West, Ian M. 2013. The Sandbanks Sand Spit or Sandbanks Peninsula; Geology of the Wessex Coast. Internet site: www.southampton.ac.uk/~imw/Sandbanks.htm. Version: 19th December 2013.

The Sandbanks Sand Spit or Peninsula - a geological field guide
by Ian West
Romsey, Hampshire, and:
Visiting Scientist at:
Faculty of Natural and Environmental Sciences,
southampton University,

Website hosted by courtesy of iSolutions, southampton University

|Home and Contents | |Field Guides - Introduction |Bournemouth Cliffs |Studland, South Haven Peninsula |Brownsea Island, Poole Harbour |Hengistbury Head |Bibliography of the Geology of Hengistbury Head webpage. |Highcliffe, Barton & Hordle Geology |Highcliffe, Barton & Hordle Coast Erosion |Studland, South Haven Peninsula

Click here for the full LIST OF WEBPAGES (You can download this educational site to SurfOffline or similar software to keep an offline copy, but note that updating of the live version takes place periodically. SurfOffline)

Click on images for large, high resolution versions!
(do not use browser zoom on the low resolution versions)

A general helicopter aerial view of the southern end of the Sandbanks Peninsula, the eastern part of Brownsea Island and also South Haven Point, Dorset, 6th July 2013

An aerial view of the Sandbanks peninsula, Dorset, as seen from a helicopter, flying north of the promontory, and looking southward, July 2013

An oblique aerial view of the South Haven Peninsula, Studland, Dorset, by Alan Holiday, June 2011

Poole Harbour in 1998, including Brownsea Island and the Sandbanks Peninsula, Dorset

Old oblique aerial photograph of the Sandbanks Peninsula, Dorset

Oblique aerial views of the Sandbanks Peninsula, Dorset, in 2008, courtesy of the Channel Coastal Observatory

A general aerial photograph of the Sandbanks Peninsula in August 2002, Dorset, courtesy of the Channel Coastal Observatory

A higher resolution aerial photograph of the southwestern part of the Sandbanks sand spit, Dorset, in 2004, courtesy of the Channel Coastal Observatory

Part of a notice board provided by the Council showing permitted usage of the beaches of Sandbanks, Dorset

A simplified map of the Sandbanks sand spit at the mouth of Poole Harbour, Dorset, also showing the location of the Sandbanks Borehole of 2002

Low angle sand beach without pebbles at Sandbanks, Dorset, February 2007

An excellent sand beach at the Sandbanks Pavilion, the central part of the Sandbanks Peninsula, Dorset, but with a promenade that is low in relation to a rising sea-level






Preliminary Note on Images

The Channel Coastal Observatory , National Oceanography Centre, southampton

In this webpage on Sandbanks some aerial photographs are shown. Most of these are reduced JPG versions based on high quality originals from the Channel Coastal Observatory, National Oceanography Centre, southampton (I have not changed them significantly apart from altering, for clarity, the sea colour from dull green to a more bluish shade). Many more aerial photographs of the Sandbanks area, perhaps almost 100, have been provided by this organisation. They arrange flights over the Sandbanks Peninsula at intervals and take more aerial photography. In addition these is much data on topography etc. Anyone wishing to make a serious study of Sandbanks geomorphology, beach processes, coast erosion, flooding risk etc should register with the Channel Coastal Observatory and examine their photographs and data.



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PART 1 - INTRODUCTION TO THE SANDBANKS PENINSULA continued
General

The Sandbanks peninsula is a sand spit ("The Sandbanks") consists of predominantly quartz sand derived from the cliffs of Bournemouth before the promenade and sea-defences were constructed at the beginning of the 19th century. The cliffs involved were west of Bournemouth pier and the sand was transported by longshore drift. The direction, from east to west, is unusual for the south coast of Britain because of prevailing southwesterly winds which drive waves from the southwest. This is also the direction of maximum fetch for much of the coast. The coast near Sandbanks is different; this is protected from southwesterly waves by the Harry Rocks - Ballard Point promontory and also by Durlston Head. The direction of maximum fetch is towards the southeast in this limited area, and this clearly explains how sand could have been moved to the Sandbanks spit. While most growth of the feature took place in the past before the building of Bournemouth sea defences cut off the main sand supply, the spit is not at present in a serious declining phase. Sand renourishment or replenishment has taken place on Bournemouth beaches in recent years and thus there is probably still some sand in the Bournemouth area that could travel here, if it can pass groynes. Coast erosion has been limited to certain parts and sea-defences at Sandbanks, especially rock groynes seem to have prevented serious damage. The rock groynes at the southern end of the peninsula seem to have functioned well. Unlike some other places, this is an area of natural accretion and sand-transit is limited and presumably only offshore down the Swash Channel. There is not much beyond in the direction of any possible sand transport so that terminal scour or terminal groyne syndrome may be less significant than elsewhere. In historic times there is little doubt that Sandbanks indirectly fed Studland with sand (via Hook Sand) but this has probably long ceased because of the deepening of the Swash Channel and the construction of the Training Bank. The question of loss of sand sand supply to the South Haven Peninsula is discussed in the South Haven Peninsula and Studland webpage. The use of Portland and Purbeck stone in the Sandbanks groynes is good. This rock is similar to that which fringes the coasts of the Isle of Portland and gives a fairly natural appearance; it is not as aesthetically as displeasing as can be some timber, iron and concrete constructions.

See also the webpage on the nearby Brownsea Island, Poole Harbour

Aerial overview of Brownsea Island in Poole Harbour, Dorset,UK, with some locations of mining and quarrying the mineral resources

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PART 1 - INTRODUCTION TO THE SANDBANKS PENINSULA continued
Access

There is easy access to the Sandbanks Peninsula by car, minibus or coach in the Autumn, Winter and Spring. It can be reached easily by public transport - buses from Bournemouth or Poole. Parking of vehicles is easy in the off-season when geologists and geomorphologists are most likely to visit.

This is not a place for the geologist or geomorphologist to visit in summer but it is good in winter. In summer its excellent beaches are fully in use for bathers and for children digging sandcastles and it is best left for the holiday-makers! You will have much difficulty trying to drive round the peninsula and parking may be impossible. If you do have to go in summer avoid a hot summer day; it is an easier place to visit in poor weather. Alternatively go to the Studland (South Haven) Peninsula , which is less crowded.

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PART 1 - INTRODUCTION TO THE SANDBANKS PENINSULA continued
Safety and Risk Assessment

Risks are very low at Sandbanks, except possibly in connection with the sea at the south end (Ferry Terminal area). There are no risk of falling rocks from cliffs, and the sea in the central part approaches a gently sloping beach with no extreme tidal range. Apart from possible road traffic problems this is a much safer place for groups of young people to study than are locations with steep cliffs. See also Studland (South Haven) Peninsula , which may be even better for school parties (for geographical or environmental studies comparison could be made between the undeveloped South Haven (Studland) Peninsula and the built-over Sandbanks Peninsula).

1. There is minor risk of falling on rock armour if one climbs onto this. Avoid going onto the rock armour.

2. With a field party there is risk of a road traffic accident if the group wanders across the busy road down the peninsula without taking sufficient care.

3. Be careful at the south end end where the sea approaches seawalls rather than beaches. The tidal current here is very strong and no-one should enter the water here. Take care not to slip off seawalls.

4. Water activities are not considered here. They are not usually part of a geological or geographic field course they have their own particular risks.

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PART 1 - INTRODUCTION TO THE SANDBANKS PENINSULA continued
Geology

Geological maps showing comparison of the Sandbanks Peninsula and the Weymouth Peninsula, Dorset

Old geological map of the Studland and western Poole Bay area

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PART 1 - INTRODUCTION OT THE SANDBANKS PENINSULA continued
Beach Sediment

High intertidal beach sediment at the southeastern part of Sandbanks, Dorset

In most of the pictures above notice particularly the almost complete absence of flint pebbles which are numerous on the main Bournemouth beaches, in addition to the sand, and which increase in abundance eastward towards Hengistbury Head. However, as shown in the image directly above, some brown, subangular flint pebbles do occur in association with bivalve shells in the high intertidal zone (effectively the "trash-line"). They are almost confined to this level. The pebbles are typical of the subangular flint pebbles of the Pleistocene, fluvial, periglacial, terrace gravels (the Plateau Gravels) such as occur in the upper parts of the cliffs of Bournemouth. The pebbles here though are relatively small and much larger examples occur in the gravels of the cliffs.

In the photograph the bimodality of the particle size distribution of the sediment is mentioned. Most of the Sandbanks sand is unimodal (with one particle size mode or peak). This sediment is bimodal because there a sand-size mode or peak and in addition a pebble-size mode or peak but not a range of sizes in between. These comments are made just from observation and not from a size-size analysis, but it is fairly obvious to the eye how the particle-size histogram would appear. Most of the sand at Sandbanks is, like that at Studland, very mature and dominantly quartz. The sediment shown in the photograph above is unusual in containing some shell-carbonate debris, which appear as white grains. Because most bivalves are of aragonite (although oysters are calcite) it is probable that aragonite is the main mineral constituent of this, but it is not been tested by X-ray diffraction. There are also black grains which may be either lignite from the Tertiary deposits in the cliffs or possibly coal debris because much coal was once shipped into Poole Harbour. This needs closer examination.

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PART 1 - INTRODUCTION TO THE SANDBANKS PENINSULA continued

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PART 2 - HISTORY OF THE SANDBANKS PENINSULA
Late Pleistocene (Devensian) History

The Pleistocene palaeovalleys made by rivers flowing across Poole Bay and Christchurch Bay, English Channel, modified after Velegrakis et al. 1999

The Sandbanks sand spit is a barrier beach at the mouth of Poole Harbour. Not long ago in geological terms, about 10,000 years BP the English Channel was dry and southern England was in periglacial conditions. There was glaciation to the north of a line north of London to about Bristol. The Flandrian Transgression or flooding of the English Channel was the result of global warming and melting of the ice and warming of the sea. As is well-known the process is continuing now. The present rivers of the area, such as the Frome and the Piddle, the Stour and the Avon and even the Bourne Stream are the upper remaining relics of longer rivers which originally extended down the dry land of the English Channel to join the river Seine. The old valley or palaeovalley of the Frome and the Piddle was beneath the southern end of Sandbanks sand spit. This is shown in the map above, based on the impressive work of Velegrakis, Dix and Collins (1999). As the river valley flooded with the rising sea level the cliffs of Poole Bay were cut back and an early spit moved back in a northwesterly direction. It is natural for the Sandbanks spit to move in this direction but for the moment it is fixed with sea-defences and the cliffs of Bournemouth are held for the present by a seawall and promenade.

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PART 2 - HISTORY OF THE SANDBANKS PENINSULA
1585-1610 - Old Maps

The North Haven Peninsula, Sandbanks, and the South Haven Peninsula, Studland as shown on part of Ralph Treswell's map of the Isle of Purbeck,  1585-6

Treswell's 1585-1586 map of the South Haven Peninsula area, Studland, of Sandbanks and part of Brownsea Island, with some additional interpretation and notes

A 1610 map of Dorsetshire showing the Sandbanks sand spit having the same general morphology as at present

These old map from 1585 and 1610 shows that the Sandbanks sand spit had already developed into something similar to its present general morphology at this early date. In 1585 the southern end may not have enlarged to the present extent and if this was the case then Branksea Castle, on Brownsea Island, would have had a direct view down the main Swash Channel.

In relative terms the Sandbanks sand spit is quite old and has not changed greatly. It is quite a stable spit for the region and thus resembles Calshot Spit at the mouth of southampton Water. Presumably, though, as is normal for spits and barrier beaches in the region (e.g. Hurst Spit, Mudeford Spit and Chesil Beach) it should have "rolled over" landward to some extent as the adjacent cliffs, those of Poole Bay, retreated. It would be expected, of course, to roll over again in the future in normal, natural circumstances as Poole Bay enlarges. However, Sandbanks spit is held almost static at present. This is largely because of the Bournemouth sea defences which have, so far, have held the cliff line static. In addition there are local sea defences, such as rock armour groynes, on the Sandbanks sand spit.

This old and fairly static nature of the Sandbanks spit would not be an unusual situation were it not for the fact that the nearby South Haven Peninsula (Studland) has changed drastically by accretion. A major movement of sand to this region to the southwest has occurred without significantly affecting the form of the Sandbanks Peninsula. This is quite surprising and indicates special and complicated transport paths for sand in the region.

Since the 17 century it is likely that the southern end of the Sandbanks spit has enlarged. In addition the "sandbanks", that is the sand dunes have developed. These were relatively large in the central southern part of the peninsula. They are now almost all concealed under buildings (and gardens) of the 1920s and 1930s and later. Even though there is not much panorama now from Panorama Road, it is still a pleasant place and it has nice vegetation with many mature pine trees. I know it from childhood days and the broad sandy beaches on the eastern side are as excellent as ever.

It would be wrong, however, to consider the spit as some permanent peninsula that is unaffected by the sea. The last major hurricane, like Hurricane Katrina, was 1824, but little is known about events just here. Some very circumstantial evidence is mentioned below. It is clear from the maps that the spit did not change in shape to any great extent and that is a good omen for the future.

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PART SB2 - HISTORY OF THE SANDBANKS PENINSULA continued
The 1824 Hurricane and English Channel Storm Surge

English Channel Hurricane of November 1824 - Map showing the effects on Devon, Dorset and Hampshire

There seems to be no specific information about Sandbanks in the 1824 hurricane and storm-surge. As the old maps show it was not been a developed place until recently, and therefore does not have as much recorded history as that of the similar sand spit at Weymouth. (Note that the heavy development of Weymouth and expansion towards the Radipole Backwater tends to obscure the fact that the northern end was originally a narrow sand bar, "The Narrows", like the neck of the Sandbanks peninsula.)

The main problem with this storm was the very severe winds blowing into the English Channel banked up the sea water into a "storm surge". This is a normal of major hurricanes. The sea-level can rise up to 3 or 4 metres above normal levels in extreme cases. This was observed at Lyme Regis in the 1824 event, and this was the major cause, with wave action, of the Weymouth flooding.

Sandbanks may be less affected than Weymouth in a 1824-type hurricane, but it not possible to be sure. It has some fairly high sand dunes in the southern part, is to some extent sheltered by the Purbeck Hills and may suffer somewhat less from being further east down the English Channel. As noted above the old maps show the peninsula as having the same general form so it has not been changed drastically. However, the extent of flooding is a problem. The wrecking of a ship up on farm land at Parkstone and the flooding of Poole shows that the sea or harbour level was temporarily very high. Thus it is likely that there was flooding on the Sandbanks spit in the 1824 hurricane, but there is no record of just how much was flooded and how deep was the water.

For more information on the 1824 hurricane and storm surge see Chesil Beach Storms.

The entrance to Poole Harbour between Sandbanks and the South Haven Peninsula (Studland) - comparison of older and newer charts

This comparison of charts shows some of the changes which have taken place from when Sandbanks was a natural area of sand-dunes to its more recent developed state. There have been significant changes in the offshore topography. The southeastern end of the Sandbanks sand spit shows clear evidence of deepening water and of some erosion occurring. This is still an area of interest with regard to loss of sand.

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PART SB2 - HISTORY OF THE SANDBANKS PENINSULA continued
1850s-60s
Brannon's 1860 map of Poole Harbour, Sandbanks and Studland etc, Dorset, with his plans for development

Shown above is Brannon's (1860) map of Poole Harbour, Sandbanks, Studland etc. with his plans for further development. The Training Bank was proposed and built, but other proposed schemes have not necessarily taken place in accordance with the original plans.

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PART 2 - HISTORY OF THE SANDBANKS PENINSULA continued
1890s

Part of an 1892 four inch to one mile, geological map showing Poole Bay, Sandbanks, Studland, Bournemouth and Hengistbury Head

The map shown above is part of an 1892 geological map, based on an earlier topographic map. It is enlarged here and thus too much attention should not be paid to the finer detail in terms of the shape of the Sandbanks sand spit. The peninsula is much the same as at present. This is in contrast to the Studland, South Haven Peninusula which has the Little Sea still connected to the open sea of Poole Bay.

The Borough of Poole has referred, on a notice board, to groynes emplaced in the 1890s.

"To prevent the sea breaking through the Sandbanks peninsula and forming a second Harbour entrance, a series of 13 groynes was constructed in the 1890s. From then until the 1950s Sandbanks beach steadily became wider, allowing much of the development which we see today. In the 1950s, the old groynes were decayed, and seen as a danger to public safety, so they were removed."

Thus in spite of the fact that there has been little overall change in the general shape of the peninsula, there has been some concern coast erosion for a long time.

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PART SB2 - HISTORY OF THE SANDBANKS PENINSULA continued
1930s - Sandbanks, a Holiday Resort

A crowded beach at the the Sandbanks Pavilion, Dorset, in summer 1934

In the 1920s and 1930s the Sandbanks sand spit was developed as a holiday resort. The Pavilion, the building at the main entrance to the sand beach, was built 1928. In summer the soft sandy beach became crowded, as it is in summer now. If you examine the photograph you will notice that the beach is quite wide but probably not as wide as at present. This is long before the construction of rock armour groynes.

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1940s - 1950s

An old topographic map of the Sandbanks Peninsula, Dorset, probably from the 1940s or 1950s

This map from the 1940s or 1950s shows a general shape of the peninsula similar to that of today with many of the present buildings. There are differences of detail regarding roads.

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PART SB2 - HISTORY OF THE SANDBANKS PENINSULA continued
2000-2001 - Major Sea Defence Works

Notice at Sandbanks, Dorset, part 1

Notice at Sandbanks, Dorset, part 2

The notice shown above was seen on 1 Jan 2004, but has been placed there at an earlier year. It includes a note stating that the work commenced in November 2000 and should be finished by April 2001. The 1.3 million pound project was funded by the Ministry of Agriculture and Fisheries. At the bottom are the logos of the various organisations involved which include MAFF, HR Wallingford, PHC, Environment Agency, English Nature, and Halcrow. See the website Coastal Protection Works at Sandbanks - Borough of Poole , for more information (or go to Borough of Poole main website and use the search box).

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PART SB3 - FUTURE OF THE SANDBANKS PENINSULA

Sand Sediment Transport - Present and Future

Present sand sediment transport on the beaches of Poole Bay, Bournemouth, Dorset, and possible implications for the Sandbanks Peninsula in the future

Sandbanks, of course, is dependent on beach sand transport. For technical information on this topic go to:

SCOPAC - Sediment Transport. SCOPAC - Standing Conference on Problems Associated with the Coastline. There are many sections in this important publication. There is a an index map at: Sediment Transport Study - map showing areas.

More specifically for Poole Bay, Bournemouth and Sandbanks visit the map with detailed sediment transport information at:

Poole Harbour Entrance to Hengistbury Head">

In general terms the sandy beaches of Bournemouth and Poole Bay have derived their sand from the erosion of the Eocene strata in the cliffs. Sandbanks has in particular resulted in part from a good sand supply from the Branksome Sands, forming the cliffs of the western part of Poole Bay, particularly from Durley Chine westward. The Branksome Sand Formation is 70m thick; it takes its name from Branksome Chine [SZ 069090] and is of Bracklesham age Bristow et al. (1991).

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PART 3 - FUTURE OF THE SANDBANKS PENINSULA

Global Warming - Sea Level Rise

A plot of indicators of former sea levels so as to show the sea-level rise over the last 9000 years in southeast England, modified after Devoy (1982)

This diagram, modified after Devoy (1982) shows how the Mean High Water Spring Tide sea-level has risen in southeastern England over the last 9000 years. Compare with the log of the Sandbanks Borehole. There was a rapid rise many thousands of years ago but this reduced to a steady rise for the last few thousand years.

With regard to the future sea level a significant additional sea-level rise is expected as a consequence of global warming. See Intergovernmental Panel on Climate Change (IPCC) . 2007. Climate Change 2007: The Physical Science Basis.

Future sea level rise estimates for the Wessex coast

The table here is from this publication by IPCC. It provides an indication of possible rates of sea level rise over the next hundred years. Something like half a metre of relative sea level rise seems probable in this region, but the real figure could be higher. There is some local downwarping in the Wessex area resulting from isostatic rebound (melting of the ice in the north, with uplift in northern UK, and downwarping in the south). This increases the relative rate of sea level rise in the local area. In any case global warming is likely to be much more important.

It should be emphasised that nothing dramatic has happened in the last few hundred years to the sheltered Sandbanks area, and the spit has a very long history back to at least 1610. Most of it seems unlikely to flooded by just sea-level rise for about 200 years (or at least 150 years), although the additional and more serious effect of storm surges has to be taken into account. The sand spit seems to have survived the 1824 storm surge (and presumably some flooding) with little if any change in outline. If any parts of it are too low and or too narrow for future conditions then presumably those parts could eventually be raised and enlarged without too much difficulty, if that was necessary. Fortunately, much of the housing on the sand spit is quite high on the old "sandbanks" and may well above the flood range of the most extreme storm that is theoretically likely. Erosion seems to be under control at the present.

PART SB3 - FUTURE OF THE SANDBANKS PENINSULA continued
Washover Risk

The central, Pavilion area of the Sandbanks sand spit, Dorset, showing a low area between sea and harbour

General view of the low harbour side of the central part of the Sandbanks sand spit, Dorset

Present estimates of sea-level rise applied in a very approximate manner to the harbour wall opposite the Pavilion area, Sandbanks, Dorset, photo 23 February 2007, normal conditions

It is obvious that an area of the Sandbanks Peninsula near the Pavilion and the main car park is relatively low in relation to sea level. Estimates of sea-level rise from global warming and local downwarping suggest, though, that it might take about 200 years before the normal high tide level was up to the road just here. This is a long time away and might be ignored for the present.

However, the slow progressive rise of sea-level is not the only risk. A greater problem is that of temporary surges of sea-level caused by great storms blowing into the English Channel and backing-up the seawater (like the East Coast Floods - 31 Jan 1953). These are very rare, but sea level can rise about 1 metre above high tide to up to 3 metres or more in extreme hurricanes (e.g. as at Lyme Regis and the Chesil Beach in 1824). However, it might be possible that global warming could produce climatic changes that make such hurricanes and associated storm surges more likely. The risk of a temporary surge of sea level due to a storm being added to rising sea-level is the real hazard to a low-lying area like this. Temporary flooding would be the result. Storm surge flooding may occur in any case at very rare intervals, possibly at about 1 in 250 years or more. The important question is whether it is likely to occur more frequently as a result of global warming.

On the Sandbanks Peninsula any flooding of the low road here is worth observing and noting as an indicator of events. Some other parts of the peninsula are higher, particularly the areas of high sand dunes in the southern central part. It should be noted that because of the sheltering of the Sandbanks Peninsula by the Headland and hills of Ballard Down and Handfast Point the sandspit is not greatly at risk of breaching (except in most extreme circumstances) only of temporary flooding in parts under certain rare conditions.

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PART SB3 - FUTURE OF THE SANDBANKS PENINSULA continued

Oil and Gas Extraction Methods from the Underground Oil and Gas Reservoirs

Part of the Sandbanks Peninsula is over at least the Sherwood Sandstone Reservoir, the major reservoir of Wytch Farm. At least two extraction boreholes with large pumps underlie the end of the peninsula. Oil and gas extraction in a area may have little or almost no effect. In some parts of the world (e.g. Gulf of Mexico) extraction has eventually led to subsidence.

The Bridport Reservoir, the upper reservoir has had Poole Harbour water injected into it for decades but not at very high pressure. This has been successful and trouble-free and has helped in extraction oil and gas.

The deeper Sherwood reservoir might, perhaps, in present late stage of the oilfield (continuing until at least 2020) need much higher hydraulic pressures. There has been the unconfirmed suggestion recently of raising hydraulic pressure in the lower, the Sherwood Reservoir to a very high level by pumping in large quantities of sea water. Very high hydraulic pressure could open up pathways underground for more oil to reach the extraction pumps. It is not known whether this will happen and apparently permission from the council would be needed for this to take place. Note that this hydraulic activity would not be hydraulic fracturing of shale, but the hydraulic opening up of the sandstone reservoir. It must be emphasised that this is not a plan for Shale Gas Hydraulic Fracturing or "Fracking", and it would not be in shale or primarily for gas. It is just to improve the permeability of the oil reservoir. With regard to gas, this has long been produced from Wytch Farm oilfield and is piped away to Sopley, near Bournemouth, where it enters the normal gas main system. This is another benefit from the Wytch Farm oil field, very successful commercially and environmentally.

It is not know whether there has been any effect of the oilfield activities on the precise level of the south end of the Sandbanks Peninsula. Is it static, rising or lowering? No change is obvious. It is believed that some recent work involving SAR, Synthetic Aperture Radar, might be taking place in the Wytch Farm region. This can reveal very small changes in surface level. The writer has no detailed information on anything relating to either water injection or SAR, and awaits further news in the future (very high pressure, sea water injection into the Sherwood Reservoir by Perenco UK, to open up, fracture and improve the reservoir in its present later stages has been under discussion in mid 2013).

Large scale oil and gas production from Wytch Farm oilfield seems to continue to be successful, generally trouble-free and almost invisible. Its effect on the environment is minimal and most people know little about it size, its success or its detailed activities.

[In true perspective, any industrial activity in the Sandbanks area is probably of small significance compared to the old and fundamental matter of whether permanent buildings houses should have been built on a harbour mouth sandspit. In some respects the Poole Harbour sand spit has similarities to Dawlish Warren, the sand spit at the mouth of the Exe Estuary. Both have had their cliff sand source supplies cut off, but Dawlish Warren is undergoing much faster erosion. That, though, does not have the problem of many permanent buildings, the peculiar feature of the Sandbanks spit. The buildings have not been at Sandbanks long enough to have encountered the rare hurricances that can hit this coast (e.g. 1703, 1824). Sooner or later natural events may make oil industry activities seem of very small consequence.]

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SB. Hurricane Risk - Comparison with a Florida Barrier Island

Fortunately, Sandbanks is not normally affected by hurricanes, mainly because, as noted above, they are very rare in this region. However, they can occur perhaps once in 250 years or longer. In addition, again as noted above, Sandbanks is relatively sheltered by Harry Rocks, Ballard Point etc. and the Purbeck Hills.

If a hurricane does occur, though, and can affect this area it may produce some similarities to the effects on Florida sand barrier islands. Santa Rosa, near Pensacola (Florida Panhandle) is a very large barrier island. However the western end resembles the Sandbanks penisula and is on a smaller scale. Because Santa Rosa Island is in the Gulf of Mexico it is of course much more at risk of hurricane activity.

See the effects of hurricane-produced washover:
Washover damage at Santa Rosa Island.

More information is available on the USGS webpage: Coastal Change Hazards: Hurricanes and Extreme Storms: Hurricane Ivan; Pre- and Post-Storm 3D Topography - Florida Coast. Before and After Photo Pairs.

For technical information on the survival or loss of sand dunes during a hurricane on the Santa Rosa barrier island see:

Claudio-Sales, V., Wang, P. and Horwitz, M.H. 2008. Factors controlling the survival of coastal dunes during multiple hurricane impacts in 2004 and 2005: Santa Rosa barrier island, Florida.

This paper may also be useful with regard to the South Haven (Studland) peninsula.

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Coastal Erosion Problems - Solidarity Fund and Leasing Discussion

For some new discussion about coastal erosion and compensation see Nowell (2008) - Coastal land is only leased from the sea, Guardian Newspaper, April 21, 2008. David Nowell, a Fellow of the Geological Society, has noted that there is no solidarity fund to compensate people in Britain from loss of houses due to coast erosion or sea-flooding. He has suggested that any land likely to disappear within a century should become leasehold and the time stated on the title deeds. He considers that there should be a solidarity fund. More details regarding the suggestion are in his letter. It is a brief but stimulating article and should provoke discussion on policies for dealing with the expected effects of future erosion and sea-flooding on the British coasts.

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PART SB4 - LOCATIONS ON THE SANDBANKS PENINSULA
SB4.1 Sandbanks to Flaghead Chine

Removal of Contaminated Sand in 2004

Erosion of  dark, muddy  sand, Flaghead Chine, Dorset Details of erosion of the contaminated sand, looking towards Sandbanks, Dorset

Erosion of grey contaminated sand between Flaghead Chine and Sandbanks, Dorset

Close view of the grey debris on the beach at Sandbanks, Dorset

As observed in January 2004, the beach between Flaghead Chine and the beginning of the Sandbanks peninsula had recently received some new grey material tipped on top of the existing beach sand. This deposit was of soil-contaminated sand perhaps with some old estuarine clay It contrasted conspicuously with the natural beach sand because of its, darker, medium grey colour. It contained bricks and pieces of concrete and other human artefacts and is believed to have come from a building site on the harbour side of the Sandbanks peninsula. The photographs here were taken after a major storm had occurred on the night of the 7 January 2004. This seems to have eroded part of the dark impure sand, the limit of erosion producing a small cliff on the beach. (as seen at low tide at 3.30pm on 8 January 2004).

On the 21 Jan 2004 the local radio station Wave 105 reported that this dumped material has been found to be contamined with asbestos. Apparently the material was deposited on the beach in October 2003, the intention having been to reduce problems of erosion with what was thought to be clean sand.

The following article was published on a webpage of the Bournemouth Daily Echo: Poole News .

"This states that fences have gone up around one of Poole's prized Blue Flag beaches while health inspectors attempt to discover the extent of asbestos contamination. Poole Council is working with the building contractors who dumped the contaminated sand on the beach at Flaghead Chine to clear up the toxic material as soon as possible."

Beach Clean-up Begins

On 28 January the following report was given by the Bournemouth Daily Echo website:
'Work on clearing 1,000 tonnes of contaminated sand from one of Poole's top beaches has now begun. Specialist contractors have been brought in after the discovery of a small piece of cement containing asbestos on a section of beach between Shore Road and Flaghead Chine. Over the next two to three weeks a 360-degree excavator will remove the sand recently placed on the beach by local building contractors....' [continues]

See also

Council chief in firing line on beach asbestos - by Melanie Vass. Bournemouth Evening Echo webpage, 28 Jan 2004.

The beach near Flaghead Chine, Sandbanks, Dorset, in October 2004.

After the above reports were published by the media, the remaining contaminated sand was removed by the council and the beach has returned to its normal clean condition. The photograph above, taken in October 2004 shows a pleasant sandy beach with blown sand travelling northeastward across its surface. The beach is once again of its usual excellent quality in terms of amenity.

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PART SB4 - LOCATIONS ON THE SANDBANKS PENINSULA

4.2 The Northern Part - the Narrow Neck

The narrow part to the main part of the Sandbanks Sand Spit, Entrance to Poole Harbour, Dorset, helicopter view, 6th July 2013

The narrow neck of the Sandbanks sand spit, Dorset, aerial view, courtesy of the Channel Coastal Observatory, 2002

View towards the neck area of the Sandbanks sand spit, Dorset, on a wet day when the sea was rough but not extreme, 4 March 2007

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PART SB4.2 - LOCATIONS ON THE SANDBANKS PENINSULA

4.2 The Central Part - Pavilion Area

A helicopter view of the central part of the Sandbanks beach, Dorset, where there is some sand loss by longshore drift towards the northeast, photograph 6th July 2013

The central, Pavilion area of the Sandbanks sand spit, Dorset, showing a low area between sea and harbour

The beach on the seaward side of the centre of the Sandbanks peninsula, Dorset View from rock groyne, east side of Sandbanks peninsula, Dorset

This central area, near the Pavilion, has very good wide sand beaches. These are between rock armour groynes of Portland Stone (and basal Purbeck strata). There is only limited indication on the beach of any serious erosion and that is towards the northeast. Groynes, as shown in the uppermost photograph above have sand accumulations on the southwest side showing sand movement away to the northeast, towards Bournemouth. This has been recorded in 2003 by the council. It is known that Sandbanks will loose sand and be damaged or broken without periodic artificial re-nourishment. It is not a naturally stable place now.

A minor matter is that at times, sand blows away to the northeast. Some plastic barriers have been erected to try to reduce sand loss by the development of sand dunes. The place has had some complex natural developmental history and is now a potentially beach-loosing area (although not necessarily at a fast rate). The loss situation has been known, at least since 2003.

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PART 4 - LOCATIONS ON THE SANDBANKS PENINSULA
4.3 Southern Corner of Sandbanks Sand Spit

A helicopter view of the channel at the Chain Ferry, southern Sandbanks Peninsula, Dorset, 7th July 2013

Wide sand beaches decreasing in width towards the SW, at the end of the Sandbanks sand spit

Southeastern coast of the Sandbanks Peninsula, Dorset, near the southern end, showing areas where there are sea walls and groynes but less beach sand, photograph courtesy of the Channel Coastal Observatory

The beach diminishes at the southern end of the Sandbanks peninsula, Dorset, and there a transition SW to sea walls

The southern end of the Sandbanks Peninsula, Dorset, in August 2002, showing possible underwater sand transport, photograph courtesy of the Channel Coastal Observatory

Sand accumulation at the southern part of Sandbanks peninsula, Dorset Evidence of sand accumulation, southern part of Sandbanks peninsula, Dorset

The southeastern coast of the Sandbanks Peninsula shows beaches decreasing in width towards the southern tip of the peninsula. Towards the ferry terminal there is complete depletion of beach sand and the southernmost coast adjacent to the channel has robust sea walls as a margin. The aerial photographs above, courtesy of the Channel Coastal Observatory, suggests the possibility that the flood tide is transporting some sand from here into Poole Harbour.

Sea wall in front of the Haven Hotel, south end of the Sandbanks sand spit, Dorset, photo 23 Feb 2007

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PART 4 - LOCATIONS ON THE SANDBANKS PENINSULA
The Ferry Terminal

Ferry terminal at Sandbanks, Dorset Sandbanks ferry at sunset, looking southwest across Poole Harbour

Sandbanks ferry from the ramp on the Shell Bay side Sandbanks ferry from Shell Bay, Jan 2003

The photograph at the top show the chain ferry and terminal at Sandbanks for transport across the entrance to Poole Harbour to Shell Bay and Studland. Notice the Purbeck hills of Chalk in the distance in the top right photograph. The other, lower, images are of this southern edge of the Sandbanks sand spit as seen from South Haven Point, on the Studland side. A strong ebb current flows out of Poole Harbour and the ferry has to be held in position by large chains. The present channel is not on the site of the ancient river channel prior to the rise of sea level (the Flandrian Transgression). The old buried channel is further north and beneath the southern part of the Sandbanks Peninsula, where it has been encountered in a borehole. Sandbanks sand spit has pushed the entrance channel of Poole Harbour to the south. Such migration of spits across a channel is known elsewhere. Calshot Spit on southampton Water, for example, has extended eastward across the old river channel there.

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PART SB4 - LOCATIONS ON THE SANDBANKS PENINSULA
The Harbour Side at the Southern End

The harbour side of the southern part of the Sandbanks sand spit, Dorset, with a small beach of sand and flint pebbles, 2002

View from the Sandbanks Peninsula, Dorset, across to Brownsea Island, 2002

Branksea Castle  photographed from Sandbanks, using a telephoto lens and thus including some distance compression, 2002

The harbour side of the southern end of the Sandbanks sand spit has mostly no public access. The gardens of houses extend down to the harbour, from which there is a view of Brownsea Island. There is a small beach, mostly covered by high water, and at low tide this can be seen to have both sand and some flint pebbles. The pebbles have presumably reached this location by longshore drift in the past from small cliffs of Pleistocene flint gravel within Poole Harbour, particularly the Lilliput area. In the respect of containing pebbles the harbour beach differs from the outer purely sand beach. This side of Sandbanks sand spit is not subject to major wave action, and sea walls are normally only needed against flooding rather than large waves.

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PART SB5 - THE SANDBANKS BOREHOLE - 2002

Introduction and Borehole Log

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The Sandbanks Borehole, 2002, proved that the sand spit is over a buried channel and has pushed the mouth of Poole Harbour southward

Borehole at Sandbanks, Dorset, into the Pleistocene buried channel, 2002

Log of the Sandbanks Borehole, September 2002, into the buried channel of the Pleistocene Frome-Piddle river system

In September 2002 a cable percussion borehole was made for civil engineering purposes on Sandbanks opposite Brownsea Island. The location was at 88 Panorama Road, within a large garden and close to the shore, opposite Brownsea Isand. The borehole was for Halcrow , the major civil engineering company, in connection with investigating the strata from Sandbanks to Brownsea Island so that a pipeline could be established between the two. It was drilled by Foundation and Exploration Services Limited, Basingstoke and geologically logged by Amanda Lane.

The Pleistocene palaeovalleys made by rivers flowing across Poole Bay and Christchurch Bay, English Channel, modified after Velegrakis et al. 1999

Flint gravel from the Sandbanks Borehole, 2002

This borehole penetrated down to the Pleistocene buried channel which had already been recognised on the basis of geophysical work by Velegrakis et al. The base of the channel here is at about minus 23 metres. Above the periglacial river gravel is a Flandrian peat at a depth of about 16 to 17 metres below OD. This is quite a deep Holocene peat.

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PART 5 - THE SANDBANKS BOREHOLE - 2002

Comparison with the Lower Hamworthy Borehole, Poole

A borehole at Lower Hamworthy, Poole Harbour, Dorset, was briefly mentioned by Godwin, Suggate and Willis (1958) and Devoy (1972). There is freshwater peat, sample Q 181, is from minus 12.8 metres (42 feet) below sea-level overlain by a marine clay at -11.5m. O.D.

Unfortunately, there has been some confusion about the age of the peat. Godwin, Suggate and Willis (1958) erroneously gave the date as 7348 BP - i.e. before the present - and not 7348 BC as should have been stated. Devoy (1981) pointed out the error. The peat should be 7348 years BC and consequently about 9298 BP (for 1950). A further complication is that the pollen assemblage actually places the peat in Pollen Assemblage Zone VIb which corresponds to 7700 BP Devoy (1981). Thus the dating of the peat is rather problematical but it is obviously very old.

In any case just the dating of the peat does not necessarily provide specific evidence for former sea level. Peat could be forming in rather higher reaches of a stream valley while the sea level is lower (as in the New Forest at the present day). Old peat deposits are at various levels and do not, of course, have to be far below the present sea level or even below present sea-level at all. At southampton Western Docks, for example, there are very old Holocene peats at only about 6m. below OD (Godwin and Godwin, 1940)and they are higher at Redbridge, southampton.

If the peat at Lower Hamworthy is somewhere near 8000 years BP then it does prove that the sea had not reached -12m. by that date (not surprising). The coast was then somewhere further out in what is now the English Channel. The peat in the Sandbanks Borehole is deeper at about - 16m. It has not been dated, but it would not be surprising if was not similarly many thousands of years old.

A marine clay overlies the peat at minus 11.5 m. O.D. at Lower Hamworthy. Similarly at Sandbanks a marine clay that seems to be a saltmarsh deposits overlies the peat at -16m and in this case extends up to -12.7m. The marine clay has not been dated at either locality.

Another borehole record for Poole Harbour comes from Keysworth which is northeast of Wareham. This is a record from shallow depths. There is evidence of marine transgression of a coastal peat bog at -3.01m. in Atlantic times of about -5500BP. For comparison it worth noting that there has been a marine transgression of a ("Neolithic") peat at Fawley, Hampshire, at about -3m, but to top of that peat is younger at about -3689BP Hodson and West (1972). The thin clay bed in the Sandbanks Borehole at 3.6m may well correspond to a fairly late Flandrian (Holocene) marine transgression like that at Keysworth. There is widespread marine flooding in the region of peats of about Neolithic age. Some submerged forests are of this origin. If the clay bed really is of this origin, and this is only a matter of speculation at the moment, then the Sandbanks sand spit is very old, many thousands of years old. It is quite possible though that the spit is young and that the clay bed has some different origin.

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LINKS: Some Relevant Websites (see also the main reference list)

Coastal Protection Works at Sandbanks - Borough of Poole. Extracts: "At the beginning of the century, the Sandbanks Peninsula area consisted entirely of sand dunes apart from two coastguard cottages built in 1850 and a few wooden holiday homes. Sandbanks was part of the Wimborne Estates and during the 1910ís, the first plots were sold off and a few permanent homes were built. In post war times, the building of luxury residence with their own waterfront and slipway has escalated with the final infilling of smaller houses, bungalows and blocks of flats. Less than half the dwellings are used throughout the year as permanent residences, the rest are used as holiday flats and second homes. In 1929, the whole of the beach and present recreation ground consisting of 13 acres were purchased from the Estate for the sum of £13." .. "Recent Coastal Protection Work. Phase 1. Due to the increase in the erosion rate and the perceived threat to properties, specialist consultant HR Wallingford was commissioned to produce a design for a coastal protection scheme to deal with the rapidly worsening situation. The scheme chosen built on the partial success of the Midway Path groyne and consisted of four addition rock groynes, one to the west of Midway Path and three to the east. [continues]. [This website is recommended. In case of any difficulty in obtaining it go to the Borough of Poole main website and use the search box. ]

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ACKNOWLEDGEMENTS

I am particularly grateful to the helpful staff of the Channel Coastal Observatory for allowing me to use their excellent aerial photographs of the Sandbanks Peninsula. I very much appreciate the help of Travis Mason, and for the oblique aerial photographs of the Sandbanks Peninsula, the work of Chris Moulton, GIS Analyst. I thank Alan Holiday for an oblique aerial photograph of the Poole Harbour entrance and part of the Sandbanks Peninsula. I very much appreciate the kind permission to examine the Sandbanks Borehole given by the geotechnical staff of Halcrow , the major civil engineering company, with whom I had some geological discussions. I am very grateful to Foundation and Exploration Services Limited, Basingstoke for kind permission to go on site, visit their borehole and examine samples. I particularly thank Amanda Lane, the site geologist for kind cooperation on site and for borehole information. It was good to be able to discuss the borehole with her at the time. It was very generous of my daughters Tonya and Joanna to arrange a helicopter flight over Sandbanks in 2013, as a Father's Day present; this is much appreciated and it yielded very good photographs.

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References and Select Bibliography

See also Bibliography of the Geology of Hengistbury Head webpage.

See also Bibliography of the Geology of Barton-on-Sea and Highcliffe.

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Bird and Ranwell (1964). ---


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Bray , M.J. and Carter, D.J. 1996. Poole Bay and Hengistbury Head. In: Allison, R. (ed) Landforms of East Dorset. Geologists' Association Guide, Geologists' Association, London.
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Bristow , C.R. and Freshney, E.C. 1986. Geology of the Poole - Bournemouth Area. Geological Report for DOE: Land Use Planning. British Geological Survey, Exeter.

Bristow, C.R., Freshney, E.C. and Penn, I.E. 1991. Geology of the Country Around Bournemouth. Memoir for 1:50,000 geological sheet 329 (England and Wales). London, Her Majesty's Stationery Office. 116 pp. ISBN 0-11-884377-X. British Geological Survey. Natural Environment Research Council. (This is the key modern publication to the geology of the Bournemouth area. It is a large paperback, probably still in print and originally sold at £24.75p. It is likely to be available in good local libraries. It is intended for use with the Geological Survey map 329. The emphasis of the publication is on outcrops, lithology and sediments with palaeontological topics covered briefly. It is useful in containing a bibliography of more than 100 references, many of which are not repeated here.)


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British Geological Survey Bristow , C.R. and Freshney, E.C. 1986. Geology of the Poole - Bournemouth Area. Geological Report for DOE: Land Use Planning. British Geological Survey, Exeter.

British Geological Survey. (the main BGS Memoir). Bristow, C.R., Freshney, E.C. and Penn, I.E. 1991. Geology of the Country Around Bournemouth. Memoir for 1:50,000 geological sheet 329 (England and Wales). London, Her Majesty's Stationery Office. 116 pp. ISBN 0-11-884377-X. British Geological Survey. Natural Environment Research Council. (This is the key modern publication to the geology of the Bournemouth area. It is a large paperback, probably still in print and originally sold at £24.75p. It is likely to be available in good local libraries. It is intended for use with the Geological Survey map 329. The emphasis of the publication is on outcrops, lithology and sediments with palaeontological topics covered briefly. It is useful in containing a bibliography of more than 100 references, many of which are not repeated here.)
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Bury , H. 1916. The physical geography of Bournemouth. Geological Magazine, 53, 133-134. By Henry Bury.
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The Channel Coastal Observatory , National Oceanography Centre, southampton

Large-scale, vertical, aerial photographs of the Wessex Coast are available free for downloading to persons who register with this organisation. You will require ER viewer software (available free on the internet) to see the pictures which are in ECW format, but they can afterwards be converted to other formats, as in the simplified JPG example of Sandbanks shown above (even if you click on the picture and zoom up this is still not at full resolution - see the original for details!). They are excellent images and well-worth examining. This is a highly recommended website! The following notes are from the Channel Coastal Observatory website.
"Welcome to the website of the South-East strategic regional coastal monitoring programme. The Channel Coastal Observatory is the data management and regional coordination centre for the Southeast Regional Coastal Monitoring Programme. The programme provides a consistent regional approach to coastal process monitoring, providing information for development of strategic shoreline management plans, coastal defence strategies and operational management of coastal protection and flood defence. The programme is managed on behalf of the Coastal Groups of the Southeast of England and is funded by DEFRA, in partnership with local Authorities of the southeast of England and the Environment Agency. The Channel Coastal Observatory is hosted by New Forest District Council, in partnership with the University of southampton and the National Oceanography Centre, southampton."
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Churchill , D.M. 1965. The displacement of deposits formed at sea level 6500 years ago in southern Britain. Quaternaria, 7, 239-249. Introduction: Submerged forests on the present coast of Britain, probably attracted interest long before Pepys drew attention to the presence of hazel fruits in peat exposed in the dock excavation at Tilbury, some 300 years ago. One coastal peat bed that is known to have formed in situ, is recorded at 60 to 65 feet below O. D. (Godwin and Willis, 1964) from \Port Talbot in Southern Wales. The bottom of the peat there has been dated at 10,000 B. C. A deeper but undated bed is the peat revealed by recent borings on the seaward side of the Chesil Beach near Weymouth, where it was found 83 to 85 feet below O. D., and in Holland, Jelgersma (1961) recorded five centimetres of peat 75 feet below sea-level that was radiocarbon dated to circa 7,700 B. C. Overlying these and younger peat deposits that have developed in situ there are estuarine and marine clays,. silts and sands, as well as other peat beds that alternate with these, as at Fawley near southampton and at Tilbury. The occurrence of such deposits has been recognised by Reid 1913, Wright 1937, and Godwin 1943, as the product of rising sea-level, downwarping or both of these processes at work since the time when the deposits were formed.
    The extent to which the relative shift of land- and sea-level is indicated by the presence of coastal peat deposits, requires the careful consideration of the relationship of the peat bed to its contemporary sea-level. Godwin (1943) has stressed the need for caution in relating a sequence of peat overlain by marine clay, to a changing in sea-level. Such peat beds may accumulate close to the mid-tide level behind barriers such as shingle spits and sand dunes, which can break down, expose the peats to the full tidal range and bury them under marine sediments without any change in level. Such a sequence as this however is characterized by sharp lithological boundaries and an absence of gradual succession by plants and animals. When a demonstrable sere that extends gradually, without interruption, from marine sands or clays with shallow water molluscs, foraminifera and diatoms, through saltmarsh clays with saltmarsh plants such as Suaeda maritima and molluscs such as Hydrobia or Scrobicularia, into brackish-water peaty clays with such plants as Cladium and Phragmites, and thence into eutrophic fen peats, fen carr or fen wood, there is some justification to suppose that the lowermost peat facies could have grown at a level somewhere in the tidal range, and thus be related to sea-level.
    For the present purpose of measuring subsequent changes in level, the lowermost datable peat from such a continuous succession of marine to freshwater deposits, provides the closest practicable index to sea-level. At the same time such facies may have formed at any level between that of mid- and high-tide. At only two sites (Burnham and lmmingham) have the peats used in this study not been shown to be part of a continuous halosere, and only because they are thin beds containing high frequencies of Chenopodiaceae pollen and found alternating with estuarine clays, is there any reason for including in them here.
    The extent to which the level of the deposits may be altered during their post-depositional history by loss of water or compaction of the underlying sediments by thick overburden, can result in peats in a maximal compression ranging between 80 to 90% of the original thickness (Jelgersma, 1961), and in sands as little as 2% (Athy, 1930). Clearly the horizons least susceptible to changes in level due to the progressive accumulation of overburden, are those organic horizons in contact with the underlying mineral substratum. Those most susceptible to changes of level are those organic horizons in contact with overlying mineral deposits as well as those. deposits that overlie deeper peat beds. Among the sites studied here, it is only at Tilbury and Alphen that the peats concerned are not those from the lowermost contact with the mineral substratum, and therefore liable to some downward compression.
    Another error of consequence in the present context is the time lag from when mineral sedimentation ceases to when the sedge fen or fen carr stage of the succession is reached. Only contiguous sampling for radiocarbon assay can give a precise indication of the time taken for colonisation at each site. However after radiocarbon dating the saltmarsh sequence described by Swinnerton (1931) from Chapel Point on the Lincolnshire coast, it was found that the entire sequence from the top of the lower peat through the phase of salt marsh clay accumulation and thence to Phragmites peat accumulation, followed by a reversion. to estuarine clay deposition, took only 700 years (Wright and Churchill, 1965). At Ynyslas the brackish water Phragmites peat immediately overlying the brackish water clays has not been dated but the radiocarbon age of the birch and brushwood peat, a rather late stage of the succession, gave an age 500 years younger than that expected for the Phragmites peat, whihc is believed to have formed at circa 6,500 B.P. [End of "Introduction". Continues with "Sites"]
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Claudio-Sales , V., Wang, P. and Horwitz, M.H. 2008. Factors controlling the survival of coastal dunes during multiple hurricane impacts in 2004 and 2005: Santa Rosa barrier island, Florida. Geomorphology, Vol. 95, Issues 3-4. Elsevier, pp. 295-315. By Vanda Claudino-Sales, 1, , Ping Wang, , and Mark H. Horwitz. Available online.
Abstract:
Santa Rosa Island is an 85 km-long, wave-dominated low-lying barrier island situated along the northwestern Florida coast, facing the Gulf of Mexico. The entire island was severely impacted by Ivan, a strong category 3 hurricane that made landfall about 45 km to the west in September of 2004. Ten months later in July of 2005, Dennis, another category 3 hurricane, made landfall about 30 km east of the western tip of the island. Santa Rosa Island is characterized by well-developed but relatively low dunefields, described in this paper as incipient and established dunes, based on the presence of grassy and woody types of vegetation, respectively. The dunes were severely eroded by the two hurricanes. This paper investigates the factors controlling the regional-scale destruction and survival of the dunefields.
Dune survival is controlled by: 1) hurricane characteristics, including intensity, duration, and frequency, and 2) morphological parameters including width of the barrier island, height and width of the dunefields, vegetation type, distance of the dunes to the ocean, and continuity of the dunefields. Three processes of dune destruction are described including, from most to least severe, inundation, overwash, and scarping. The interaction of all the above factors determines the different dune responses to the storm impacts. In general, the extensive and densely woody vegetated dunefields near the bay-side shoreline survived the storms, while the discontinuous dunes with grassy vegetation near the Gulf shoreline were almost completely destroyed.
[This paper discusses hurricane effects on a Florida barrier island. The island is of very large size but the western end is a relatively small spit resembling the Sandbanks Peninsula. The paper may be of use in considering the possible effects of a hurricane on the Sandbanks or Studland peninsulas. IMW] BR> .
Cooper , N.J. and Harlow, D.A. 1998. Beach replenishment: implications for sources and longevity from the results of the Bournemouth schemes. Pp. 162-177 in: Hooke, J. 1998. Coastal Defence and Earth Science Conservation. The Geological Society of London, Burlington House, London. 270 pp. ISBN 1-897799-96-9. Abstract: Beach replenishment is an effective shoreline management tool which can restore immediately coast protection and amenity functions of a beach... Issues concerning sediment sources and replenishment schemes longevity need to be addressed as future scheme use proliferates... From analysis of a long-term beach monitoring record in Poole Bay, southern England, it is suggested that a viable trade-off can be made between tight particle size grading control and the presence of retention structures in the design of effective replenishment schemes... The conservation of sediment resources is essential if replenishment is to be a sustainable option in the longer term.
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Devoy , R.J.N.1972. Environmental changes in the Solent area during the Flandrian Era. Unpublished dissertation for the B.A. Honours Degree in Geography. University of Durham, 47pp.

Devoy, R.J.N. 1982. Analysis of the geological evidence for Holocene sea-level movements in Southeast England. Proceedings of the Geologists' Association , vol. 93, part 1, pp. 65-90.
Abstract: Sea-level indicators in the form of shells, geosols, over-consolidated horizons and biogenic material interleaved in marine sediments, provide evidence of relative sea-level movements. Data collected largely from studies undertaken since 1950, show the sea surface rising from below -30 m O.D. at c. 9300 BP to above +0.5 m O.D. by c. 1700 BP. Details of individual studies are discussed on an areal basis. Ninety four indicator points dated either by radiocarbon or relative pollen techniques have been established and plotted on a time-depth graph. Of these, 55 were taken as providing reliable 14C and height evidence for the movement of MHWST. Statistical analysis of this data, using multiple regression and series of events techniques, suggests that a smoothly rising, exponential form of sea level rise does not form the best solution to the data and that alterations in the speed and direction of recovery may have occurred. A non-random environmental process may have been of primary importance in influencing the development and timing of sea-level indicators. Evidence is presented for the influences of climatic change and man in inducing coastal flooding after c. 3000 BP.
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Gao , S. and Collins, M.B. 1994. Beach Profile Changes and Offshore Sediment Transport Patterns Along the SCOPAC Coast: Phase 1 Technical Report. Report No. SUDO/TEC/94/95/C. Department of Oceanography, University of southampton.
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Godwin , H. and Godwin, M.E. 1940. Submerged peat at southampton: Data for the Sudy of Post-Glacial History. The New Phytologist, vol. 39, pp. 303-307, Cambridge, at the University Press. [On the section at southampton Western Docks].

Godwin, G., Suggate, R.P. and Willis, E.G. 1958. Radiocarbon dating of the eustatic rise in ocean level. Nature, London, 181, 1518-1519. [brief information on the Lower Hamworthy, Poole, borehole].

Godwin, G., Walker D. and Willis, E.H. 1957. [Title - ?]. Proceedings of the Royal Society, Series B, 147, pp 352-.

Godwin, G. and Willis, E.H. 1959. ---- [re the Lower Hamworthy Borehole].
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Halcrow , Sir William and Partners, 1980. Poole and Christchurch Bays Research Project, Phase One Report, 2 Volumes. Report to the Department of the Environment. Go to:
Halcrow .
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Hinchcliffe , J. & Hinchcliffe, V. 1984. Dive Dorset. Underwater World Publications, Area 4 - Offshore Diving, p. 164-5 (extract seen which starts at earlier page unknown and finishes at a later page). Supposed "fossil trees" at Middle Poole Patch, Bournemouth Rocks and Durley Rocks. A Tertiary age is implied. The "trunks" stand up to 5 feet high above the sea-floor. These have subsequently been examined petrographically, by XRD and SEM (by a student of mine) and are, in fact, pipes of pyrite with central cavities. Comparison has been made with the limonitic pipes of Redend Point, Studland, which might have been oxidised pyrite pipes of similar character.
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Hodson , F. and West, I.M. 1972. The Holocene deposits of Fawley, Hampshire and the development of southampton Water. Proceedings of the Geologists' Association, London, 83, 421-444. Abstract: Holocene estuarine deposits up to 21 m. in thickness, which were encountered in boreholes and excavations at Fawley, partly fill the southwestern side of the drowned valley of southampton Water. Saltmarsh clays with peat lie above and below tidal-flat clays of Atlantic age. The mollusc, foraminifera and ostracod faunas and the coccolith and diatom floras of these Holocene deposits are discusssed. Gravels of Calshot Spit are interbedded with these sediments to a depth which suggests the existence of the spit in Atlantic times or earlier. The spit has deflected the deep channel eastwards and has protected the south-western borders of the estuary from erosion... In the northern part of southampton Water, late Holocene estuarine beds transgress northward over Holocene freshwater sediments. Much of the thick estuarine sequence at Fawley corresponds in age to a thin freshwater succession in the north.
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Intergovernmental Panel on Climate Change (IPCC) . 2007. Climate Change 2007: The Physical Science Basis. Summary for Policymakers, 21pp. Contribution of Working Group 1 to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. This Summary for Policymakers was formally approved at the 10 Session of Working Group 1 of IPCC, Paris, February 2007. [Available online on the Internet.]
"Introduction:
The Working Group I contribution to the IPCC Fourth Assessment Report describes progress in understanding of the human and natural drivers of climate change, observed climate change, climate processes and attribution, and estimates of projected future climate change. It builds upon past IPCC assessments and incorporates new findings from the past six years of research. Scientific progress since the TAR is based upon large amounts of new and more comprehensive data, more sophisticated analyses of data, improvements in understanding of processes and their simulation in models, and more extensive exploration of uncertainty ranges...
Human And Natural Drivers Of Climate Change:
Changes in the atmospheric abundance of greenhouse gases and aerosols, in solar radiation and in land surface properties alter the energy balance of the climate system. These changes are expressed in terms of radiative forcing, which is used to compare how a range of human and natural factors drive warming or cooling influences on global climate. Since the Third Assessment Report (TAR), new observations and related modelling of greenhouse gases, solar activity, land surface properties and some aspects of aerosols have led to improvements in the quantitative estimates of radiative forcing...." [continues]

Future sea level rise estimates for the Wessex coast
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King , M.P. 1974. Beneath Your Feet: The Geology and Scenery of Bournemouth. The Purbeck Press, Swanage. 36pp, paperback booklet. By Michael P. King, B.A., County Borough of Bournemouth Education Committee.
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May , V. 1990. Replenishment of the resort beaches at Bournemouth and Christchurch, England. Journal of Coastal Research, SI (6), 11-15.
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Melville , R.V. and Freshney, E.C. 1982. British Regional Geology: the Hampshire Basin. Institute of Geological Sciences, H.M.S.O., London. (Good introduction to the geology of the region).

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Nowell , D. 2008. Coastal land is only leased from the sea. Letter and emails to the Editor, Guardian Newspaper, Monday, April 21, 2008, p. 33.
When it comes to coastal erosion (Waves of destruction, G2, April 17), unlike most other European countries we don't have a solidarity fund to compensate people for such natural disasters, and so the last owner is expected to pay when their house is demolished.
To stop a perverse game of beggar-my-neighbour where the unscrupulous try to sell to unsuspecting buyers, we should be leasing such coastal properties from the sea. Any land that is likely to disappear within a century would in effect become leasehold and the time left stated on the title deeds. In addition to a solidarity fund, limited compensation could be paid if such estimates proved to be wrong. The British Geological Survey, which already undertakes coastal surveys, could provide fairly reliable estimates revised every decade for places with cliffs like Happisburgh. This would be rather more problematic further south along the Norfolk coast since a major breach to this narrow barrier could happen any time this century.
Once breached, the northern Norfolk broads and several villages would be lost, and so a proper cost/benefit analysis is urgently required. Coastal defences would interfere with the movement of sediment down the east coast of England and have to be balanced against any likely impacts further down the coast.
David Nowell, Fellow, Geological Society

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SCOPAC - Sediment Transport. SCOPAC - Standing Conference on Problems Associated with the Coastline. There are many sections in this important publication. There is a an index map at: Sediment Transport Study - map showing areas.

More specifically for Poole Bay, Bournemouth and Sandbanks visit the map with detailed sediment transport information at:

Poole Harbour Entrance to Hengistbury Head">


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Shoreline Management Plan. 200? Poole and Christchurch Bays. Shoreline Management Plan - SMP - Key Publications

See these important documents on the plans for the coastal management or shoreline management of the area. Summarised contents of a version are given below and look for the section of interest. However, this SMP is not the final version, and there will be an update. If you do not find it directly from the links here, search by Google etc for the latest version, using the keywords - "Poole Christchurch SMP".

Poole and Christchurch Bays Coastal Management Group. 2010. (SMP - Shoreline Management Plan)
Poole and Christchurch Bays Coastal Management Plan (or SMP - Shoreline Management Plan). Draft SMP2. Draft version of the SMP, later to be replaced by final version (see this when it is available. SMP2 is due to be published in April 2010.). Available online as PDFs at Poole and Christchurch Bays Coastal Management Plan.

Contents: Draft SMP2
Section 1, Introduction
Section 2, Environmental Assessment
Section 3, Basis for Development of the Plan
Section 4, Appraisal of Options and Rationale for Preferred Plan:
Section 4.1, Introduction.
Section 4.2, Policy Development Zone 1 Central and Eastern Sections of Christchurch Bay (Hurst Spit to Friars Cliff).
Section 4.3, Policy Development Zone 2 Christchurch Harbour and Central Poole Bay (Friars Cliff to Flag Head Chine).
Section 4.4, Policy Development Zone 3 Poole Harbour and Associated Coastline (Flag Head Chine to Handfast Point, including Poole Harbour).
Section 4.5, Policy Development Zone 4 Swanage (Handfast Point to Durlston Head).
Section 5, Summary of Preferred Plan and Implications
Section 6, Policy Summary, including Policy Summary Map.
Appendices (all documents open in a new window)
Appendix A, SMP Development.
Appendix B, Stakeholder Engagement.
Appendix C, Baseline Process Understanding, including Coastal Process Report and Flood and Erosion Mapping. Accessible from a separate page including No Active Intervention (NAI) and With Present Management (WPM) assessments, and summaries of the data used in assessments.
Appendix D, Natural and Built Environment Baseline (Thematic Review).
Appendix E, Issues and Objective Evaluation.
Appendix F, Strategic Environmental Assessment.
Appendix G, Scenario Testing.
Appendix H, Economic Appraisal.
Appendix I, Estuary Assessment.
Appendix J, Habitat Regulation Assessment - Appropriate Assessment.
Appendix K, The Metadatabase, GIS and Bibliographic Database is provided to the operating authorities on CD. It will be included in the final SMP.
Appendix L, Water Framework Directive (WFD)
Appendix M, Review of Coastal Processes and Associated Risks at Hengistbury Head.

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Reid , C. 1898. Geology of the Country round Bournemouth. Memoir of the Geological Survey. Sheet 329 (England and Wales). By Clement Reid.

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Velegrakis , A.F. 1994. Aspects of the Morphology and Sedimentology of a Transgressional Embayment System: Poole and Christchurch Bays, Southern England. Unpublished Ph.D. Thesis, Department of Oceanography, southampton University, 319pp.

Velegrakis, A.F., Dix, J.K. and Collins, M.B. 1999. Late Quaternary evolution of the upper reaches of the Solent River, southern England, based on marine geophysical evidence. Journal of the Geological Society, London, vol. 156, pp. 73-87. Authors' address: School of Ocean and Earth Science, University of southampton, National Oceanography Centre, southampton (then southampton Oceanography Centre), European Way, southampton, SO14 3ZH, UK. [This is a key paper with a map showing the offshore buried channels in Poole Bay and Christchurch Bay.]
Abstract: Geological evidence suggests that during the Late Quaternary, a river system (the Solent River) drained a large part of central Southern England. Its upper reaches flowed in a west-east direction, flanked to the south by a Chalk ridge (the Purbeck-Isle of Wight Chalk Ridge). Today, only part of the upper reaches of the river's tributary channels remain, as the area was inundated during the Flandrian Transgression, forming. an embayment system (Poole and Christchurch Bays). In order to map the offshore buried channels of the upper reaches of the Solent River an extensive set of shallow-marine geophysical data was analysed and interpreted. The results of this investigation show that the Solent River system was disrupted irreversibly by southerly capture of its upstream section before the Flandrian Transgression. This disruption was the result of the fluvial breaching of the southern barrier of the system (the Purbeck-Isle of Wight Ridge) at three points, probably during Late Devensian time. Poole Bay was first to be submerged during the transgression. The estuaries which resulted from the drowning of the fluvial palaeovalleys of Poole Bay were infilled with transgressive facies sequences which have been preserved within the buried palaeovalleys. In contrast, Christchurch Bay was submerged at a later time, but because of the abrupt manner of its inundation, no transgressive facies have been preserved within its buried palaeovalleys. [end of abstract]
[Example extract from the introduction] The Isle of Wight, southern England, is separated from the mainland by a stretch of water known as the Solent (Fig. I). The Solent is located at the southern margin of the Hampshire Basin, an elongated asymmetrical downwarp of Tertiary deposits, the southern limb of which exhibits a near-vertical northern dip, whilst the beds on its northern limb slope gently southward (Melville & Freshney 1982). It has been widely proposeq that, during Pleistocene lowstands, the Solent formed a segment of a major axial stream (the 'Solent River'), which integrated all the consequent rivers of the basin (Fox 1862; Reid 1905; Everard 1954; West 1980). It has been suggested that this river constituted one of the principal northern tributaries of the English Channel River, a major river system established over northwestern Europe early in the Middle Pleistocene Epoch (Gibbard 1988). The Solent River flowed along a large W-E-trending valley incised into Tertiary arenaceous and argillaceous sediments and surrounded by high Chalk country (the Wiltshire and North Dorset Downs to the north and the South Dorset Downs and the Purbeck-Wight Chalk Ridge to the south). Much of the catchment area of the river was drowned during the last eustatic sea-level rise. Only parts of the tributary river systems are still intact; these form the modern drainage network of the area (Fig. 2).
Evidence for the existence of the Solent River system is distributed throughout the area. Onshore, extensive deposits of Pleistocene sands and gravels occur, forming terraces along the present river valleys (Keen 1980; Freshney et al. 1985; Allen & Gibbard 1993), and underlying the Flandrian deposits of some of the estuaries of the area (Nicholls 1987). Offshore, marine geophysical surveys have revealed systems of buried river valleys under the present seafloor, incised to a maximum depth of 46 m below OD to the east of the Isle of Wight (Hamblin et al. 1992). [continues for more than 14 pages, with maps and diagrams].

Velegrakis, A.F., Dix, J.K. and Collins, M.B. 2000. Late Pleistocene - Holocene evolution of the upstream section of the Solent River, Southern England. Pp. 97-99 in: Collins, M. and Ansell, K. 2000. Solent Science - A Review. Elsevier, Amsterdam, 385pp. [Using shallow seismic and echo-sounder profiles, seven palaeovalleys have been recognised offshore in Poole and Christchurch Bays. In Poole Bay, Palaeovalleys I, II and III appear to cut southward through the Purbeck-Wight ridge. In contrast Palaeovalleys IV, V, VI and VII in Christchurch Bay do not appear to cut through the Ridge. Valley-filling sediment of significant thickness are found only within Palaeovalleys I and II (Incidently Palaeovalley I has been intersected by a civil engineering borehole on the Sandbanks Peninsula)]
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West , G.H. 1886a. in: Report of the committee ... appointed for the purpose of inquiring into the rate of erosion of the sea coasts of England and Wales, and the influence of the artificial abstraction of shingle or other material in that action. 6 Christchurch to Poole. Topley, W. (editor). Report of the British Association for the Advancement of Science for 1885, 427-428.

West, G.H. 1886b. The geology of Bournemouth. Proceedings of the Dorset Natural History and Archaeological Society, 7, pp ?.
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White , H.J.O. 1917. Geology of the Country around Bournemouth: Explanation of Sheet 329 [Geological Survey 1 inch to one mile sheet for Bournemouth]. 2nd Edition. Memoirs of the Geological Survey, England and Wales. Published by order of the Lords Commissioners of His Majesty's Treasury. Printed by J. Truscott and Son, Ltd, under the authority of His Majesty's Stationery Office. 79 pp. [This is an old edition of the Geological Survey Memoir - see also - Bristow, C.R., Freshney, E.C. and Penn, I.E. 1991. Geology of the Country around Bournemouth. Memoir for 1:50,000 geological sheet 329 (England and Wales). British Geological Survey, London, 116p. There is also the first edition of 1898 by C. Reid. Prefacxe to the Second Edition by A. Strahan, Director: "The first edition of this Memoir, which was written by the late Mr. Clement Reid, was exceptionally brief, a general memoir descriptive of the Hampshire Basin as a whole having been at that time in contemplation. Circumstances have prevented the preparation of the larger work, and opportunity has now been taken ot the exhaustion of the stock of the original pamphlet to produce a memoir on the lines of other New Series Sheet Explanations... continues .. Much of the ground has been re-examined by Mr. White in order to bring the memoir up to date, but the map remains unaltered as the edition published in 1895 and colour-printed (Drift) in 1904."]

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Appendix - Questions for Students



Question SB1 (historical geology - Quaternary) In which stage of the Pleistocene did the cutting of the deep river channel most probably occur? (hint - it was quite late!). Suggest a date BP (before the present) to the nearest 2ka (2000 years) for the flooding of channel during the Flandrian (hint - not at the beginning of the Flandrian Transgression because the channel floor is too high). How long ago did Poole Harbour acquire most of its present form?


Question SB2 (general knowledge). Why is there a relative deficiency of seaweed on the beach here and do you expect this condition to change? Explain.

Question SB3 (sedimentology or general knowledge). Why are pebbles generally rare at Sandbanks and not in sufficient quantity to form beach cusps, as at more eastern parts of the Poole Bay coast? Why are the few pebbles present only seen in the intertidal zone?

Question SB4 (clastic sedimentology). Although no scale is given, you can estimate in your head (assuming the shells to be about 2 cm) a rough particle-size histogram of the sediment shown on the photograph above. Would the pebble mode or the medium-sand mode have the highest peak in terms of weight? Do you expect much material at high phi numbers to be present and explain why you state this? (Tip - the phi-scale is a widely-used, logarithmic scale for particle sizes and it is convenient to keep a chart for coversion from millimetres. A logarithmic scale is employed because otherwise comparison of sand grains and boulders would have been difficult. A negative log scale is used to avoid having some common sand sizes appearing as negative exponents. The base 2 rather than the base 10 avoids awkward fractions when converting from an arithmetic scheme. Although in theory phi is dimensionless, we can in practice use the simple expression that : phi = -log2 mm. Thus boulders are at negative phi numbers and clay is at high positive phi numbers. See a standard sedimentology textbook for more information. )

Question SB5 (palaeoenvironmental sedimentology). If a leached ancient deposit was found with the characteristics of this sediment why might the subangularity of both sand grains and pebbles lead to a false palaeoenvironmental interpretation?

Question SB6 (geomorphology - general). In terms of source of sand and longshore drift compare and contrast the sand spits of Sandbanks and Weymouth. Name a third sand spit in the region which has similar features.



Notice that the land surface in the narrow part of the Sandbanks peninsula is low and in some cases only a few metres above high-tide level (former sand-dunes have raised the level in much of the southern part). The sea-front part of Weymouth is situated on a very similar sand-spit to that of Sandbanks and it is also generally sheltered from southwesterly storm waves. However, the streets on the Weymouth sand spit were flooded at the Narrows and adjacent area in the storms of 1802 and 1824, at a time when Sandbanks was not developed (see illustrations in Burnett, 1982) . Sandbanks sand spit might be slightly more sheltered than Weymouth sand spit in terms of storm action in relation to fetch. Both are quite open to southeasterly storms though (examine a map of the English Channel).

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Copyright © 2013 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 or for any commercial activity. A reasonable number of images and some text may be used for non-commercial academic purposes, including field trip handouts, lectures, student projects, dissertations etc, providing source is acknowledged.

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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.

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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.