West, Ian M. 2013. White Nothe to Bat's Head, west of Durdle Door, Lulworth, Dorset; Geology of the Wessex Coast. By Ian West, Romsey, Hampshire and Southampton University. Internet site: www.southampton.ac.uk/~imw/White-Nothe-Bats-Head.htm. Version: 20th December, 2013.
White Nothe to Bat's Head, west of Durdle Door, Lulworth, Dorset, Geological Field Guide

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.

See also: Ringstead to White Nothe

|Home and Contents |Lulworth Cove |Fossil Forest |Dungy Head & St. Oswald's Bay | |Durdle Door, near Lulworth Cove, Dorset| Lulworth Geological Bibliography

Click here for the full LIST OF WEBPAGES


See also the related:

Ringstead to White Nothe webpage.


(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.)

View of the Chalk cliffs of the Dorset coast from White Nothe to Bat's Head and Swyre Head, as seen from Weymouth, Dorset, with zoom lens, 24th March 2009

Ascending Smugglers Path, White Nothe, Dorset, the old escape route in Moonfleet

General view eastward to Bat's Head and Durdle Door, from the upper Chalk cliffs of White Nothe, Dorset, 2006

View of the Chalk cliffs of the Dorset coast from White Nothe to Bat's Head and Swyre Head, as seen from the upper slopes of White Nothe cliffs, old photograph of Ian West


Chalk cliffs between White Nothe and Bat's Head, Dorset, including the inaccessible bay, 26th May 2013


View towards White Nothe, from Swyre Head, near Durdle Door, Lulworth, Dorset, 14th November 2012

Go back to top


This is in part a continuation to the west of the coast described in the
Durdle Door webpage, which should be consulted.

See also the:
Ringstead to White Nothe webpage, White Nothe and the coast westward to Ringstead.

Go back to top


Bat's Head - Introduction

The Upper Chalk promontory of Bat's Head seen from the east, Dorset coast, west of Durdle Door, March 2009

The Bats Head promontory and natural arch in Lewes Nodular Chalk, west of Durdle Door, near Lulworth Cove, Dorset, March 2011

Go back to top

Bat's Head - Stratigraphy and Structure

The Bats Head promontory and natural arch in Lewes Nodular Chalk, west of Durdle Door, near Lulworth Cove, Dorset, March 2011

Bat's Head west of Durdle Door, near Lulworth Cove, Dorset, with conspicuous south-dipping shear planes, 23rd March 2012

Bat's Head and Butter Rock, west of Durdle Door, near Lulworth Cove, Dorset, 23rd March 2012

Bat's Head, west of Durdle Door, near Lulworth Cove, Dorset, 14th November 2012

Cliffs towards Bat's Head, from Durdle Door

Bat's Head - details

Bat's Head, close view

The beach ends at Bat's Head. Here, the Chalk is vertical. It belongs to the planus Zone, named after the echinoid (sea-urchin) Holaster planus. This is Turonian in terms of Stages, but has been classified as part of the Upper Chalk because it contains flints. This part of the Chalk is referred to on the new Geological Survey Sheet 342 for Swanage as Lewes Nodular Chalk Formation, and referred to as "Chalk, white, flinty, hard and nodular". It is part of the "White Chalk Subgroup" of the "Chalk Group".

A notable feature here are the small thrusts, part of the pattern of conjugate shears, are clearly visible (and also figured by Bevan, 1985, fig. 2, p. 40). One photograph, the left one, shows the general view of Bat's Head from near Durdle Door; the middele one shows details with contrast enhanced, and the third, to the right, has been taken close to the headland. The projecting cliff shown projects approximately north-south, with north on the right-hand side. extendThe displacement on the faults can be seen to be small, and there is also some north-dipping shearing. Notice how the overturning increases northward in the lower part of the cliff. Visible to a limited extent on the right of the left-hand photograph, at the seaward ends of two valleys there is some south-dipping debris of chalk, with depositional dips. This has moved downslope by solifluction during periglacial conditions of the late Pleistocene.

Bats Head, Butter Rock and a dry valley in Chalk

For further study, here is an additional photograph of Bats Head and Butter Rock, taken in this case from the land, from the slopes of Swyre Head in the east. Notice that Butter Rock is lined up with a Chalk Valley, that is now dry with any water running underground through the permeable Chalk. There are low reefs of Chalk in the water south (seaward) of the stack. Observe also that the strike of the vertical or slightly overturned Chalk is visible in the reefs on the shore.

Go back to top

Bat's Head Geomorphology - the Intertidal Notch

Notch at Bats Head

Notice the erosion at the foot of the Chalk cliffs with a notch developed. The cave through the headland is Bat's Hole or Bat's Eye and eventually the end of the headland will be separated as a sea stack (Canning and Maxted). It is interesting to note that apart from the obvious green notch there is another recess or small cave, showing some evidence of collapse. This is adjacent to the higher part of the beach. There is a similar recess on the other side of the headland, and another cave may link through here in due course. This upper and landward recess is presumably due to occasional high and breaking waves causing abrasion with pebbles and sand.

The Intertidal Notch is more extensively developed. This is the lower green notch in the photographs. This is presumably formed largely by the usual pattern of waves, again using sand as an abrasive. Its origin is not simple, however and some biological action may also be involved. It is considered in more detail below.

Intertidal notches in cliffs have been discussed by Sunamura (1992). He mentioned that a clear indicator of cliff erosion is the presence of a notch, a laterally extending hollow at the base of a cliff, its width being greater than its depth. A shallow notch is sometimes called a nip (Higgins, 1992). A notch roof which is nearly horizontal is termed a visor Wentworth (1939), and is a common feature on limestone coasts in tropical regions. A visor does not seem to be well-developed at Bats Head.

As Sunamura (1992) pointed out it is common for beach material to cover the base of the cliff, and here there is probably sand under the water. The deepest penetration of the notch is usually slightly above the cliff/beach junction. You can see that the deepest penetration is low both in the photographs of Bats Head and of Butter Rock. The rate of retreat at Bats Head has not been measured, but is likely to be in centimetres per annum rather than metres. Old photographs do not show drastic changes on this stretch of coast.

Studies of notches in other parts of the world have shown that the notch height, the vertical distance from the notch floor to the tip of the visor (or upper limit), increases with tidal range and with exposure to storm wave action. The tidal range is quite limited here at Bats Head but there is significant exposure to storm waves, even on the east side. The notch roof tends to be horizontal on sheltered coasts, but becomes inclined on more exposed sites. For references on these topics see Sunamura (1992). That author recommends that notch dimensions and configurations should be related to quantified wave intensity and rock strengths.

Belov, Davies and Williams (1999) have carried out mathematical modelling of cliff erosion with a notch at the base. They have developed an equation (the BDW Equation) for both steady state and time-dependent erosion. Their theory produces modelled cliff profiles which requires the assumption that wave-erosion intensity decreases exponentially with height. The modelled profiles give smoother curves than is seen here. Examination of the photographs here suggests that at Bats Head there is a sharp cut-off of erosion near high-water level, rather than an exponential decrease up the cliff. Consider just why the pattern here does not match the smoother, exponential-type, BDW model. One possibility is that it is probably connected with transport of clasts during corrasion (abrasion). The decrease of wave action up the cliff may not be comparable to the decrease in clast transport up the cliffs by the waves. Just how high are the clasts (particularly the pebbles) normally transported up the cliffs for abrasive action?

The work of Sunamura (1992) sheds more light on the abrupt upper boundary of the notch. He pointed out that abrasive action is easily inferred from the fact that the surface of rocks in the vicinity of beaches with notches is smoothed and polished. At Bats Head the notch does not seem polished, but this may be the result of bioerosion (attack by organisms) as an additional factor, and this is of course the reason why the notch is green. Chalk in the area certainly does seem smooth. This is the case above the notch at Bats Head and on the platform of marine erosion at Swyre Head. Sunamura noted that the process of notch development associated with mechanical abrasion can be observed in a laboratory experiment. When waves rushing up the beach reach the cliff, they form a vertox with a horizontal axis and this vortex entraps beach sand. It scrapes the suspended beach sand against the cliff. This is the "Sand-armed Vortex Theory". Although it is not easy to demonstrate this process in the field it explains the relationship between the position of a notch and the elevation of the beach surface. The sand-armed vortex will only take place in the breaking waves close to the level of the sand beach and not extend far above it.

The comments given here are not the result of thorough study, and are only preliminary guidance intended to provoke consideration and discussion. The study of intertidal notches is a complex matter, and many references, not repeated here are given in Sunamura (1992). It is important to note that mechanical erosion or abrasion (corrasion) is only one of the processes which may be involved. Notch geometry is an integration of either of the following processes or a combination of them:

1. Mechanical erosion - abrasion.
2. Chemical erosion - solution.
3. Biological erosion (bioerosion) - boring or grazing by marine organisms.

The intertidal erosional notch in the Chalk here requires further study, and is a good topic for student studies. Algal and solution activities involved would be more difficult to study than some other aspects and may need a longer period of research, with thin-section work, SEM and geochemistry.

For comparison, look also for evidence of the notch in the cliffs of near-horizontal Chalk near Harry Rocks in the east of the Isle of Purbeck. Go to the Harry Rock webpage.


Lone Beach, or Inaccessible Beach, beyond Bat's Head

The beach beyond Bats Head is not usually accessible except by boat. I have mentioned it on diagrams as "inaccessible beach" but House terms it - "Lone Beach", which is a good name. This coastal stretch is of particular interest in showing the foresyncline in front of the Purbeck Monocline. You can get to the beach but it is not easy without a boat. I have swum round Bats Head wearing geology boots and carrying a geology hammer, but this is not now recommended now for safety reasons.

Go back to top

Chalk Cliffs Between Bat's Head and White Nothe

Go also to: Ringstead and White Nothe Geology.

Chalk cliffs west of Bats Head

Above is an old sketch of the Chalk cliffs from White Nothe, eastward to the Lulworth Area. The foresyncline of the major fold is in the cliffs of Inaccessible Bay, but the dip of the strata can be observed from the cliff top in reasonable safety at certain places. It is interesting to find this change of dip when walking from White Nothe to Durdle Door on the cliff-top footpath. The dry Chalk valleys or coombes, so strikingly truncated by the modern sea cliffs, were formed in the Pleistocene when the chalk hills were frozen with permafrost. During the spring and summer it was possible for water to flow on the surface and erode these valleys. Solifluction of the active zone in these periglacial conditions resulted in deposits of chalky head. Elephant remains are found in similar material on the Isle of Wight (at Freshwater Bay) and at Brighton (above the raised beach at Kemp Town). At Beer in Devon there are thousands of humanly-flaked flints and other artefacts in chalky head.

This Victorian "helicopter view" of Middle Bottom (SY 788807), on the left, to Bats Head and further east on the right is from Damon (1884). It shows the foresyncline west of the Bats Head. The Weymouth paddle steamer is presumably heading for Lulworth Cove. Compare with the photograph of Rowe, provided below.

Bay west of Bats Head

Old photograph of Lone Beach west of Bats Head as published by Rowe in 1902. The structure and Chalk zones are shown. Compare with image above of the cliffs between Middle Bottom and Bats Head. Note the south (seaward) dipping chalk on the left which is effectively north of the foresynclinal axis. When a suitable modern photograph is available comparison of the state of cliffs in 1002 can be made with the recent state of the cliffs here. The original photograph has been changed in respect of some minor tinting and the provision of new labels.

Paddle steamer at Lulworth Cove

This note follows from the view of the 1884 paddle steamer off Middle Bottom above. It was common for geologists to visit Lulworth Cove by paddle steamer. Dawson in 1882, probably arrived on the steamer shown in the old etching. He described the paddles slowing and the steamer entering the narrow slit in the rock and passing into the " cerulean waterpool " surrounded by the variegated hues of the Wealden and the Greensand. W.H.Huddleston led a " Marine Geological Excursion from Swanage to Weymouth " for the Dorset Natural History and Antiquarian Field Club with a party of 140 people in 1907 on the S.S. Empress. This ship (although I suppose that it might not have been the same Empress) was still taking geologists like me to the cove in 1955. Huddleston's party visited the fossil forest and discussed the silicified trees and the Broken Beds. " The Assistant Secretary ventured to ask Mr Hudleston how long he supposed it might be since these fossilised tree stumps had been living, verdant things in the vegetable world. The eminent geologist answered that in the domain of geology all computations of time are utterly empirical; but as the trees belonged to the Jurassic period, it would not be at all excessive to put it down as eight millions of years. ".

Paddle steamer backing out of Lulworth Cove

For paddle steamer enthusiasts here is the Empress backing out of the cove through the narrow entrance. The Empress with the Monarch, the Embassy, the Consul and the Emperor of India were all paddle steamers belonging to Cosens and Company of Weymouth. Most of these were kept at Poole and ran regular trips from Bournemouth Pier to Swanage Pier in the 1950s which provided a good opportunity to see Harry Rocks and the famous Ballard Down Fault. Sometimes they went on to Lulworth Cove or went to the cove from Weymouth. Nowadays only one sea-going paddle steamer remains and this is the Waverley which not from this area. It still occasionally visits Lulworth Cove.

Go back to top


Fountain Rock

The Fountain Rock, east of White Nothe, is something of a Dorset secret, but it shows good horizontal Chalk at about the axis of the foresyncline, old photograph by Edwin Kestin in Llewellyn Pridam's book - The Dorset Coastline

Go back to top

Map Errors of Bats Head and White Nothe area

The following British Geological Survey maps cover this area:

British Geological Survey. 1974. 1:50,000 geological map - Weymouth, Sheet 342. Old edition, based on a 1896 survey.

British Geological Survey. 2000. Geological Map: West Fleet and Weymouth. 1:50,000 Series, England and Wales Sheet 341 and part of sheet 342. Solid and Drift, with seafloor geology, cross-sections and other data. The British Geological Survey Maps are notable for their high quality and held in high regard. Unfortunately, as has been pointed out by House (2001) , this new relatively new map does not seem to show the geology correctly in the Bats Head to White Nothe area. The following comments explain the problems.

Bats Head and Offshore Rocks

The offshore rocks of Portland Stone (shown in the photograph) at Bats Head, the Cow and the Calf have been placed not in a Portland outcrop, as has been known since 1818, but in the Chalk Group. Previous British Geological Survey have always shown them correctly and the memoirs have commented on their correct composition (e.g. Strahan (1898)). This is obviously not a real geological error, but some problem of production or proof-reading of the final version of the map. There are some other strange aspects of the map. The well-known foresyncline of Chalk here is shown, mistakenly, with the symbols of an anticline and the Chalk outcrop is shown too wide. On the south side of the fold the Chalk is shown in apparently unconformable contact with the Portland and Purbeck strata. In fact, the "Late Kimmerian" unconformity here is the base of the Gault, not the Chalk. The Chalk could only be in contact with Purbeck by faulting, but a fault is not shown. Another British Geological Survey Map, the Offshore Geological Map - Portland, shows a more correct interpretation.

The British Geological Survey maps are normally very good. Obviously, certain geological boundaries are disputable or difficult to locate, but in general these maps are of excellent quality and value. It is well-worth purchasing them from the BGS website!

Go back to top

More on the Offshore Portland Stone Rocks

The positions of the offshore rocks in the Durdle Door and Bats Head area are shown in an aerial photograph and in views from the sea in the book of Bruce (1989). They are are also shown on the Ordnance Survey, 125,000 map - Purbeck and South Dorset, Outdoor Liesure Series No. 15. Bruce discussed the seafloor topography here. There is deep water inside the Durdle Door archway, although it is not clear as to why this should be. He also commented that the remains of the breached Portland Stone cliff extends as a three-quarter mile reef to the west and is a hazard to yachtsmen, requiring careful negotiation. The first part of the reef, only 6m west of Durdle Door is the Frenchman Rock; this is submerged and about 1m below the surface at low water. Bull Rock is south of Scratchy Bottom. The Blind Cow, often covered, is south of Swyre Head. Then at Bats Head comes the dominant rock, the Cow, a resting place for shags (or cormorants). West of this is the Calf, which like the Cow, has underwater extensions on both sides. The Portland Stone outcrop is clearly showing some swing southward at the Calf. The outcrop is well shown in Bruce's aerial photograph, plate 73, even though it is in monochrome.

Bats Head is shallow on either side and it is possible to walk through Bat's Hole at low tide. There is a mile of beach between Bat's Head and White Nothe called Middle Bottom. It has a steep shingle beach (Bruce, 1989).

Go back to top


White Nothe

White Nothe near Weymouth, Dorset, with a cloud plume, as seen from near Ringstead, September 2006

A view of White Nothe, a headland of south-dipping Chalk, as seen from Bran Point near Osmington Mills, Dorset, 2nd March 2009

White Nose, a Dorset headland, with the base of the Smugglers Path shown

A small landslide near the souhern end of White Nothe, Dorset, 26th May, 2013


See also the related:

Ringstead to White Nothe webpage.

Go back to top


I am very grateful for the continued support for the continuation of this website by the Dean and the Staff of the Faculty of Natural and Environmental Science, Southampton University. The hosting of the website is by Information Systems Services of Southampton University, to whom I am very grateful. I very much appreciate the kind help and cooperation of the Channel Coastal Observatory in making available excellent aerial photographs of the region of study. I thank the various geologists and students who have accompanied me on various field trips on this coast. My wife Cathy has very kindly provided background support for the production of this and all the other webpages. I thank Alan Holiday for kindly providing some photographs of White Nothe.

Go back to top

Durdle Door, from Dungy Head

Go back to top

|Home and List of Webpages

See also: Ringstead to White Nothe

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. No permission can be given for reproduction of any images of the Lulworth Cove area in books or in other websites, for special reasons.

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 guides on the Internet no person is advised here to undertake geological field work in any way that might involve them in unreasonable risk from cliffs, ledges, rocks, sea or other causes. Not all places need 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 cancell 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.

Go back to top

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.