head height...." continues:

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See also:
Sidmouth: a harbour never built. Devon History Society.

"If you walk along the beach eastward from Alma Bridge and look up, you'll see an opening in the cliff. Don't mess with it unless you're a serious speleologist; it's the breached remnants of the Sidmouth Tunnel, a never-used narrow gauge railway tunnel dug behind the cliff face: see The railway that never was and Peter Glanvill Photography for images. Its intended use was to carry stone for the Sidmouth Harbour Company, set up to build a harbour at Chit Rocks (below what is now Connaught Gardens and Jacob's Ladder 1) with two L-shaped piers to be named respectively after Princess Victoria and the Grand Duchess Helena of Russia 2."
[The article continues with more information, and with links to literatue and photographs.]

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LOCATION - SIDMOUTH TOWN

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4-1 LOCATIONS - SIDMOUTH TOWN

Sidmouth - Seafront

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Sidmouth seafront seen from High Peak cliffs, west of Sidmouth, Devon, 2009

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4-2 LOCATIONS - SIDMOUTH TOWN

Sidmouth - Mammoths

Teeth of Mammoth (Elephas primigenius) have been found in the bed of the River Sid half a mile from its mouth Woodward and Ussher (1911). Two teeth of Mammoth were found in clay under Sidmouth Beach by Hutchinson who presented them to Exeter Museum. Tusks, bones and teeth of elephant and rhinoceras occur in all the South Devon valleys from the Exe to Lyme Regis. This is not surprising since these animals were the common inhabitants of Devon, until only about 10,000 years ago, when man and/or climatic changes led to the present, abnormally impoverished mammalian fauna of the region.

Also of interest is the submerged forest, that was found after heavy gales on the foreshore at Sidmouth, opposite the Fort field on the west of the river mouth Woodward and Ussher (1911). Stumps of trees were found at 2.4 metres (8 feet) below high water mark. It is not known whether these represent the remains of the common Neolithic submerged forest which is found around much of the south coast of England. If so, this, of course, would be much younger than the elephant remains.

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4-3 LOCATIONS - SIDMOUTH TOWN

Sidmouth -

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4-4 LOCATIONS - SIDMOUTH TOWN

Sidmouth [ready for future use]

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SECTION SEVEN - ICHNOLOGY (FOOTPRINTS)


7-SDM-7-1. subject -
7--7-2. Coram -

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CLIFFS WEST OF SIDMOUTH

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LOCATIONS:

Jacob's Ladder and Chit Rocks [line 1848]

Jacob's Ladder and promontory, on upfaulted Otter Sandstone, west of Sidmouth, Devon, 29th September 2008

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Jacob's Ladder and the base of the former Chit Rock seen from the cliff top, west of Sidmouth, Devon, 25th March 2015

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An almost north-south fault plane at Jacob's Ladder, Sidmouth, Devon, with upthrown Otter Sandstone Formation seen on the right, the east side, 25th March 2015

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LOCATIONS:

Cliffs Under Peak Hill [line 1875]
(West of Sidmouth and west of Jacob's Ladder)

The western view from the beach walking westward from Jacob's Ladder, Sidmouth, Devon, 29th September 2008, with Dr. Ramues Gallois

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Walking across the bay from Jacob's Ladder to the Otter Sandstone - Mercia Mudstone junction, west of Sidmouth, Devon, 29th September 2008, revised 2015

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Cliffs of Triassic Mercia Mudstone above Otter Sandstone present in part at the base, west of Sidmouth, Devon

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A high cliff of Sidmouth Mudstone Formation, Mercia Mudstone Group, Trias, at Peak Hill, west of Sidmouth, Devon

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Sidmouth Mudstone, part of the Mercia Mudstone, below Peak Hill, west of Sidmouth, Devon, 2008, with Ramues Gallois

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Green bands, some associated with thin sandstone, near the base of the Mercia Mudstone, west of Jacob's Ladder, Sidmouth, Devon, with Dr. Ramues Gallois and his ice axe

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A close-up view of green structures in the basal Sidmouth Mudstone Formation, Mercia Mudstone Group, below Peak Hill, west of Sidmouth, Devon

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Alternations between sandstone and mudstone, approximate base of Mercia Mudstone and top of Otter Sandstone, west of Jacob's Ladder, Sidmouth, Devon

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Fallen red mudstone and green sandstone debris from near the base of the Sidmouth Mudstone Formation, Mercia Mudstone Group, Sidmouth, Devon

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Evidence of a mudslide into a dry wadi channel in Triassic sediments, west of Sidmouth, Devon, 2008

Sinuous green reduction features in red mudstone of the Mercia Mudstone, west of Sidmouth, Devon, 2008

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LOCATIONS: West of Sidmouth

Possible Uranium Mineralisation?

Dark mineralisation just beneath a green-red front in the Trias, west of Sidmouth, Devon, 29th September 2008

Details of possible mineralisation near a green-red front at the top of a fluvial sandstone bed, Trias, west of Sidmouth, Devon, 29th September 2008

About 9.5 km to the southwest of the locality discussed here are the radioactive uranium-vanadium nodules in the Littleham Mudstone (near the Permian-Trias boundary) at Littleham Cove. Higher in the Mercia Mudstone (i.e. about 160 or 170 metres above this level) Gallois et al. (2004) have reported fossil wood impregnated with copper silver and uranium minerals. Shown in the photograph above is some black mineralisation that is slightly radioactive and is occurring just beneath a green-red, reduction front. It is not clear as to whether associated black specs are plant remains. Sidmouth, DevonWoodward and Ussher (1911) recorded plant remains, including a plant stem, at the base of the Sidmouth Mudstone Formation (lower part of Mercia Mudstone) This is where uranium mineralisation might be expected, in comparison with the "roll front" model. The minerals require further study.

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LOCATIONS: West of Sidmouth

The Discovery of Labyrinthodonts under High Peak Hill

Reconstruction of a Labyrinthodont, species of which have been found in the Trias of Sidmouth, Devon

Jaw bone and chevron bone of the Sidmouth Labyrinthodont - Labyrinthodon lavisi, Seeley, found in Triassic sandstones west of Sidmouth, Devon

The following comments about the discovery of vertebrate remains in the upper part of the Otter Sandstone under High Peak Hill, west of Sidmouth were given by Woodward and Ussher (1911):

The outcrop of the Upper Sandstones at the base of the cliff naturally depends upon the scour of the shingle beach. They were found to dip beneath sandy marls at somewhat less than half a mile west of the Chit Rocks. The Sandstones crop out on the cliff, on the slope of High Peak hill (513 feet) at between 200 and 300 yards from the fault at Conger Pool. They are overlain by red sandy marls, mottled greenish, and containing buff, grey, and greenish bands of laminated sandstone, often with ripple-marked surfaces, and with occasional pseudomorphs after rock salt. Between High Peak and Peak Hills the cliff is known as Windgate or Windygate. It is much obscured by slips and debris, and furrowed by rain channels, but by a path to the summit the basement beds of the Keuper Marls may be examined at intervals in vertical section.

In 1875 Dr. Johnston-Lavis [Quarterly Journal of the Geological Society of London, 1876, vol. 32, p. 274] discovered the remains of Labyrinthodon lavisi Seeley, [the Labyrinthodonts were large amphibians with conical teeth with a characteristic convoluted structure] below the western slope of High Peak hill at Picket Rock Cove, in fallen blocks and debris from several beds in the cliff" situated about 10 feet from the top of the sandstone." In this talus Dr. Carter subsequently obtained bone structures of Labyrinthodont affinities, and a fragment of jaw-bone, with teeth. In 1882 Mr. A. T. Metcalfe visited the spot and also found osseous structures. He locates the talus on the beach, in which these remains were found, as directly under" a stile on the brink of the cliff, whence a stratum in the sandstones, somewhat lighter in colour than the rest, may be seen dipping to the east. This stratum is very near the junction with the Upper Marls." Mr. Metcalfe was of opinion that the talus with Osseous structures had fallen from this lighter coloured bed, but adds that the late P. O. Hutchinson had assigned a lower horizon. The diagram mentioned by Mr. Metcalfe is no doubt a replica of a careful coloured section by Mr. Hutchinson, of the Sidmouth coast, dated Oct. 8, 1878, that has been recently presented to the British Association Trias Committee. In this section the Labyrinthodont bed is placed at 100 feet above the talus on the beach, and about 50 feet below the base of the Keuper Marls. Two white bands are shown in the uppermost beds of the Sandstone, and above them, at the base of the Marls, a band containing plant-remains. In talus from this band, at Windygate, Hutchinson obtained a plant stem in May, 1878. Dr. Johnston-Lavis described the ossiferous zone as " nearly hard enough in some places for building purposes, containing here and there masses of marl varying in size from that of a pea to that of a hen's egg." " In these beds," he adds, " ripple marks are very plentiful."

For 40 or 50 feet above the plant-bed at Windygate, Hutchinson's section shows lines of geodes in the marls, containing calcspar [calcite] crystals, and in one of the lower bands crystals of celestine [celestite](sulphate of strontium) had formed on them. Above these he placed the band in which pseudomorphs after rock salt had been found. These latter, however, occur also higher up in thin bands which often display ripple marks."

Fragments of bone have also been found by the Rev. S.H. Cook (1876) in a faulted block of Otter Sandstone, just to the west of the main Otter Sandstone outcrop at Jacob's Ladder (Chit Rock).

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LOCATIONS: West of Sidmouth

Rhynchosaurs, Reptiles of the Triassic Otter Sandstone

Hyperodapedon, a rhynchosaur of the Trias, remains of which have found west of Sidmouth, Devon

A reptile skeleton in the desert - East Devon about 250 million years ago

The remains of Rhynchosaur reptiles have been found in the Otter Sandstone in the Sidmouth to Budleigh Salterton area. At the very bottom of the Otter Sandstone Mr Whitaker found remains of Hyperodapedon. See Whitaker (1869) and (Johnston-Lavis, 1876) . Shown above is a speculative reconstruction of the head of Hyperodapedon (based on a skull inRomer (1955)). East Devon was just a small part of the huge desert and semi-desert of Pangaea during Triassic times, about 250 million to 209 million years ago.

Hyperodapedon (Johnston-Lavis, 1876) is a genus of rhynchosaur, a beaked, archosaur-like reptile. It is also known from the Trias of Elgin, Scotland, the Trias of the Parana Basin, Brazil, the Trias of India etc. It was probably a common land creature of Pangaea at this time (about 230 million years ago).

The records mentioned above are very old and of historic interest. For modern technical information on Rhynchosaurs from the Trias of the Devon Coast see: Hone and Benton (2008), and references therein.

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PART 2 - LADRAM BAY

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6. LOCATION:

LADRAM BAY
Introduction

A topographic and location map of the coast between High Peak, near Ladram Bay, and Otterton Ledge at the mouth of the River Otter, East Devon, showing sites of geological interest

Cliff section showing the Otter Sandstone and Mercia Mudstone in the area of Sidmouth and Ladram Bay, East Devon

Approaching Ladram Bay, East Devon, by the coastal footpath from the southwest, and looking northeast, 26th September 2009

Ladram Bay provides excellent exposures of the Otter Sandstone Formation, the uppermost unit of the Sherwood Sandstone Group. The bay and its surrounding region is a beautiful stretch of coast, with only one site of permanent building development and that is on the cliff top at the centre of Ladram Bay. The natural cliff scene is very impressive with magnificent sea stacks of red Otter Sandstone.

Much of the coast near here can be difficult to access, especially at high tide, but Ladram Bay is easy because there is a direct ramp down to the beach. However, it is not normally possible to walk on ths shore beyond the limits of the beach in a northwest or southeast direction. From Ladram Bay there is a good coastal path over High Peak to the northwest and there is a long coastal path on the cliff southwest towards Budleigh Salterton.

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Ladram Bay, near Sidmouth, Devon, in the Triassic Otter Sandstone, as seen from the stack in southern part of the bay at low tide, 21st March 2014, photograph by Alan Holiday

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Ladram Rock, a sea stack of Triassic Otter Sandstone at Ladram Bay, East Devon, England

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A red Devon rock - a sea stack of Triassic Otter Sandstone, Ladram Bay, East Devon, southern England

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LOCATION:

Ladram Bay - Otter Sandstone - Cross Stratification

The Otter Sandstone Formation of the Sherwood Sandstone Group, central part of Ladram Bay, East Devon, England, 26th September 2009

A general view of the Otter Sandstone Formation, Sherwood Sandstone Group, at the northeastern end of Ladram Bay, East Devon, 26th September 2009

An oil reservoir rock at the surface, Ladram Bay, Devon, - this is the Otter Sandstone Formation part of the Sherwood Sandstone Group, the lower reservoir of the Wytch Farm Oilfield

An oil reservoir rock at the surface, Ladram Bay, Devon, - this is the Otter Sandstone Formation part of the Sherwood Sandstone Group, the lower reservoir of the Wytch Farm Oilfield - PARTIALLY INTERPRETED VERSION

Details of cross-stratified Otter Sandstone Formation, Trias, Ladram Bay, East Devon, 26th September 2009

An oblique view of tabular, climbing cross-lamination in the Triassic, Otter Sandstone at Ladram Bay, East Devon

Tabular cross lamination in a possible flash-flood deposit in the Otter Sandstone, Trias, Ladram Bay, East Devon, 26th September 2009

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LOCATION:

Ladram Bay - Clay Lenses

Clay plugs nnels of the fluvial Otter Sandstone Formation, Sherwood Sandstone Group, Trias, Ladram Bay, East Devon, 26th September 2009

A clay lens, in this case with calcareous gravel, in the Triassic Otter Sandstone, Ladram Bay, East Devon

Red mudstone in a clay lens in the Otter Sandstone Formation, Sherwood Sandstone Group, Trias, Ladram Bay, East Devon

Part of the mudstone lens in the Otter Sandstone at the back of Ladram Bay, East Devon, showing an apparent bulge and an anomalous shape of greenish reduction

A clay lens with multiple green bands in a stack at the north end of  Ladram Bay, East Devon

Details of convolutions in the clay lens at the back of Ladram Bay, East Devon

Clay lenses in a stack of Otter Sandstone near Ladram Bay, East Devon, one of them containing convolutions

A clay lens with a flat base and an eroded top, Otter Sandstone Formation, Sherwood Sandstone Group, near the centre of Ladram Bay, East Devon

Lenses of red mudstone, originally clay, are common in the Otter Sandstone Formation, Sherwood Sandstone Group at Ladram Bay and adjacent areas, Devon. In a sense they represent early temporary appearances of Mercia Mudstone facies. They are very obvious just below the change to Mercia Mudstone

At first sight these mud deposits resemble the fills or plugs of channels and appear to be a type of abandonment facies (they are labelled as "clay plugs" on some photographs but there should be correction to "clay lens"). However, greenish-grey reduced horizons within the red mudstone reveal the details of the bedding. If the clay fill had taken place in quiet water in an abandoned channel, thus forming a true clay plug, then the laminae should be horizontal in relation to bedding. However, this is not the case. The greenish laminae are concave upward and slope up and thin towards the margins of the features. Thus the clay fills are the result of deposition during the influence of some current activity.

Convolutions are present in some cases. This may be the result of liquefaction of the water-saturated clay. Such contortion could occur as a result of earthquake shocks or it may have some relationship to compaction processes. It is not understood at present.

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Ladram Bay - Geomorphology - Cliff Erosion and Beach Features

An overview aerial photograph of Ladram Bay, Otterton and adjacent area,  East Devon, for location purposes

Aerial view of the southern part of Ladram Bay, East Devon, courtesy of the Channel Coastal Observatory

Southern part of Ladram Bay, East Devon, with a beach of rounded flint and chert pebbles and cliffs of red, Triassic, Otter Sandstone

A hanging valley in Ladram Bay, East Devon, showing that coast erosion is so fast that stream downcutting has not kept pace

Beach pebbles of flint and chert at Ladram Bay, East Devon, with a relative rarity of Budleigh Salterton pebbles, September 2009

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LOCATION:

Sandy Cove, Hern Rock and Other Stacks

Sandy Cove and Hern Rock, of Otter Sandstone, to the northeast of Ladram Bay, East Devon, 26th September 2009

A sea stack just northeast of Ladram Bay, East Devon, exposing Otter Sandstone with clay lenses or plugs, September 2009

The coast path ascends from Ladram Bay up towards High Peak Hill. There are some viewpoints from the cliff edge on the way. Sandy Cove and Hern Rock (or Hern Point Rock), a sea stack, can be seen from one or two of these. Sandy Cove is not normally accessible except by boat. In the upper photograph, notice the smaller stack beyond and on the far side of the next cove (to the southeast). That is the stack with clay plugs shown which is shown in the lower photograph taken from the cliff top very close to it.

The Otter Sandstone Formation of the Sherwood Sandstone Group is conspicuously cross-bedded at Hern Rock as elsewhere. In the upper part of the stack some clay plugs can be seen. These are shallow depression of some type filled with clay that is now of a dark red colour. The red colour of the oxidised sediments was probably not the original colour. The semi-arid fluvial sediments were probably originally brown (Sahara Desert colour) and stained by ferric hydroxides (limonite or goethite) but now after burial at moderate temperatures the ferric hydroxide has been converted largely into hematite (ferric oxide). This is a normal process and has been seen to commence in the sediments under a Californian desert. They become redder downwards and can be changed towards a more hematite-rich composition in just a few million years.

The greater development of clay plugs towards the top of the stack may be because the junction of the Otter Sandstone and overlying Mercia Mudstone is not very far above the level of the top of the stack. The cliff-top footpath passes over this boundary shortly before the gate into the forest of High Peak Hill is reached.

A sea stack of Otter Sandstone near Ladram Bay, East Devon

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LOCATION:

Cliffs Between Ladram Bay and the Mouth of the River Otter

The cliff top path between Ladram Bay and the mouth of the River Otter, East Devon

The middle part of Chiselbury Bay with its Chesil-like pebble beach, south of Ladram Bay, East Devon, - an aerial photograph courtesy of the Channel Coastal Observatory

Brandy Head, composed of Otter Sandstone, about halfway between Ladram Bay and the mouth of the Otter, East Devon, October 2009

View from Brandy Head north-northeast towards Twopenny Loaf Rock and Crab Ledge, near Ladram Bay, East Devon

Black Head of Otter Sandstone, seen from Brandy Head looking southwest, coast between Ladram Bay and the mouth of the Otter, East Devon, October 2009

Black Head of Otter Sandstone, seen from Danger Point looking northeast, coast between Ladram Bay and the mouth of the Otter, East Devon, October 2009

Breccia beds and rhizoconcretions in the Otter Sandstone near the base of the cliff at Black Head, between Ladram Bay and the mouth of the River Otter, East Devon, October 2009

View of the cliffs towards Danger Point, northeast of the mouth of the River Otter, near Budleigh Salterton, East Devon

Rhizoconcretions in a palaeosol of the Otter Sandstone at Danger Point, northeast of the mouth of the River Otter, East Devon

The South West Coast Path extends for about 3 km. to the southwest from Ladram Bay to the mouth of the River Otter, opposite to Budleigh Salterton. This path can be reached quite easily from Otterton (Piscombe Lane, Stantyway Farm, Monks Wall area). Study the Ordnance Survey map and you can see that a circular walk is quite easy and is only about 6 or 7 km.

Another direction from which the path can be reached is from near Budleigh Salterton. Note that it cannot be reached directly from the Budleigh Salterton beach at the mouth of the Otter because the river, although narrow, is deep and dangerous to cross, and has strong currents. However, not far away, northeast of Budleigh Salterton, there is a bridge over the River Otter near Kersbrook and South Farm and the footpath can be joined here.

The Coast Path on the peninsula of Otter Sandstone (Sherwood Sandstone, Trias) south of Otterton gives good cliff-top views. However there is no access to the seaward shore on any of the stretch between Ladram Bay and the southern tip near Danger Point. The lack of shore-access is because of vertical cliffs that are not cut by stream valleys, so there is no way down. To study this coast properly a boat would be needed. On the cliff top there are some viewpoints and headlands from which the cliffs can be seen (as in photographs here).

The Otter Sandstone in this stretch of coast can be examined to some extent with binoculars or a telephoto camera lens, but the situation is not ideal. This is unfortunate because this stretch of cliffs exposes the main lower and central part of the Otter Sandstone, whereas Ladram Bay (easily accessible) mostly has the upper part exposed. From the cliff top it is not easy to see if this rather lower part of the Otter Sandstone is much different. Clay lenses seem rare compared to the section in Ladram Bay, but it is not clear whether they really are less common or whether that they are just not easily seen (I only recognised one). It is quite likely that because the rather higher Ladram Bay section contains more clay lenses because it is closer to the Mercia Mudstone sequence above.

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LOCATION:

Mouth of the River Otter, East Side -
Accessible Otter Sandstone Exposure

(See also:
Budleigh Salterton Webpage for continuation from the mouth of the River Otter southwestward.)

We walk down to the mouth of the River Otter, East Devon, from the South West coast path on the eastern side, October 2009

The mouth of the River Otter seen from the eastern side, near Budleigh Salterton, East Devon, October 2009

Spit almost blocking outlet of the River Otter, east of Budleigh Salterton, Devon

The mouth of the River Otter, with a cliff of Otter Sandstone, seen from the end of the pebble spit at Budleigh Salterton, Devon in August 2005 at low tide

A view of the Otter Sandstone Formation, Sherwood Sandstone Group, Trias, mouth of the Otter River, near Budleigh Salterton, Devon, August 2005

Exposure of the lower part of the Otter Sandstone Formation, Sherwood Sandstone Group, Trias, east of the mouth of the River Otter, near Budleigh Salterton, East Devon

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LOCATION:

Mouth of the River Otter, East Side -
Rhizoconcretions in the Otter Sandstone

Branching rhizoconcretions in the lower part of the Otter Sandstone, Mouth of the River Otter, east side, near Budleigh Salterton, East Devon, October 2009

Rhizoconcretions in Quaternary dune sandstone, Akrotir, Cyprus

A small exposure of the basal part of the Otter Sandstone can be easily reached by a path down at the eastern shore of the River Otter near its mouth. You cannot get round from this small riverside exposure to the large Otterton Ledge to the south, and there no further good exposure up the river. It is not normally possible to cross the river to Budleigh Salterton.

This locality is interesting for rhizoconcretions, carbonate concretions around former roots in the Otter Sandstone. They are very well-developed here in a bed just above beach level. They are also present in the outer cliffs near Brandy Point, and at Danger Point as shown in photographs above. See the webpage on Budleigh Salterton for more on Otter Sandstone rhizoconcretions. A photograph above shows Quaternary rhizoconcretions from Cyprus, is shown for comparison. These relatively modern examples are very similar.

A low dry plain in western Qatar with distant escarpments of Dammam carbonates of Eocene age

A desert environment in Qatar with xerophyte plants is shown above. The Triassic environment during deposition of part of the Otter Sandstone may have looked rather like this. However, angiosperm plants (i.e. like the xerophytes shown here) had not yet evolved, and it is not known just what type of vegetation produced these roots.

Fragments of rhizoconcretions penecontemporanously reworked into a breccia bed at a shore exposure east of the mouth of the River Otter, near Budleigh Salterton, East Devon

Breccia with black clasts and reworked fragments of rhizoconcretions, east of the mouth of the River Otter, near Budleigh Salterton, East Devon, 11th October 2009

Another interesting feature of the Otter Sandstone near the mouth of the river is the presence of a dark grey breccia with clasts of quartz. It also contains reworked fragments of rhizoconcretions, showing that the carbonate was precipitated around the roots at an early stage, penecontemporaneously.

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A GREAT HURRICANE HITS SIDMOUTH

View of Sidmouth, Devon, looking west from the red Triassic marls of Salcombe Hill Cliff

The base of Chit Rock west of Sidmouth, Devon, a sea stack destroyed in the great hurricane of November 1824

In November 1824, the "Great Gale" struck Sidmouth. This was the greatest storm in the region since Daniel Defoe's 1703 storm, and may have been a one-in-250 year storm. It was clearly recognised as something resembling the hurricanes of the Carribean, Florida and Gulf of Mexico (i.e like Hurricane Katrina). A naval officer said that the wind was stronger than the West Indian hurricanes (Committee on Scientific Memoranda, 1903). There was significant attack on the cliffs and some very bad coastal flooding at Sidmouth from the combined effect of the waves and the high storm surge (probably about 3 or more metres above high spring tide level). Here are some eyewitness accounts of Sidmouth under storm attack:

Sidmouth, Devon, seen from the west, with a low sea front area, which was badly flooded in the 1824 hurricane

The sea wall and promenade at Sidmouth, Devon, defences against major storms, seen here at low tide

"A violent storm all night, quite a Hurricane! I never heard any-thing at all like it! The whole House shook, and our beds were rocked under us, as if they had felt the shock of an Earthquake! . . . (Nov. 24.) A most aweful scene presented itself to us this morning! Such a storm has not been Witnessed in the memory of man! . . . The sea poured in last night, and has very nearly destroyed the whole of the houses in front of it! The water came up as high as Harris'. The grocers, and people were taken out of their beds at night and conveyed in Boats to a place of Shelter: Everyone has lost something, and some poor people Every thing: never was there such a scene of devastation! All the Cottages under the Cliff were washed away: The Beach Walk is entirely destroyed, and covered with Shingle. Wallis' library is nearly knocked to pieces: and old Chit Rock, that gave its character to the Coast Scenery, is thrown down and nothing but its base remains. The rising of the sea was so sudden, that it almost appears to have been the effect of an earthquake! No language can describe the sad and desolate appearance which the Beach now presents, and the poor sufferers walking about, drenched in water, hardly knowing where to go or what to do, is enough to break one's heart...
I never was more frightened in my, life than during the night. I almost expected the House to have fallen down. . . . It was impossible to sleep. . . . I can hardly attempt to describe my feelings. . . . The noise of the wind was like incessant Thunder, but there was something in it still more aweful and supernatural. It seemed to rage so perfectly without controul-so wild and free that nothing I ever heard before could be at all compared to it."

(Extract from an on-the-spot report from a Sidmouth resident, recorded in a diary and reproduced by Committee on Scientific Memoranda (1903)).

A fairly detailed account was given by P.O. Hutchinson in his History of Sidmouth, part of which was reproduced in Committee on Scientific Memoranda (1903). Here is an extract:

"The Chet-rock stood near the south end of the reef. It was about 40 ft high, much beloved by the fishermen as on steering in it was the first mark they made. Annually one of them was crowned as its king. At low tide he and his court marched out and scrambled to its top where they waved their caps, cheered, and drank to the King of Chet (including the King of England) in smuggled brandy. Along the reef extended a labyrinth of stakes and nets called the 'Ram's horn'. At 8 a.m. on Tuesday, 22nd November the glass stood at 29.49. It was new moon, and the tide high at 11.45 a.m. The afternoon was fine and calm but freshened towards evening and the glass sank to 28.25. Mr. Stone, grocer Market place had a party, but it began to rain and blow from S.W. so that he offered them shake-downs. But they bundled on old shawls etc and left. There was only rainwater in the street then. So many slates were blown off he could not sleep and at 4 a.m. found his ground-floor full of water to the knees. He began clearing the shop but the enemy reached his armpits and washed papers off the mantelpiece. J. Pile, ironmonger (now Selleks) in Fore St. saw it full of water and a door wash past. A bag of nails was rusted into a solid mass. Mrs. Mogridge 7 York Terrace found boats etc battering her wall, and bored through a partition into No. 6 for escape. Lodgers at Mr. Pursey's (Canister House) were much distressed. A sick lady had to be taken from a warm bed into a wet boat. The York was much injured. Mr. Hall draper (now Fields) saw sailors, row across the Market-place and rescue ladies from (Pepperells) opposite. The cottagers under Clifton-place escaped to the top 10 min before the houses were washed away. Wallis Library (now the Bedford Hotel) had its Billiard-table broken against the fire-place, and a piano washed into the sitting room. The children were lowered into a drifting boat at the back by blankets - one by mistake into the water, of which he informed them in loud tones. May (gardener) saw it flow up to High St. (now Veales) where it was met by a land-flood and a boat rowed up Old and round into New Fore St. The landlord of the London Hotel saw a specially big wave about 5 a.m. burst in the door of the chemist (now Penberthys) sweep round the shop and reappear laden with bottles & pill-boxes. Edmondson of Bond St. had opened a shop for costly silks in Marine-place and the ball's were found all over the town next day. Mr. Yeates at dawn dragged himself by the railings to the beach, and to his dismay Chet-rock was no longer to be seen. The familiar old mass had been knocked over in the night. Fragments lay about on the reef for two years after. A subscription of 3000 pounds was raised for the sufferers of which Honiton gave the noble sum of 600 pounds.

I only arrived in January 1825 but the most beautiful watering-place of England looked still like a bombarded city. A cart was backed against Marlborough place and men were shovelling pebbles out of the windows into it. A naval officer said the wind was stronger than West Indian hurricanes. The effects long remained. The shrinkage of population (as shown by Registrar's return) and of popularity were due partly to the growth of Torquay, but more to this catastrophe. Depression weighed on our trade for 40 years till it slowly began to revive about 1865. Mr. Hubert Cornish's view of the Rock is inaccurate. It was more like Great-picket."

Some further details of events here have been given elsewhere:

".. the great storm at Sidmouth, and of the conduct of the excellent Mrs. Partington on that occasion. In the winter of 1824, there set in a great flood upon that town -- the tide rose to an incredible height - the waves rushed in upon the houses, and everything was threatened with destruction. In the midst of this sublime and terrible storm, Dame Partington, who lived upon the beach, was seen at the door of her house with mop and pattens, trundling her mop, squeezing out the sea-water, and vigorously pushing away the Atlantic Ocean..."

( The Project Gutenberg eBook, Sydney Smith, by George W. E. Russell). (The futility of the Sidmouth resident trying to mop back the sea was used by writer Sydney Smith as an example of the futility of trying to stop the reform of Parliament.)

See also: Sidmouth Storm of 1824 in: Devon-L Archives. By Robert J. Newton. The extract below is taken from the book "A Story of Sidmouth", by Anna Sutton [1973] (ISBN 0 85033 113 7).

"At 4 o'clock in the morning of 23rd November, 1824, a storm of such violence occurred that the family of Bolt, occupying one of the cottages on the shore, had to seek shelter in the house above. Very shortly after, the cottages were swept away.
As the day dawned, an appalling sight presented itself. The gardens in front of the houses were laid bare and covered with shingle. .."
[continues]

Fisherman's cottages under the cliff at the west side of Sidmouth near Chit Rock which were washed away at the time of the 1824 storm and are shown in an etching of 1815 reproduced by Devon Library and Information Services - Local Study Service. It was out of these cottages that the occupiers escaped up the cliff with their pig.

A hundred years later, in 1924, severe weather washed away much of the shingle from the protective shingle beach and breached the sea wall. Thus, the town was flooded again in that year (Sidmouth Museum, 2000), probably at the same date as Chiswell, on the Isle of Portland, was flooded (see Chesil Beach storm webpage).

In many respects Sidmouth resembles West Bay or Bridport Harbour. This is also a low naturally-reclaimed estuary separated from the sea by a shingle beach and occasionally flooded in the past. At both places there has been historic removal of shingle material from the beach. At both there has been replenishment of the beach in recent years by adding shingle. Inevitably, the one-in-250 year hurricane will eventually return. It remains to be seen whether the Sidmouth sea-wall is high enough to prevent flooding from a several metre storm surge coming up the English Channel. In addition there is the problem of rising sea level. This effect, though, is steady and progressive and is more damaging in the long term. It is the sudden occurrence of a major hurricane that is a continuing risk in both short and long term. It might not happen for a hundred and fifty years, or it could appear next November. Fortunately many buildings in Sidmouth are on higher ground above possible sea-flood level. Given good luck, when the hurricane happens the sea-wall might by then be a very high and rock-faced embankment.

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ERRATICS AND SARSENS

Salcombe Hill

Silicified breccia and sandstone at Salcombe Hill, Devon, have attracted attention because they seem to be sarsen stones at or near their location of origin. Here is some description and comment summarised by Woodward and Ussher (1899).

"Attention was first drawn by Buckland to the occurrence of "pebbles of fat quartz" on the uplands; also to the presence of rounded pebbles of chalk flint, and near Sidmouth of "large blocks of a siliceous breccia, composed of chalk flints united by a strong siliceous cement, and differing from the Hertfordshhe pudding-stone only in the circumstance of the imbedded flints being mostly angular, instead of rounded as in the stone of Hertfordshire." He therefOl'e inferred "that there was a time when the chalk covered all those spaces on which the angular chalk flints are at this time found"; and that there is also reason to think that the plastic clay formation was nearly coextensive with the chalk."

Large blocks of this siliceous breccia may be seen on Salcombe Hill, and beach pebbles formed of it are polished and sold as " Sidmouth pebbles." The occurrence of beds of Tertiary age was discussed by Godwin-Austen (1822 and 1826 - Transactions of the Geological Society), who commented on the occurrence of siliceous breccia near Sidmouth:

"This breccia affords proof of a long post-Cretaceous period of tranquil deposition, and of a subsequent one of destruction, of both of which it is the sole remaining indication. "Besides the breccia, there are large slabs composed partly of similar materials, and in part (taking the blocks according to their thickness) of a compact, fine-grained sandstone, some blocks containing only an occasional flint, but some none at all, in which cases they are mineralogical greywether sandstones; and may probably be the equivalents of those siliceous masses, warranting, a presumption at least, that Tertiary deposits once extended wherever this breccia now occurs; for the blocks are so angular that they cannot be supposed to have been conveyed from a distance."

There was a report on these sarsen stones at Salcombe Hill, regarding a field excursion led by Woodward and Ussher (1899).

"April 1st 1899. - Leaving Seaton soon after 9 a.m., the members were driven along the new Beer road and across the plateau of Chalk and Upper Greensand, by Stovar Long Lane to Holy Head ,419 ft.), and past Hangman's Stone (479 ft.), to the top of Salcombe Hill (557 ft.). Here, alighting from the vehicles [horse-drawn carriages], they took the track leading by South Down Farm towards the brow of the cliffs. Attention was arrested by some large blocks of siliceous breccia, and these were presumed to be relics of former Eocene deposits which once spread across the area, and to which further reference was subsequently made. Long ago Mr. Godwin-Austen remarked on the resemblance of these blocks to greywethers ... The included fragments were angular, but, as Mr. Clement Reid had shown, the materials forming the Bagshot gravels were more and more angular as they were traced westwards.." [continues]

See also Bristow on sarsens at north of the Bovey Basin, Devon.

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ERRATICS AND SARSENS

Boulders, Salcombe Fishing Grounds, English Channel

Hunt (1880, 1881, 1883, 1885) found a considerable number of foreign blocks in the Salcombe fishing grounds, some 30 to 50 km south of the Devon coast. Of 40 blocks described, there is granite, microgranulite, serpentine, syenite, gabbro, diorite, basalt, "diabase" (dolerite), trachyte, gneiss, quartz grit, conglomerate, sandstone and chalk flints and other rock types. They are discussed further by Prestwich (1892). The serpentine is precisely like the Cornish varieties. Surprisingly the other igneous rocks could not with certainty be ascribed to the English or French coasts. The gneiss resembled Hebridean gneiss from Scotland.

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ACKNOWLEDGEMENTS

I am particularly grateful to Dr. Ramues Gallois for information and guidance in the field in the early stages of developing this webpage. The photograph of the silificied tree fern Tempskya is thanks to the finder of this unusual pebble - Rita Morgan. I appreciate the chance to use her photographs and for information on the discovery. Alan Holiday is thanked for photographs of the cliffs east of Sidmouth and at Ladram Bay. Photographs of Sidmouth by Andrew Bennett in Februaryy 2015 are much appreciated and thanks are also due to Andrew for discussing the eastern Sidmouth geology in the field. Andrew has contributed additional photographs. I thank Angelina Clerkin for very kindly donating some photographs of satin spar gypum in the cliffs east of Sidmouth.

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APPENDIX

East of Sidmouth - Tree Fossil -
From Weston Mouth

A pebble of silicified, presumably Cretaceous, Tempskya, from Weston Beach, east of Sidmouth, Devon, found by Rita Morgan

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Now go west to:

Budleigh Salterton?

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BIBLIOGRAPHY AND REFERENCES

See also:
Bibliography of Petroleum Geology of the South of England, particularly with reference to the Sherwood Sandstone reservoir rock at the Wytch Farm Oilfield.


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Ambrose, K., Hough, E., Smith, N.J.P., and Warrington, G. 2014. Lithostratigraphy of the Sherwood Sandstone Group of England, Wales and southwest Scotland. British Geological Survey Research Report, RR/14/01, 50 pp.


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Bateson , J.H. (compiler) 1987. Geochemical and geophysical investigations of Permian (Littleham Mudstone) sediments of part of Devon. British Geological Survey Mineral Reconnaissance Programme Report, No. 89.

Bateson, J.H. and Johnson, C.C. 1992. Reduction and related phenomena in the New Red Sandstone of south-west England. British Geological Survey Technical Report, WP/92/1.


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BBC. 2011. Sidmouth Residents' Plan to Save Cliff Homes from the Sea Withdrawn.
Plans to protect 12 properties from falling over an eroding cliff edge in Devon have been withdrawn. Twelve homes are said to be losing land at up to 4m (13ft) a year because of erosion at Pennington Point, Sidmouth. Residents of Cliff Road applied for a 210m - long wall of boulders to be built at the cliff base. East Devon District Council recommended rejecting the plans but at a meeting suggested a working group be set up to find a better solution. The original plans were then withdrawn by the applicant and a working group involving the local community set up to consider the best options to protect the area. Committee chairman Mark Williamson said he "had a great deal of sympathy for the residents but that the committee had to consider the best interests of Sidmouth overall".
The Cliff Road residents calculated that due to the speed of the erosion the first of their homes could be claimed by the sea within 15 years. They proposed that 5m-high boulders, at a cost of 900,000 pounds should be placed along the base of the cliff to prevent waves from pounding it. Paul Griew who submitted the plans said: "I would have liked them to have supported the application fully. We managed to get people worked up enough to agree to take action now, but they said it was not the best proposal to get the results needed, and this gives them time to do this. We're going to keep pushing... [continues]


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Benton , M. J, and Spencer, P.S. 1995. Fossil reptiles of Great Britain. Geological Conservation Review Series, No. 10. (London: Chapman and Hall.)

Benton, M.J. 2011. Archosaur remains from the Otter Sandstone Formation (Middle Triassic, late Anisian) of Devon, southern UK. Proceedings of the Geologists' Association, vol. 122, pp. 25-33. By Michael J. Benton, University of Bristol, Bristol, BS8 1RJ.
A new jaw from the Middle Triassic (Anisian) Otter Sandstone Formation of Devon confirms the existence of a derived archosaur (avesuchian). Numerous isolated teeth and vertebrae had already suggested the presence of archosaurs in the Otter Sandstone Formation, presumed predators on the fauna of temnospondyls, procolophonids, and rhynchosaurs, but the new fossil is the first to show some diagnostic characters. Other elements in the same block as the jaw, but not necessarily from the same animal, include a possible skull or pelvic bone, a slender long bone, a small tooth (perhaps prolacertiform), and two presumed archosaur dermal scutes. An additional scute is present, as well as the probable distal end of a pubis, perhaps from a large poposaurid archosaur like the Anisian-age Bromsgroveia or Arizonasaurus. The jaw and pubis represent animals of very different sizes, some 0.8m and 3m long in estimated body length respectively.


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Bowman , M.B.J., McClure, N.M. and Wilkinson, D.W. 1993. Wytch Farm oilfield: deterministic reservoir description of the Triassic Sherwood Sandstone. In: Parker, J.R. (ed), Petroleum Geology of Northwest Europe: Proceedings of the 4th Conference. The Geological Society, London, 1513-1518.
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British Geological Survey . 2005. England and Wales, Sheet 326, Sidmouth, Solid and Drift. 1:50,000 Series, British Geological Survey, NERC. Original geological survey at 1:63,360 scale on One-Inch Maps 21 and 22 by De La Beche, CB, F.R.S. Resurved on the One-Inch Old Series Maps by H.B. Woodward, W.A.E. Ussher and C. Reid, 1873-6 and the geology transferred to the New Series Maps with additions by A.J. Jukes-Browne, in 1894-5. Published with drift, 1906. Reconstituted from the one-inch scale without geological revision and reprinted onto the 7th Series One Inch base at 1:50,000 in 1974. Surveyed at 1:10,000 scale by R.A. Edwards, R.W. Gallois, R.J.O. Hamblin, R.A. Ellison, A. J. Newell and A.C. Popple between 1987 and 2000. P.J. Strange, Regional Geologist, Seismic interpretation by S. Holloway. Marine Geology by C.D.R. Evans and N.P.J. Smith. Published 2005. David A Falvey, Ph.D. Executive Director, British Geological Survey.

British Geological Survey (BGS): Woods, M.A. 2011. (compiler). Geology of South Dorset and South-East Devon and its World Heritage Coast.
Special Geological Memoir for 1:50,000 geological sheets 328 Dorchester, 342 West Fleet and Weymouth and 342/343 Swanage and parts of sheets 326/340 Sidmouth, 327 Bridport, 329 Bournemouth and 330 Newton Abbott. Compiled by M.A. Woods. By Barton, C.M., Woods, M.A., Bristow, C.R., Newell, A.J., Westhead, R.K., Evans, D.J., Kirby G.A., and Warrington, G. Contributors: Biostratigraphy - J.B. Riding; Stratigraphy - E.C. Freshney; Economic Geology - D.E. Highley and G.K. Lott; Engineering Geology - A. Forster and A. Gibson. British Geological Survey, Keyworth, Nottingham, 2011. 161 pp. This is the new version of the Geological Survey Memoir for the Dorset Coast etc. and replaces Arkell (1947) and the earlier memoir by Strahan (1898). It covers a wider area than these old memoirs, though, and includes all of "Jurassic Coast", UNESCO World Heritage Coast. It is a key reference work and easily obtainable.

British Geological Survey. 2015 (?). Rock fall at Pennington Point [east of Sidmouth]. Webpage: Rock Fall at Pennington Point. [with spectacular photographs of a rockfall in progress]/
Active coastal landsliding at Pennington Point was caught on camera by local resident, Eve Mathews, showing a dramatic series of rock falls onto the beach. Pennington Point lies just east of the town of Sidmouth on the south-east Devon coast.... Falls began to take place began in February 2009 and continued during March...... Landslides along this section of coast are common; another fall occurred nearby at Hangar Point around the same time...... Pennington Point lies close to the boundary of the Otter Sandstone Formation (part of the Sherwood Sandstone Group) and the Sidmouth Mudstone Formation (part of the Mercia Mudstone Group). The Otter Sandstone Formation forms continuous coastal exposures from the River Otter and is predominantly a sandstone with conglomerates and mudstones. The overlying Sidmouth Mudstone Formation comprises red mudstones. ....

Carter, H.J. 1888. On some vertebrate remains in the Triassic stratas of the south coast of Devonshire between Budleigh Salterton and Sidmouth. Quarterly Journal of the Geological Society of London, vol. 44, pp. 318-319.
In August last my attention was particularly called by the late Dr. John Millar, F.G.S., to the microscopic structure of the remains noticed by Mr. Metcalfe under No. 11 in his paper "On the further discoveries of vertebrate remains in the Triassic strata of the south coast of Devonshire. [published in QJGS, vol 40, p. 257]. These are small pellet-like amorphous bodies averaging from a half to a quarter of an inch in diameter, composed of white crystalline matter, traversed in all directions by semitransparent crystalline plates, showing bone-structure. These pellets occur plentifully in the fallen blocks of Triassic rock on the beach which contain the remains of Labyrinthodonts etc. Dr. Millar remarked that they very much resembled coprolites and were identifical in appearance with some in his possession from the Lias, which he would send me for comparison. ... continues.
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Cook, S.H. 1876. [Bone fragments in the Otter Sandstone Formation near Chit Rock, Sidmouth]. Quarterly Journal of the Geological Society, vol. 32, p. 277.


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Coram, R.A. and Radley J.D. 2012 or 2013. A chirothere footprint from the Otter Sandstone Formation (Middle Triassic, late Anisian) of Devon, UK Proceedings of the Geologists' Association, London, vol. ..pp. .... By Robert A. Coram and Jonathan D. Radley.
Abstract:
The Middle Triassic (Anisian) Otter Sandstone Formation of Devon is well known as a source of vertebrate skeletal remains, particularly of reptiles. Here we report the first definite vertebrate trace fossil, a well-preserved chirothere footprint of uncertain taxonomic identity. Chirothere prints are mostly attributed to rauisuchian archosaurs, probable fragmentary remains of which have previously been recovered from the Otter Sandstone Formation.

Coram, R.A. and Radley, J.D. 2015. Chirothere Footprint Sites from the Otter Sandstone Formation (Middle Triassic, late Anisian) of Devon, United Kingdom. Ichnos: An International Journal for Plant and Animal Traces, 22:1, pp. 29-42. Publisher Taylor and Francis. Available from Informa limited. With locality maps, vertical section, large-scale footprint maps and photographs and drawings of footprints. With 43 references in the reference list.
By Robert A. Coram, (British Fossils, Dorset) and Jonathan D. Radley (School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, UK)
Abstract:
Three chirothere footprint sites are documented from the Middle Triassic (Anisian) fluvial Otter Sandstone Formation of Sidmouth, Devon, UK. One site, on the foreshore below Peak Hill, has revealed numerous tracks, including a probable manus imprint, which are recorded here. Another site, also beneath Peak Hill, has produced a single probable manus track from a higher horizon. The third site, on the foreshore below Salcombe Hill Cliff, has yielded a small number of pes tracks similar to those from Peak Hill. The footprints at all sites are interpreted as belonging to a large Chirotherium ichnospecies, perhaps C. barthii. Kaup. Unusually, the tracks are preserved in mudstone, often in convex epirelief, and are inferred to have been generated subaqueously. The apparent restriction of the footprints to the higher part of the Otter Sandstone Formation supports other evidence, such as a greater abundance of vertebrate skeletal material, subhorizontal rather than vertical rhizocretions, and a greater frequency of lacustrine facies, for a less arid climate and higher water table than lower in the sequence.
[Further notes from the paper: As reported in the abstract, above, footprints were found by the authors at three localities: Peak Hill Site A, Peak Hill site B (both SW of Sidmouth) and at Salcombe Hill Cliff, beyond Pennington Point, east of Sidmouth. All were found in the Pennington Point Member, the uppermost part of the Otter Sandstone Formation. Very good examples of relatively large, five-toed, clawed footprints were found at these localities. The tracks of Chirotherium are probably those of a crocodile-line "rauisuchian" archosaur. They may have been facultative or obligatory bipeds. Some evidence is that pedal (ped) traces are more common than the smaller manus traces. Associated with the tracks in strata above and below are subhorizontal rhizoconcretions. Associated with the rhizoconcretions are small gypsum-lined geodes, relics of gypsum or anhydrite nodules, like those of present day, Arabian Gulf and North African localities (ref to West).]


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De la Beche , H.T. 1822. Remarks on the geology of the south coast of England from Bridport Harbour, Dorset to Babbacombe Bay, Devon. Transactions of the Geological Society, London, series 2, vol. 1, pp. 40-47.
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Dorset County Council. 2000. Nomination of the Dorset and East Devon Coast for Inclusion in the World Heritage List. 149 pp. By Dorset County Council, Devon County Council and Dorset Coast Forum, June 2000, with the help of various contributors. Published by Dorset County Council on behalf of Dorset County Council, Devon County Council and Dorset Coast Forum. Publication of this nomination has been supported by English Nature and the Countryside Agency, and has been advised by the Joint Nature Conservation Committee and the British Geological Survey.
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Dranfield , P., Begg, S.H. and Carter, R.R. 1987. Wytch Farm Oilfield: reservoir characterisation of the Triassic Sherwood Sandstone for input into reservoir simulation studies. In: Brooks, J. and Glennie, K. (eds), Petroleum Geology of North West Europe, Graham & Trotman, London, 494-503.
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Durrance , E.M. and Laming, D.J.C. (Editors) 1982 (reprinted 1985, paperback, and 1993). The Geology of Devon. University of Exeter Press. 346 pp. ISBN 0 85989 247 6. "Preface: Geological Field Work: It has often been remarked that geology is a subject best studied by actually looking at rocks, minerals and fossils, and their structures and relationships, in the field. Therefore, although this book mainly deals with descriptions from an interpretative viewpoint, at the end of each appropriate chapter a number of localities are listed which will serve to illustrate the main points dealt with in the text. The localities are mainly arranged in subject groupings, although some geographical subdivision is also present. Excursions to specific areas of Devon, to include visits to a number of sites of different character, may thus be constructed with the aid of the appropriate Ordnance Survey and Geological Survey maps, according to individual requirements.
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Edwards R. A., Warrington, G., Scrivener, R. C., Jones, N. S., Haslam, H. W., and Ault, L. 1997. The Exeter Group, south Devon, England: a contribution to the early post-Variscan stratigraphy of northwest Europe. Geological Magazine, Vol. 134, 177-197.

Edwards, R.A. and Gallois, R.W. 2004. Geology of the Sidmouth District: a brief explanation of the geological map. Sheet Explanation of the British Geological Survey. 1:50,000 Sheets 326 and 340 Sidmouth (England and Wales). NERC 2004. Keyworth Nottingham: British Geological Survey. 30pp. Obtainable from BGS, British Geological Survey Bookshop, online.

Edwards, R. A., and Scrivener, R. C. 1999. Geology of the Country around Exeter. Memoir of the British Geological Survey, Sheet 325 (England and Wales).


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Egdon Resources Plc. 2006. Portland Gas Storage Project Update, 28th June 2006. Available online.
Egdon Resources Plc (AIM : EDR), the onshore UK focused energy company, today provides an update on its gas storage project on the Isle of Portland in Dorset. Portland Gas Limited (Portland Gas), a wholly owned subsidiary of Egdon Resources Plc, is pleased to report that drilling operations for the Portland-1 borehole have been completed and the BDF Rig 28 is expected to be released within the next 24 hours. A total drilled depth of 2929 metres was reached in the Triassic Sherwood Sandstone on 21st June 2006. The Portland-1 borehole on the Isle of Portland, Dorset was drilled to confirm that a halite sequence with a low insoluble content (called S7 by Portland Gas), within a Triassic salt sequence (Saliferous Beds) of the Wessex Basin, was suitable for the creation of caverns to store natural gas. Initial technical analyses of the data acquired from the borehole, by Portland Gas consultant DEEP. Underground Engineering GmbH (DEEP) of Germany, indicates that individual caverns of approximately 250,000 cubic metres could be created within the S7 sequence at the Isle of Portland location. This is the same volume used in the pre-feasibility work for the project prior to the drilling of the Portland-1 borehole. The Saliferous Beds were encountered with a thickness of 470 metres (41 metres thicker than forecast). The top of the target S7 interval was penetrated at a depth of 2365 metres and was found to have a thickness of 135 metres (43 metres thinner than forecast). DEEP will coordinate the completion of further laboratory work on core samples over the S7 sequence and computer simulation of the proposed cavern leaching programme. Final confirmation of project feasibility is expected in August 2006... [continues]


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Fisher , M.J. 1985. Palynology of sedimentary cycles in the Mercia Mudstone and Penarth Group (Triassic) of southwest and central England. Pollen et Spores, 27, 95-112.

Fisher, M.J. and Jean, C.V. 1982. Clay mineral stratigraphy in the Permo-Triassic red bed of BNOC 72/10-1A, Western Approaches and the South Devon Coast. Clay Minerals, vol. 17, pp. 79-89.
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Forster , A. 1998. The engineering geology of the Sidmouth district, 1:50000 geological sheet 326/340. British Geological Survey Technical Report, WN/98/1.

Jeans, C.V. 1978. The origin of the Triassic clay assemblages of Europe with special reference to the Keuper Marl [i.e. Mercia Mudstone] and Rhaetic [i.e. Penarth Group] of parts of England. Philosophical Transactions of the Royal Society of London, Series A, 289, pp. 551-636.


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Gallois , R.W. 2001. The lithostratigraphy of the Mercia Mudstone Group (mid to late Triassic) of the South Devon coast. Geoscience in south-west England, Proceedings of the Ussher Society, Vol. 10, 195-204. By Dr. Ramues Gallois.

Gallois, R W. 2001. Field excursion to examine the geology and landforms of the Charmouth to Lyme Regis area, 3rd January 2001. Geoscience in south-west England, Proceedings of the Ussher Society, Vol. 10, 243-246.

Gallois, R.W. 2003. The distribution of halite (rock salt) in the Mercia Mudstone Group (mid to late Triassic) in south-west England. Geoscience in south-west England, Proceedings of the Ussher Society, Vol. 10, 243-246.

Gallois, R.W. 2004. The type section of the junction of the Otter Sandstone Formation and the Mercia Mudstone Group at Pennington Point, Sidmouth. Geoscience in south-west England, vol. 11, pp. 51-58. (Pennington Point is east of Sidmouth).
An almost complete section through the Otter Sandstone Formation and the Mercia Mudstone Group is exposed in the cliffs between Budleigh Salterton and Axmouth on the south Devon coast. This is the most complete succession at this stratigraphical level in Britain and has been proposed as the type section for the formation and the group. The conformable junction of the Otter Sandstone Formation and the overlying Mercia Mudstone Group (Sidmouth Mudstone Formation) is wholly exposed in the cliffs at Pennington Point, Sidmouth over a distance of 250 m. The shingle beach that fronts this section of cliff is subject to seasonal variations in thickness of up to 5 m. The cliff and foreshore sections are continually refreshed by wave action at times of low beach level. They expose about 15 m of interbedded sandstone and mudstone, for which the new name Pennington Point Member of the Otter Sandstone Formation is proposed, overlain by the uniform mudstones of the Mercia Mudstone Group. The member marks the transition from the predominantly fluviatile environments of the Otter Sandstone Formation to the arid environments of the Mercia Mudstone Group. Concentrations of fossil material in winnowed deposits in the Pennington Point Member at Pennington Point have yielded a more diverse assemblage of vertebrate fossils than at any other Triassic locality in Devon. This includes genera previously known only from Russia and central Europe, and the type material for two new species. The section is nationally important for correlation at this stratigraphical level and internationally important for magnetostratigraphical comparison with sections in southern Europe. [end of abstract]

Gallois, R.W. 2004. The lithostratigraphy of the Upper Greensand (Albian, Cretaceous) of south-west England. Geoscience in south-west England, Proceedings of the Ussher Society, Vol. 11.

Gallois, R.W. 2004. Large-scale dissolution features in the Upper Greensand (Cretaceous) in south-west England. Geoscience in south-west England, Proceedings of the Ussher Society, Vol. 11.

Gallois, R.W. 2007. The stratigraphy of the Mercia Mudstone Group succession (mid to late Triassic) proved in the Wiscombe Park Boreholes, Devon. Geoscience in southwest England, 11, 280-286.
The type sections of the Sidmouth Mudstone, Dunscombe Mudstone and Branscombe Mudstone formations of the Mercia Mudstone Group are the almost complete sections exposed in the cliffs between Sidmouth and Axmouth on the Devon coast. The partially cored Wiscombe Park No. 1 and No. 2 mineral-exploration boreholes, drilled by British Gypsum Ltd in 1972, were sited about 5.8 and 4.7 km north of the cliff sections respectively. The first of these penetrated the whole of the Sidmouth MudstOne and Dunscombe Mudstone formations and the lower part of the Branscombe Mudstone Formation. The lithological succession proved in the cored parts of the bore holes can be correlated with that exposed in the cliffs. Geophysical logs made through the full length of the boreholes enable the complete succession proved there to be correlated with that exposed in the cliffs. The calibrated geophysical logs have been used to correlate the succession at outcrop with those proved in uncored but geophysically logged hydrocarbon-exploration boreholes throughout the Wessex Basin. The Sidmouth Mudstone and Branscombe Mudstone successions proved in the Wiscombe Park boreholes are similar in thickness and lithology to those elsewhere in the Wessex Basin. In contrast, the Dunscombe Mudstone succession in the boreholes expands from 35 m in thickness to over 500 m by the addition of thick beds of halite in parts of the basin.

Gallois, R.W. 2007. A recent landslide on the east Devon coast, U.K. Quarterly Journal of Engineering and Hydrogeology, vol. 40, pp. 29-34.
Extract from p.2 : "Salcombe Regis Landslide, 2006. The landslide occurred in the early hours of January 4th 2006 at the western end of Higher Dunscombe Cliff, Salcombe Regis [east of Sidmouth], adjacent to the 2001 toppling failure. No person or property was involved, but a section of about 150m of the Southwest Coastal Path and an adjacent hedge and fence fell about 160 m to the beach. The width of the collapsed mass varied at cliff-top level from about 5 to 20 m. It is estimated that the total mass of the landslide was about 250,000 tonnes. The debris spread out to a 200 plus m width of the beach and intertidal area. Individual blocks of up 5 x 5 x 4 m of the more durable lithologies came to rest up to 150 m beyond the foot of the cliff, below the low-water level of Spring tides. ...."
continues with several colour photographs and colour diagrams, and with eight references. 8 pages in total.

Gallois, R.W. 2013. The relationship of stratigraphically controlled lithological variations in the Mercia Mudstone Group (Triassic) in South-West England to weathering processes and landslide mechanisms. Geoscience in South-West England, 13, pp. 172-182.
The principal exposures of the 350 m to 450 m thick Mercia Mudstone Group in South-West England are cliff sections on the east Devon coast between Sidmouth and Seaton, and on the north Somerset coast between Blue Anchor and St Audrie’s Bay. Inland, where the mudstones weather to clays that form slopes that mostly rest at 5º to 10º, there are few exposures. The group is divided on gross lithology into four formations and nine members, each of which influences the shapes of the cliff profiles and the types of landside mechanism. On the Devon coast, failures in the lower part of the cliffs in the red silty mudstones of the Sidmouth Mudstone and Branscombe Mudstone Formations are initiated by marine erosion acting on joints and bedding planes: in the middle part by joint-bounded rock-block failures; and in the upper part by toppling failures and the failure of weak mudstone soils in the weathered zone. Thin (less than 10 mm thick) beds of laminated grey mudstone in the Dunscombe Mudstone and Blue Anchor Formations give rise to rotational and translational shear failures on the Devon coast. On the Somerset coast, where there is a large (up to 12 m) tide range and the cliffs are less protected by beach deposits, the principal landslide mechanisms are rock-block and toppling failures that are strongly influenced by faulting and have little relationship to the stratigraphy. Landslides in the Mercia Mudstone Group are rare in inland Devon and Somerset except for shallow-seated failures close to the spring line and unconformity at the base of the Cretaceous Upper Greensand Formation, and in some of the narrow, steep-sided valleys (goyles) on the Upper Greensand outcrop in East Devon.

Gallois, R.W. and Porter, R.J. 2006. The stratigraphy and sedimentology of the Dunscombe Mudstone Formation (late Triassic) of south-west England. Geoscience in South-West England, 11, 67.

Gallois, R.W., Pirrie, D., Power, M.R. and Shail, R.K. 2004. Copper mineralised wood from the Mercia Mudstone Group, south-east Devon. Geoscience in South-West England, 11, 67.


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Godwin-Austen , R.A.C. 1840. On the geology of the south-east of Devonshire. Transactions of the Geological Society, London, series 2, vol. 6, pp.433-489.
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Hamblin , R.J.0., Crosby, A., Balson, P.S., Jones, S. M., Chadwick, R.A., Penn, I.E., and Arthur, M.J. 1992. United Kingdom Offshore Regional Report: the Geology of the English Channel. British Geological Survey, H.M.S.O., London.
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Henson , M.R. 1971. The Permo-Triassic Rocks of South Devon. Unpublished Ph.D. Thesis, University of Exeter.

Henson, M.R. 1972. The form of the Permo-Triassic basin south east Devon. Proceedings of the Ussher Society, 2, 447-457.

Henson, M.R. 1973. Clay minerals of the Lower New Red Sandstone of south Devon. Proceedings of the Geologists' Association, 84, 429-445.
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Holloway, S., Milodowski, A.E., Strong, G.E. and Warrington, G. 1989. The Sherwood Sandstone Group (Triassic) of the Wessex Basin, southern England. Proceedings of the Geologists' Association, London, 100 (3), 383-94. Data from released wells indicate that the subdivision of the Sherwood Sandstone Group into the Budleigh Salterton Pebble Beds and the Otter Sandstone Formation is equally applicable in both the outcrop and subcrop of the Group in the Wessex Basin. The Sherwood Sandstone Group was deposited largely from braided streams but an inland sabkha may have occupied the depocentre during deposition of the lower parts of the Otter Sandstone Formation. The Budleigh Salterton Pebble Beds may have been removed from parts of the Wessex Basin by erosion prior to deposition of the Otter Sandstone Formation.


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Hone , D.W.E. and Benton, M.J. 2008. A new genus of rhynchosaur from the middle Triassic of south-west England. Palaeontology, vol. 51, Issue 1, pp. 95-115. By David W. E. Hone and Michael J. Benton, Department of Earth Sciences, University of Bristol, Bristol BS8 1RJ, UK. and Bayerische Staatssammlung fur Palaontologie und Geologie, Richard-Wagner-Strasse 10, D-80333 Munchen, Germany. The Palaeontological Association.
Abstract: We present a description of new cranial and postcranial material representing a new genus of rhynchosaur (Diapsida, Archosauromorpha) from the Otter Sandstone Formation (Mid Triassic) of Devon, south-west England. The taxon had been named Rhynchosaurus spenceri Benton, 1990, but cladistic analysis of the clade, and one autapomorphy, show that it does not belong to Rhynchosaurus, and a new generic name is required. We propose the name Fodonyx for this genus. A cladistic analysis of the Rhynchosauria confirms the main discoveries of previous analyses, and that Fodonyx is sister group to the Hyperodapedontinae, the clade of Late Triassic rhynchosaurs. The new cladistic analysis, for which many more characters were coded for Fodonyx than before (a rise from 39 to 75 per cent), counter-intuitively produced less well-resolved results: the new codings of previously uncoded characters introduced conflict so that Fodonyx turns out to be less like the Late Triassic rhynchosaur clade than had been assumed before.
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Hounslow, M.W. McIntosh, G., Edwards, R.A. and Warrington, G. The magnetostratigraphy of the Permo-Triassic of south Devon. .....
The Budleigh Salterton Pebble Beds and the Otter Sandstone Formation of the Sherwood Sandstone Group were sampled for magnetostratigraphy at 94 horizons between Budleigh Salterton and Sidmouth. The palaeomagnetic signal is predominantly carried by haematite, with some additional signal from goethite. The Budleigh Salterton Pebble Beds are entirely reversely magnetised. The Otter Sandstone has a complex pattern of polarity changes. The lowest beds, west of the River Otter, have predominantly normal polarity. The lower c.100m of the formation exposed east of the River Otter is predominantly reversely magnetised but has two short normal polarity intervals; the upper c.70m of the formation has dominantly normal polarity but includes six reversed intervals. The lowest 15m of the Mercia Mudstone Group was also studied and displays normal polarity, except at the very base. Combined bio- and magnetostratigraphic evidence indicates that the Otter Sandstone Formation is Mid Triassic in age, ranging from early Anisian in the lowest beds to late Anisian to possibly early or mid Ladinian in the upper c.70m. The Sherwood Sandstone Group-Mercia Mudstone Group boundary therefore probably lies within the Ladinian Stage (upper Middle Triassic). The Budleigh Salterton Pebble Beds may, on the basis of these results and bio- and magnetostratigraphic evidence from the underlying Aylesbeare Group and older formations, lie within the Olenekian Stage and are possibly latest Early Triassic in age.

Hounslow, M.W., McIntosh, G. and Jenkins, G. 2001. Magnetostratigraphy of the Middle Triassic: Sherwood Sandstone Group, South Devon, UK, EGS Nice.

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Howard, A. S., Warrington, G., Ambrose, K. and Rees, J. G. 2008. A formational framework for the Mercia Mudstone Group (Triassic) of England and Wales. British Geological Survey, Natural Environment Research Council. A National Geoscience Framework Programme. British Geological Survey Research Report: RR/08/04. Available online as a pdf file of 33 pp., including diagrams etc.
File name: Mercia_Mudstone_150408%65B1%5D.pdf
See Fig. 5 on p. 27. regarding Sidmouth. This is a key diagram with sosme revision regard to terminology of lithostratigraphy of the South Devon/ Dorset area. The sequence in this region is now listed as follows:
Lias Group [i.e. Lower Lias etc at Lyme Regis]
Penarth Group [formerly the "Rhaetic" at Pinhay Bay]
Branscombe Mudstone Formation [upper part of the Mercia Mudstone Group]
Arden Sandstone Formation [known at Sidmouth as the Dunscombe Mudstone Formation.]
Sidmouth Mudstone Formation [lower part of the Mercia Mudstone Group]
Otter Sandstone Formation [upper part of the Sherwood Sandstone Group]
Budleigh Salterton Pebble Beds Formation [lower part of the Sherwood Sandstone Group]

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Hunt, A.R., 1880, 1881, 1883, 1885. On the submarine geology of the English Channel off the coast of south Devon. Transactions of the Devon Association.
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Hutchinson, P.O. The Geology of Sidmouth and South-Eastern Devon. Sidmouth.
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Irving , A. 1888. The Red-Rock Series of the Devon coast section. Quarterly Journal of the Geological Society of London, vol. 44, pp. 149-163. By the Rev. Dr. A. Irving.
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Jarvis, I., and Woodroof, P. B. 1984. Stratigraphy of the Cenomanian and basal Turonian (Upper Cretaceous) between Branscombe and Seaton, SE Devon, England. Proceedings of the Geologists' Association, Vol. 95, 193-215.
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Jeans , C.V. 1978. The origin of the Triassic clay assemblages of Europe with special reference to the Keuper Marl and Rhaetic of parts of England. Philosophical Transactions of the Royal Society of London, Series A, 289, 549-639.
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Johnston-Lavis , H.J. 1876. On the Triassic strata which are exposed in the cliff-sections near Sidmouth, and a note on the occurrence of an ossiferous zone containing the bones of a Labyrinthodon. Quarterly Journal of the Geological Society of London, vol. 32, pp. 274-277.

[text follows, but without the cliff diagram]
In describing the locality and geological position of the vertebrate fossils which were obtained from the Triassic rocks near Sidmouth, perhaps it would be as well to commence with a description of the coast-sections for a short distance east and west of that town. Starting from the east, we find that the Marl [Mercia Mudstone = Keuper Marl] (which is the uppermost subdivision of the Trias of South Devon) makes its appearance at Branscomb Mouth, exposed beneath the Greensand and Chalk in the cliff-sections, and in the ramifying valley cut through by the small stream which runs out to sea at this point. It now forms the lower portion of the, cliff under Littlecomb Hill and Branscomb Hill, being overlain by the Greensand and Chalk until it is exposed inland at Weston Mouth by the action of the little stream called Weston Water, which runs out here.
It again forms the base of the cliff under Dunscomb Hill, being still overlain by the Greensand and a small patch of Chalk; again it is exposed and partly excavated by the little brook at Salcomb Mouth; thence it forms the base of the cliff under Salcomb Hill [Salcombe Hill], being now capped by the Greensand alone; it is then largely exposed on the surface in the valley of the river Sid. A few yards east of where the Sid runs into the sea, the Upper Sandstone (of Mr. Ussher) crops out, forming a cliff overhanging the Sid, and constituting the bed of the stream for half a mile from its mouth, and also the whole valley except where covered by gravel, which Mr. Ussher tells me is in some places 15 feet thick, containing a bed of peat about a foot in thickness. The gravel is chiefly composed of chert, and contains teeth of Elephant [Mammoth], numerous specimens of which have been found by Mr. P. O. Hutchinson and others.
To the west of Sidmouth, at the end of the Parade, we meet with a low projecting cliff, called Chit Rock. Mr. Ussher, who has surveyed this district, tells me he has met with no evidence of a fault having existed in the valley; and therefore we may conclude that it is the continuation of the small exposure of sandstone which is seen to exist east of the river, as in section, fig. 1 (p. 276). At the western end of the Chit Rock we find a fault which has given the Chit Rock an upthrow of at least 40 feet; but it is very possible it may be as much as 80 feet, since it has no marl [Mercia Mudstone = Keuper Marl] capping it, and in its lithological character resembles the middle of the Upper Sandstone [Otter Sandstone]. We see, on the western side of the fault, the Marl brought down within a short distance of the beach, there being a small mass of Sandstone exposed beneath it. All the Triassic beds from Branscomb [Branscombe] up to the present place dip gently to the east; but now we :find them dipping to the west; this only takes place for the distance of about half a mile; for the Sandstone which had disappeared, soon makes its appearance again, having formed a synclinal curve. During the whole of this distance it has been covered by the marl, which, as it advances westward becomes thicker, being less denuded; it has cappings of Greensand and chalk-gravel [Clay with Flints] at Peake Hill [Peak Hill] and High Peake [High Peak]. The [Otter] Sandstone continues to rise gradually to the westward; but the Marl [Mercia Mudtone] and overlying Greensand have been cut down by atmospheric denudation, forming Windy Gap, which separates High Peake and Peake Hill - High Peake being the higher of the two, but resembling Peake in every other respect. The [Otter] Sandstone gradually rises until, at a short distance to the west of High Peake, the Marl has been entirely denuded (save in a few places where through faulting it has been brought to a lower level) and it appears on the surface.
The upper marls [Mercia Mudstone] are variegated, and especially in the higher part, east of Sidmouth, contain very thin layers of a greenish-grey sand mixed with a large quantity of mica, intercalated with layers of marl, varying in thickness up to two inches, but of the same light colour; they show ripple-marks, and occasionally contain pseudomorphs of rock-salt.
The marls between Weston and Branscomb Mouths contain a large quantity of gypsum, which at one time was worked at Branscomb Mouth. A few small veins are to be seen between Salcomb and Weston Mouths. The marls also contain bands of potato-stones enclosing a cavity lined with calcite [these geodes result from partial calcitisation of former gypsum or anhydrite nodules of sabkha origin]. Mr. H. B. Woodward objects to my giving them the name of potato-stones, as they do not contain quartz crystals [they are of similar origin to the Triassic potato-stones of Somerset].
The Sandstone, especially at its upper part, where it resembles very much in lithological characters the upper beds of marl, contains a large number of pseudomorphs of rock salt, ripple-marks, and sun-cracks; but in no case have I met with rain-marks, which we might expect; neither have I met with any foot-prints. Some of the upper sandstones effervesce with hydrochloric acid. Between High Peake and Otterton Point the sandstones contain spherical masses sometimes almost like a cannon-ball, composed of iron pyrites; these are washed out of their matrix and lodge at the bottom of the little rocky pools.
The sandstones also contain curious irregular branching-shaped masses of a harder texture, which withstand the weathering and give the cliff a rugged aspect [these are rhizoconcretions - root concretions]. It is worthy of notice that, at the points where the Marl [Mercia Mudstone] reaches down to the beach, there are no reefs on the foreshore opposite, but a beautiful fine-grained red sand, except where large blocks of chert have fallen from the Greensand capping the cliffs; but wherever the Sandstone appears above the beach one sees large reefs running out to sea for nearly half a mile at low tide; it does not seem to be the sandstone itself which withstands the weathering, but these curious hard masses contained in it, since they occur in all the projecting points of the cliff formed by the sandstone strata.
Last autumn, while on a visit to Sidmouth for the second time, I had the good fortune to find the bones of a Labyrinthodont. These were brought to light at different periods during my month's stay. It may be mentioned that those described by Prof. Seeley are merely the bones which I considered capable of identification; for I met with a great number of small fragments dispersed throughout a particular series of beds situated about 10 feet from the top of the Sandstone. These bones were mostly found in fallen blocks which were derived from these beds in a little cove known as Picket Rock Cove [between Picket Rock, near Ladram Bay and High Peak]. It may be well termed an ossiferous zone, as it does not consist of one single bed, but of from one to four; not that I mean to imply that bones are only found in this zone, since Mr. Whitaker's Hyperodapedon [Hyperodapedon is a genus of rhynchosaur, a beaked, archosaur-like reptile. It is known from the Trias of Elgin, Scotland, the Trias of the Parana Basin, Brazil, the Trias of India etc.] from the Triassic Period was found at the very bottom of the Sandstone. This zone is characterized by lithological differences, inasmuch as the matrix is composed of much coarser sandstone, containing here and there masses of marl varying in size from that of a pea to that of a hen's egg. It is nearly hard enough in some places for building purposes. In these beds ripple-marks are very plentiful. The fragments of bone which are found in this zone seem to be very slightly waterworn.
I cannot conclude without expressing my thanks to Messrs. H. B. Woodward, W. A. E. Ussher, and W. Whitaker for the kind assistance they have afforded me, and to Mr. P. O. Hutchinson, of Sidmouth, for the artistic diagrams with which he has furnished me. P.S.- Since writing the above I have received from the Rev. S. H. Cook some fragments of bone obtained by him about twenty years ago from the same zone west of Sidmouth, as well as one which he recently obtained from the small outcrop of sandstone with the ossiferous zone on the western side of the Chit-rock fault. Below the ordinary red sand on the beach one finds a stratum of black sand which has been derived from the sandstone, but is of greater specific gravity than the red sand, which accounts for its position on the beach. Mr. R. W. Cheadle has kindly made a qualitative analysis for me, with the following rough results-Silica, magnetic iron oxide [magnetite], manganese, titanium, and alumina [is this a magnetite-ilmenite "black sand"?].
[not included here - Fig. Bird's Eye View of the Cliff-section from Ladram Bay to Sidmouth. This shows, amongst other features, the distribution of the "Ossiferous Zone".]
[The paper is followed by that of H.G. Seeley (1876) on the Lower Jaw of a Labyrinthodont (discussed above). Quarterly Journal of the Geological Society]


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Jones , N.S. 1992. Sedimentology of the Permo-Triassic of the Exeter area, S.W. England. British Geological Survey Technical Report, WH/92/122R.

Jones, N.S. 1993. Sedimentology of selected Triassic and Cretaceous successions from the Sidmouth area, Devon. British Geological Survey, Technical Report, WH/93/61R.
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Jukes-Browne , A.J., and Hill, W. 1900. The Cretaceous rocks of Britain. Vol. 1. The Gault and Upper Greensand of England. Memoir of the Geological Survey of the United Kingdom, London: HMSO.
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Knox , R.W.O., Burgess, W.G., Wilson, K.S. and Bath, A.H. 1984. Diagenetic influences on reservoir properties of the Sherwood Sandstone (Triassic) in the Marchwood geothermal borehole. Clay Minerals, 19, 441-456.
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Krinsley , P. H., Friend, P. F., and Klimentidis, R. 1976 Eolian transport textures on the surfaces of sand grains of early Triassic age. Bulletin of the Geological Society of America, 87, 130--132.
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Laming, D. J. C. 1958. Fossil winds. In Polar wandering and continental drift - a symposium, Journal of the Alberta Society of Petroleum Geologists, 6, Calgary, 179-183.

Laming, D. J. C. 1965. Age of the New Red Sandstone in south Devonshire. Nature, London, 207, 624-625.

Laming, D. J. C. 1966. Imbrications, palaeocurrents and other sedimentary features in the Lower New Red Sandstone, Devonshire, England. Journal of Sedimentary Petrology, 36, 940-959.

Lott, G.K., Sobey, R.A., Warrington, G. and Whittaker, A. 1982. The Mercia Mudstone Group in the western Wessex Basin. Proceedings of the Ussher Society, vol. 5, pp. 25-53.


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McKie , T., Aggett, J. and Hogg, A.J.C. 1998. Reservoir architecture of the upper Sherwood Sandstone, Wytch Farm field, southern England. In: Underhill, J.R. (Ed.) Development Evolution and Petroleum geology of the Wessex Basin. Geological Society Special Publication, 133, 399-406.
The Sherwood Sandstone Group reservoir in the Wytch Farm field comprises a c. 150 m thick succession of arkosic sandstones deposited in a variety of fluvial, lacustrine and aeolian depositional systems. These systems show at least three orders of facies variability, which are interpreted to be the depositional response to climatic changes. These comprise a first-order evolutionary trend over the entire Sherwood Sandstone Group from perennial braidplain to ephemeral sheetflood systems to ephemeral lacustrine conditions. This trend culminated in deposition of the Mercia Mudstone Group, and reflects a long-term waning of sand supply and increasing 'flashiness' of the fluvial system. This trend is further subdivided into second-order cycles defined by five areally widespread floodplain and lacustrine deposits containing minimal development of fluvial sandstones. These represent widespread, episodic reductions in fluvial sediment supply and rising base level during more 'humid' climatic conditions. These horizons form the basis for the reservoir layering scheme. Each floodplain episode is increasingly more mud-rich upwards through the Sherwood section, and the sand-rich fluvial packages between become systematically more ephemeral in character. Third-order cycles are defined by thin (less than 2 m), but already widespread floodplain and lacustrine horizons which are most readily identifiable in the upper half of the Sherwood section. The sandstones between these cycles are composed of aeolian and sheetflood deposits, but are incised by coarse-grained multistorey-multilateral channel deposits. The incisions are interpreted to be the result of fluvial erosion during dry climatic conditions when lake levels fell and the alluvial plain was devegetated. These incised fluvial deposits form the principal producing intervals in the upper part of the reservoir, particularly in the eastern part of the field. Higher frequency stratigraphic cycles are locally expressed by variations in ephemeral lake levels, palaeosol development and episodic development of wind-blown sand patches. At outcrop, the stratigraphically equivalent Otter Sandstone Formation (c. 100 km to the west) shows comparable evolutionary patterns, albeit with a subtly different facies make-up. The recognition of a hierarchy of climatically driven cycles within the reservoir permits high-resolution correlation and the recognition of subtle, but important, changes in sandbody geometry and connectivity within successive cycles.
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Metcalfe, -- On further discoveries of vertebrate remains in the Triassic strata of the south coast of Devonshire, between Budleigh Salterton and Sidmouth. Quarterly Journal of the Geological Society of London, vol. 40, pp. 257-262.


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Milodowski , A.E., Strong, G.E., Wilson, K.W., Allen, D.J. Holloway, S. and Bath, A.H. 1986. Diagenetic influences on the aquifer properties of the Sherwood Sandstone in the Wessex Basin. Investigation of the geothermal potential of the UK. British Geological Survey, Keyworth.


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Morton, A., Hounslow, M.W. and Frei, D. 2013. Heavy-mineral, mineral-chemical and zircon-age constraints on the provenance of Triassic sandstones from the Devon coast, southern Britain. Geologos, vol. 19, (2013), pp. 67-85. By Andrew Morton, Mark W. Hounslow and Dirk Frei. Available free online.
An integrated heavy-mineral, mineral-chemical and zircon-dating study of the Triassic succession exposed on the south Devon coast, in the western part of the Wessex Basin, indicates derivation from a combination of granitic and metasedimentary lithologies of ages of mostly over 550 Ma. These sources were probably located at a relatively proximal location near the southern margin of the basin. Derivation from more distal sources in the Armorican Massif or local Variscan sources to the west appears unlikely in view of the scarcity of Permo-Carboniferous (Variscan-age) zircons. The Budleigh Salterton Pebble Bed Formation was derived from a different combination of source lithologies than the Otter Sandstone Formation, the former including staurolite-grade metasediments that were absent in the catchment area of the Otter Sandstone. The Devon coast succession has provenance characteristics that differ from equivalent sandstones further east in the Wessex Basin, and from sandstones in the East Irish Sea Basin to the north. These differences indicate that sediment supply patterns to the linked Triassic basin systems in southern Britain are complex, involving multiple distinct sub-catchment areas, and that heavy-mineral studies have considerable potential for unravelling these sub-catchment area sources.

Morton, A., Knox, R. and Frei, D. 2016. Heavy mineral and zircon age constraints on provenance of the Sherwood Sandstone Group (Triassic) in the eastern Wessex Basin. Proceedings of the Geologists' Association, vol. 127, pp. 514-516. By Andrew Morton, Robert Knox and Dirk Frei.
Abstract: Heavy mineral and zircon age data demonstrate that in the Sherwood Sandstone Group of the Marchwood-1 and Southampton-1 boreholes on the eastern margin of the Wessex Basin, sediment was supplied from both the south (Variscan Highlands) and the east (recycled Old Red Sandstone). Interplay of these two sources led to a well-defined heavy mineral stratigraphy in the area. However, the Sherwood Sandstone Group in the Wytch Farm oilfield in the centre of the Wessex Basin, contains only sandstones derived from the Wessex highlands to the south and lacks significant amounts of recycles Old Red Sandstone detritus. The equivalent sandstones (Otter Sandstone Formation) on the western margin of the Wessex Basin have a different provenance to both the central and eastern parts of the basin, since they lack input from Variscan granitoids. Heavy mineral and zircon provenance data therefore demonstrate sediment input from a number of discrete source areas into the Wessex Basin during the Early and Middle Triassic, and that the "Budleighensis River" system may not have been a single river, at least in the southern Wessex Basin area. It is also evident that provenance-based correlation schemes such as heavy mineral analysis or whole rock geochemistry should be used with caution over long distances and require careful evaluation of lateral changes in provenance. [Keywords: Provenance, Correlation, Trias, Triassic, Wessex Basin, Zircon, Budleigh Salterton, Sherwood Sandstone, Wytch Farm Oilfield, Southampton].


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Newell, A. J. 2001. Bounding surfaces in a mixed aeolian-fluvial system. Marine and Petroleum Geology, vol. 18, no. 3, pp. 339-347.
The Dawlish Sandstone Formation is a Late Permian succession of mixed aeolian and fluvial deposits in the Wessex Basin (SW England). It is used to illustrate two contrasting types of fluvial/aeolian bounding surface (planar and incised). Planar bounding surfaces separate tabular bodies of fluvial conglomerate and aeolian dune sandstone. They were produced primarily by wind scour to groundwater table, with the later emplacement of conglomerates resulting in local fluvial erosion of cemented aeolian dune sandstones. Incised bounding surfaces were produced by fluvial downcutting. The erosive relief was infilled with mixed aeolian/fluvial deposits. The Dawlish Sandstone Formation may provide the first outcrop example of these incised valley fills, which have recently been identified as a major component of the subsurface Rotliegend in the Southern North Sea Basin. The potential variability of aeolian/fluvial sedimentary architecture has important implications for well-to-well correlation and reservoir modelling.
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Parthasarathi Ghosh, Soumen Sarkara and Pradip Maulika, 2006. Sedimentology of a muddy alluvial deposit: Triassic Denwa Formation, India. Sedimentary Geology, 191, Issues 1-2, pp. 3-36. Available online in full at Science Direct.
Abstract: Triassic Upper Denwa Formation (380 m) in the Satpura Gondwana basin, central India is a mudstone-dominated fluvial succession that comprises isolated ribbon-shaped (2-5 m thick) channel-fill bodies encased within fine-grained extra-channel deposits. Eight architectural elements are recognized, of which five belong to channel-fill deposits and the remaining three to extra-channel deposits. Majority of channel-fill deposits are characterized by sandy or muddy inclined heterolithic strata (IHS) that record limited lateral accretion of point bars or benches (constrained by cohesive banks) in mixed- to suspended-load sinuous channels. A few ribbon bodies are mud rich and attest to nearly stagnant conditions in partly abandoned channels. A few single- or multistorey ribbon bodies that are dominantly sandy and lack inclined strata represent deposits of straight, laterally stable channel. The smallest ribbon bodies (1 m thick) of calcirudite/calcarenite possibly represent deposits of secondary channels in the interfluves. Coexistence of channel-fill bodies of different dimension, lithology and internal organization in restricted stratigraphic intervals suggests an anabranching system having channels with different fill histories.
The extra-channel deposits mainly comprise red mudstone (1-5 m thick) that indicates pervasive oxidation of overbank sediments in well-aerated and well-drained setting. Sporadically developed calcic vertisols suggest a hot, semi-arid climate during the Upper Denwa period. Sandy to heterolithic sheets (70 cm to 2 m thick) with sharp, planar basal surfaces are replete with features suggestive of unconfined sheet flow. Also at places there are indications of subaqueous emplacement of sands. These bodies with paleocurrent oblique to that of the channel-fills are interpreted as crevasse splay deposits. Tabular heterolithic bodies (3-5 m thick) are characterized by undulating basal surface, complex organization of sandstone lenses interwoven with heteroliths and red mudstone (in decimeter-scale) with desiccation cracks. Such tabular bodies are attributed to repetitive, sheet-like and poorly channelized splaying.
Very thick (10 to 20 m) mudstones intervals are inexplicable in terms of overbank flooding only. Poorly developed pedogenic features in sandy to muddy heterolithic sheets and certain mudstone intervals and well-developed cumulative paleosols in surrounding mudstone highlights the contrast between rapidly emplaced splay deposits and slowly accumulated floodplain deposits.
The Denwa channels are comparable with modern, low-gradient and low-energy anabranching river system in which the sediment load is dominantly fine-grained. The semi-arid climate possibly facilitated enhanced supply of fines to the Upper Denwa system. However, sediment partitioning and distribution in a particular channel was controlled by flow diversion to and from other channels in that anabranching system. Low flow strength with periodic flood events, high bank strength and a rate of sediment supply that slightly exceeded that of onward transport probably were important factors for the development of the Upper Denwa anabranching system.
[end of abstract] [This interesting paper does not refer to Devon, but deals with a Triassic semi-arid red bed facies in India. It includes channels sandstones, inclined heterolithic facies, and red mudstones (some of which have green reduction spots). It describes and interprets architectural elements, and because of this may be of use in comparison to Triassic red beds of Devon. Bear in mind, though, that it is from a higher palaeolatitude 930 to 40 degrees) and south of the equator, not north. The paper is also useful as a route to recent Triassic red bed literature.]
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Pengelly , W. 1862-65. The Red Sandstones and Conglomerates of Devonshire. Transactions of the Plymouth Institute.
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Perkins , J.W. 1971. Geology Explained in South and East Devon. David and Charles, Newton Abbot, 192pp. By John W. Perkins. Clearly written with very good, well-labelled, sketch illustrations by the author.
Extract from the Introduction:
"The basic ingredients of the county's rolling landscape are the high moorland centre, the surrounding low lands bevelled to various heights and deeply trenched by rivers, and the sinuous coastline with its penetrating estuaries and grand cliffs. Written for all who love South Devon, either as a tourist area or a place to live in, this book aims to deepen their understanding and enjoyment. It may also help to popularise geology in a wider sense, and should remind us that we are tenants of a heritage millions of years old, and one that we must do our best to conserve. It has been assumed throughout that the reader will constantly have a compass, a one-inch geological map and a one inch Ordnance Survey map at hand."
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Porter , R. J. 2006. Ichnology and sedimentology of Triassic continental sequences: onshore and offshore UK. Unpublished Ph.D. thesis, University of Bristol, U.K.

Porter, R.J. and Gallois, R.W. In press. Identifying fluvio-lacustrine intervals in thick playa-lake successions: an integrated sedimentology and ichnology of arenaceous members in the mid-late Triassic Mercia Mudstone Group of southwest England, UK. Palaeogeography, Palaeoclimatology and Palaeoecology.


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Romer , A.S. 1945 (second edition), 1955 (reprinted). Vertebrate Paleontology. The University of Chicago Press, Chicago, Illinois, 687pp.


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Ruffell , A. 1991. Palaeoenvironmental analysis of the the late Triassic succession of the Wessex Basin and correlation with surrounding areas. Proceedings of the Ussher Society, 7, 402-407.

Ruffell, A. and Shelton, R. 1999. The control of sedimentary facies by climate during phases of crustal extension: examples from the Triassic of onshore and offshore England and Northern Ireland. Journal of the Geological Society, London, 156, 779-789. Abstract: Crustal extension controls the tectonic accommodation space available for sediments in rift settings and may be defined by the structural and depositional geometry of sedimentary successions observed on seismic data and the rate of subsidence through time as represented by the accommodation of sediment. The characteristic features of each are dependant on three variables: the time taken for deposition; the interplay between tectonics and eustasy and the lithology (thus facies) of the succession observed. The Sherwood Sandstone Group has been considered to represent a syn-rift phase of fluvial deposition throughout Europe, with the overlying Mercia Mudstone Group interpreted as the succeeding phase of deposition in an evaporitic seaway during post-rift thermal subsidence. More recently, however, there has been the recognition that it is the Mercia Mudstone Group which is seen to thicken markedly into faults imaged on seismic data rather than the Sherwood Sandstone Group. This work demonstrates the Mercia Mudstone Group to be a syn-rift phase of deposition, with the fine grained nature of the sedimentary record at this time controlled by the prevailing arid climate. Such conditions were not conducive to the large-scale and rapid movement of sediments from the hinterlands raised by relative footwall uplift, thus the sediments are fine grained. The minor thickening of the Sherwood Sandstone Group into faults is interpreted to be a combination of minor extension in the early Triassic superimposed on thermal subsidence inherited from the important regional phase of extension in the early Permian. Analysis of the timing of fault growth indicates a larger proportion of fault-controlled, synsedimentary movement occurred during the mid-to-Late Triassic (Mercia Mudstone Group) rather than the early Triassic (Sherwood Sst Gp).


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Schmid, S., Worden, R. and Fisher, Q. 2003. The time has changed: middle Triassic climate changes revealed by carbon isotopes. Geophysical Research Abstracts, vol. 5, 00325. European Geophysical Society. Abstract: The Middle Triassic stratigraphy in Europe can be subdivided into a marine sectionof the Germanic and Paris Basin and a continental red-bed succession of Western Europe (Irish Basin, Wessex Basin). The link between the marine and continental is uncertain due to a lack of biostratigraphic information but recent palaeomagnetic studies have given a better understanding of the two environments (Hounslow et. al, 2001). In this study we have produced geochemical evidence which emphasize the implications of the palaeomagnetic data. We show that the marine and continental strata can be correlated using carbon isotopes. Throughout Europe the Middle Triassic is characterized by limestone deposits of the Muschelkalk Formation that contain evidence of a hiatus in sedimentation due to sea-level fall in the Middle Muschelkalk with the consequent deposition of evaporites. The Sherwood Sandstone Group (SSG) characterizes the Middle Triassic of Western Europe. The SSG is dominated by fluvial deposits with intercalated floodplain deposits, sand-flats and playas, which are penetrated by dolocretes and calcretes. The abundance of fluvial channels and sand flats are dependent on the fluvial activity and the water table height. In both depositional environments water plays a major role in the type of sediment. The volume of water is controlled by the prevalent climate. Climate signals are stored in carbon isotopes in both the marine Muschelkalk and the continental SSG. Carbon isotopes from the SSG from the Corrib Field, Slyne Basin, west of Ireland and from the Muschelkalk of the Germanic Basin have thus been interpreted in terms of climate change linked to stratigraphy. The continental sediments show a distinct positive carbon isotope excursion (taken from dolocretes),which is interpreted to present a more arid climate. In contrast the marine limestones exhibit a negative carbon isotopes excursion from a sea level low stand for the same time interval. The plot of both carbon isotopes curves against depth (using the Anisian-Ladinian boundary as a correlation marker) with a correction of sediment thickness show the same general climatic conditions for the Middle Triassic in Europe. Carbon isotope data from the Muschelkalk of the Germanic Basin and the SSG of the Slyne Basin reveal that the Middle Triassic was a time that witnessed a change from a humid to an arid climate with less fluvial activity in the continental parts and evaporite deposition in the marine part of Europe.
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Sidmouth Museum. 2000. Sidmouth: A History. 115pp. First edition: 1987, reprinted 1988, revised edition 2000.


Simms, M.J. 2003. Uniquely extensive seismite from the latest Triassic of the United Kingdom: Evidence for bolide impact? Geology. v. 31 no. 6 p. 557-560. By By Michael J. Simms.
Abstract:
A 2-4 m thick seismite, in places overlain by a previously unreported tsunamite, can be traced across greater than 250,000 km2 of the outcrop and subcrop of the latest Triassic (Rhaetian) Cotham Member of the Penarth Group, United Kingdom, an extent unique for the British Phanerozoic. Its consistent thickness, intensity of deformation, and preferred orientations of slump-fold axes indicate a seismic event of M greater than 10 with an epicenter greater than 600 km W or NW of central Britain. The magnitude of the event is incompatible with known terrestrial mechanisms (fault, volcano) but is consistent with a major bolide impact. A short, but unknown, interval separates the top of the Cotham Member seismite from major geochemical and biotic perturbations associated with the end-Triassic extinction, although a direct link between the seismite and these other events remains equivocal. The exceptional extent of "mega-seismites" such as this may prove a useful indicator of previously undocumented bolide impacts.


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Somervail , A. 1903. On the base of the Keuper in south Devon. Geological Magazine, pp. 460-462; also Geological Magazine, 1904, p. 283; also Reports of the British Association for the Advancement of Science for 1903.

Somervail, A. 1903. The Red Rocks of the South Devon Coast. Transactions of the Devon Association, vol. 35, ppp. 617-630.


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Spencer , P.S. and Isaac, K.P. 1983. Triassic vertebrates from the Otter Sandstone Formation of Devon, England. Proceedings of the Geologists' Association, London, Vol. 94, 267-269.


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Thomas, H.H. 1909. A contribution to the Petrography of the New Red Sandstone in the West of England. Quarterly Journal of the Geological Society, London, vol. 65, pp. 229-245. By Herbert Henry Thomas, M.A., B.Sc., F.G.S. (Read March 10th, 1909).
The following example text from p.242 brings out the major conclusions, including the interesting aspect of a distant source of staurolite:

From a study of the distribution and quantity of certain mineral species, it is possible in most instances to gather some idea of the relative amounts of material derived from various sources. This is more especially true in the case of the Lower Breccias and Sandstones and the Pebble-Bed. The material forming the marls, however, as might be expected from its finely comminuted nature, appears to have been supplied from an directions, and by a greater variety of rocks than those yielding detritus towards the formation of the other New Red sediments.
With regard to the source of the various mineral species it is most difficult to speak, except in certain cases; but, so far as can be judged, all the minerals detected in the New Red deposits, with the exception of staurolite, could be supplied by the older rocks of the West of England. The greater abundance of such minerals as blue tourmaline, topaz, rutile, and brookite appears to indicate that the rocks in which they occur were largely derived from the granite masses of Devon aud Cornwall, but more especially points to their attendant metamorphic rocks aud veinstones.
The garnets of the New Red deposits are clearly in no way dependent on the distribution of staurolite, but, on the contrary, are of most frequent occurrence in the northern part of the district where staurolite is less abundant. The fact that garnet, in the Pebble-Bed, makes its appearance together with an increased proportion of blue tourmaline, points to its derivation, at any rate in part, from the metamorphic rocks surrounding the West of Englnnd granites. Its absence from certain horizons might be accounted for, either by the direction of the sediment-bearing currents, or by the extremely local occurrence of garnets in the metamorphic aureoles of this district. It is only where subordinate calcareous bands of the Devonian and Carboniferous rocks and diabase-intrusions come within the influence of the granites that this mineral has been produced. It is not suggested that all the garnets in the New Red rocks were supplied by these metamorphic areas; but, should it be so, it would appear from the distribution of this mineral that all the New Red rocks of North Devon and West Somerset were formed in part of material carried from the west and southwest.
The Lower Breccias have always been considered as deposits derived from sources near at hand, for, as pointed out by De La Beche, Godwin-Austen, Conybeare and Phillips, and Mr. R. H. Worth, among the rock-fragments found in them are numerous examples of well-known rock-types present in Devon. The minerals and grains forming the finer material of these deposits point towards the same conclusion; but, in addition, especially in South Devon, they suggest strongly the influence of certain rock-masses non existent within the south-western area as now known. There is, also, nothing in the finer material to prove that the granite-masses themselves were undergoing denudation at the time when the Lower Breccias were being deposited.." [continues]
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Ussher , W.A.E. 1876. On the Triassic Rocks of Somerset and Devon. Quarterly Journal of the Geological Society of London, vol. 32, pp. 367-394.
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Warrington, G. 1991. The Lyme Regis Borehole, Dorset - Palynology of the Mercia Mudstone, Penarth and Lias Groups (Upper Triassic - Lower Jurassic). Proceedings of the Ussher Society, 9, 153-157.
By G. Warrington, British Geological Survey, Keyworth, Nottingham, NG12 5GG.
Abstract:
The Lyme Regis Borehole was drilled in 1901 but remains the only one in Devon and Dorset that has been cored through the lower part of the Lias Group, the Penarth Group and most of the Mercia Mudstone Group. Samples from 24 of the 50 levels from which core is extant have been examined for palynomorphs. Carnian (early Late Triassic) miospores from 287 m below the top of the Mercia Mudstone Group are the lowest such occurrence in the region, and may be only 100m above the top of the Anisian (early Mid Triassic) Otter Sandstone Formation of the Sherwood Sandstone Group. The Blue Anchor Formation, at the top of the Mercia Mudstone Group, yielded Norian(?) and Rhaetian (Late Triassic) miospores associated with acritarchs and foraminifer remains which give, 20.22 m below the top of the formation, the first indication of a transgression that resulted in the widespread establishment of marine conditions by the end of Triassic times. The Penarth Group has yielded Rhaetian palynomorph associations which are comparable with those documented from the group elsewhere in the British Isles and comprise miospores, dinoflagellate cysts and acritarchs. Palynomorph assemblages recovered from the Lias Group are dominated by conifer pollen.

Warrington, G. and Ivimey-Cook, H.C., 1992. Triassic. In: Cope, J.C.W., Ingham, J.K. and Rawson, P.F. (eds). 1992. Atlas of Palaeogeography and Lithofacies. Geological Society, London, Memoirs, 13, 97-104.

Warrington, G. and Scrivener, R.C. 1980. The Lyme Regis (1901) Borehole succession and its relationship to the sequence of the east Devon coast. Proceedings of the Ussher Society, 5, 24-32.

Warrington, G., Audley-Charles, M.G., Elliot, R.E., Evans, W.B., Ivimey-Cook, H.C., Kent, P.E., Robinson, P.L., Shotton, F.W. and Taylor, F.M. 1980. A correlation of Triassic rocks in the British Isles. Special Reports of the Geological Society of London, 13.


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Whitaker, W. 1869. On the succession of beds in the "New Red" on the south coast of Devon, and on the locality of a new specimen of Hyperodapedon. Quarterly Journal of the Geological Society, London,vol. 25, pp. 152-157. By William Whitaker, B.A. (Lond), F.G.S., of the Geological Survey of England.
[Example extract:]
The following account of the successive beds that are shown in the "New Red" cliffs of South Devon, is from notes taken during a holiday-walk along that coast last September, and it has been drawn up at the request of Prof. Huxley, in order to mark the stratigraphical place of the Hyperodapedon jaw from near Budleigh Salterton. I believe that the only paper which treats of the order of these beds is a full report of two lectures by Mr. Pengelly, F.R.S. To this I refer the reader for a more detailed account of the composition of the various "red rocks." Owing to the dip, lower and lower beds rise to the surface southwestward, so that an almost continuous section is given. The occurrence of the uppermost part of the "New Red" near the eastern boundary of the county, and its passage upwards into the Lias, have been noticed by Sir H. ;De la Beche, and more fully by Mr. Pengelly; but the cliffs here: are so much hidden by fallen masses, that little is to be seen below the "White Lias" until we pass to the west of the great landslip of 1839 at Dowlands. The cliff is then clearer, and shows a set of evenly-bedded greenish clays, with black shales, stone-beds, and layers of hard marl (Rhaetic Beds). Here Mr. Pengelly found the well-known bone-bed. Lower down some of the layers of clay have a reddish colour; and there is a passage downwards into "New Red" marl.. [continues]

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Woods, M.A. 2011. British Geological Survey (BGS). (Compiler Woods, M.A.) 2011. Geology of South Dorset and South-East Devon and its World Heritage Coast.

Special Geological Memoir for 1:50,000 geological sheets 328 Dorchester, 342 West Fleet and Weymouth and 342/343 Swanage and parts of sheets 326/340 Sidmouth, 327 Bridport, 329 Bournemouth and 330 Newton Abbott. Compiled by M.A. Woods. By Barton, C.M., Woods, M.A., Bristow, C.R., Newell, A.J., Westhead, R.K., Evans, D.J., Kirby G.A., and Warrington, G. Contributors: Biostratigraphy - J.B. Riding; Stratigraphy - E.C. Freshney; Economic Geology - D.E. Highley and G.K. Lott; Engineering Geology - A. Forster and A. Gibson. British Geological Survey, Keyworth, Nottingham, 2011. 161 pp. This is the new version of the Geological Survey Memoir for the Dorset Coast etc. and replaces Arkell (1947) and the earlier memoir by Strahan (1898). It covers a wider area than these old memoirs, though, and includes all of "Jurassic Coast", UNESCO World Heritage Coast. It is a key reference work and easily obtainable.
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Woodward , H.B. and Ussher, W.A.E. 1899. Excursion to Seaton, Sidmouth, and Exeter. Proceedings of the Geologists' Association, London, vol. 16, pp. 133-153. By Horace B. Woodward, F.R.S., F.G.S. and W.A.E. Ussher, F.G.S.
[Example extract - pp. 133-134]
"Twenty-eight years ago, Prof. James Buckman and Mr. J. Logan Lobley conducted an excursion of the Geologists' Association to the Yeovil district, and spent a short time on their fourth and last day along the cliffs east of Seaton. It seems strange, however, that forty years should have elapsed since the foundation of this Association before any expedition was made to the South Devon coast between Seaton and Exmouth, with its iringes of Blackdown Beds and its famous pebble-bed of Budleigh Salterton.
In 1889 an excursion was made to Lyme Regis, under the guidance of the present Director, and the members then advanced as far as the eastern portion of the Great Landslip. It was now planned to continue the exploration from the Landslip westwards to the mouth of the Exe.
On Thursday evening, March 30th, the members of the party, which numbered nearly forty, arrived at the Royal Clarence Hotel, Seaton. On Friday, March 31st, the members started at 9 a.m. along the esplanade to Axmouth Bridge, where the Director pointed out that the trend of the beach turned the outlet of the river eastwards, and had been the means of choking the harbour of the once flourishing little fishing-town. At the close of the last century, a large tract of salt marshes extended above Axmouth, but these had been drained to the advantage of the neighbourhood. In far earlier times, when the river was more potent in action, spreads of valley-gravel were laid down, and from these at Broom, in the parish of Hawkchurch, above Axminster, some fine palaeolithic implements, fashioned from Upper Greensand chert, had been obtained. Remains of Mammoth had been found in the Sid Valley, further west.
The party now proceeded by Squire's Lane to the lime-kiln beyond the Coastguard Station, where the Middle Chalk, zone of Rhynchonella cuvieri, had been noted by Mr. A. J. Jukes-Browne. This division cropped out along the 300 ft. contour-line. Several specimens of Inoceramus mytiloides and poor examples of the characteristic Rhynchonella were obtained. Passing on through Barn Close and Stony Close Lanes, a pleasant walk over the grassy Chalk-plateau, here, in places 400 ft. high, led to the western end of the Great Landslip at the Bindon Cliffs. The view eastwards through the chasm was grand and striking, the slipped masses of Chalk and Greensand forming a platform about 100 ft. lower than the cliffs from which they had broken away. As some account of this Great Landslip, which happened at Christmas, 1839, has already been published by the Association, no particular description need now be given.
Leaving the chasm, the members proceede4 a short distance westwards along the brow of the cliffs and descended by a foot-path to the shore a little west of Culverhole Point. Here in the low cliffs fringing the beach a fine section of Rhaetic Beds was exposed."
[continues]

Woodward , H.B. and Ussher, W.A.E. 1911. The Geology of the Country near Sidmouth and Lyme Regis. Memoirs of the Geological Survey, England and Wales. Explanation of Sheets 326 and 340. 102 pp. Second Edition. Price One Shilling and Sixpence. By H.B. Woodward, F.R.S. and W.A.E. Ussher, F.G.S., with contributions by A.J. Jukes-Browne, B.A., F.R.S. Published by order of the Lords Commissioners of His Majesty's Treasury. London, Printed for His Majesty's Stationery Office, by Darling and Son, Ltd., 34-40 Bacon Street, E., London.

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Copyright © 2017 Ian West, Catherine West, Tonya Loades and Joanna Bentley. All rights reserved. This is a purely academic website and images and text may not be copied for publication or for use on other webpages. Images and text cannot be used in any commercial activity, or any activity involving any financial gain. A reasonable number of images and text may be used for unpaid, non-commercial academic purposes, including free field trip handouts, lectures, student projects, dissertations etc, providing source is acknowledged.

Disclaimer: Geological fieldwork involves some level of risk, which can be reduced by knowledge, experience and appropriate safety precautions. Persons undertaking field work should assess the risk, as far as possible, in accordance with weather, conditions on the day and the type of persons involved. In providing field descriptions and guides on the Internet no person is advised here to undertake geological field work at any specific place or in any way that might involve them in unreasonable risk from cliffs, ledges, rocks, sea or other causes. Places need not be visited and the descriptions and photographs here can be used as an alternative to visiting. Individuals and leaders should take appropriate safety precautions, and in bad conditions be prepared to cancel part or all of the field trip if necessary. Permission should be sought for entry into private land and no damage should take place. Attention should be paid to weather warnings, local warnings and danger signs. No liability for death, injury, damage to, or loss of property in connection with a field trip is accepted by providing these websites of geological information. Discussion of geological and geomorphological features, coast erosion, coastal retreat, storm surges etc are given here for academic and educational purposes only. They are not intended for assessment of risk to property or to life. No liability is accepted if this website is used beyond its academic purposes in attempting to determine measures of risk to life or property.

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Dr Ian West, author of these webpages

Webpage - written and produced by:

Ian West, M.Sc. Ph.D. F.G.S. at his private address, Romsey, Hampshire, kindly supported by Southampton University,and web-hosted by courtesy of iSolutions of Southampton University. The website does not necessarily represent the views of Southampton University. The website is written privately from home in Romsey, unfunded and with no staff other than the author, but generously and freely published by Southampton University. Field trips shown in photographs do not necessarily have any connection with Southampton University and may have been private or have been run by various organisations.

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