Ian West,
Romsey, Hampshire
and Visiting Scientist at:
Faculty of Natural and Environmental Sciences,

Southampton University,
Webpage hosted by courtesy of iSolutions, Southampton University
Aerial photographs by courtesy of The Channel Coastal Observatory , National Oceanography Centre, Southampton.
Website archived at the British Library

Home and List of Webpages |Field Guide Maps and Introduction| Studland and South Haven Peninsula |Studland - Tertiary Cliffs and the Agglestone |Studland - Poole Harbour Side of Peninsula |Studland - Bibliography of Geology |Alum Bay and the Needles, Isle of Wight |Swanage Bay and Ballard Cliff| Durlston Bay and Peveril Point|

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[wide image below - comparison 2009-2015, click for large version]

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INTRODUCTION

Safety

It is emphasised that the Chalk cliffs in the Harry Rocks, Ballard Point area are vertical and potentially dangerous, and there have been some rare fatalities. Great care should be taken, especially in bad or windy weather. However, if correct safety procedures are taken the walk is very easy and safe, comfortable and suitable for ordinary walkers including older people. The real risk is associated with uncontrolled children, dogs and intentionally adventurous people who might purposely walk to dangerous cliff-edge locations. There may be some people who probably should not be near a vertical cliff edge. In general, though, the place is quite suitable, in normal weather conditions, for almost any adult, including old walkers or older geologists. Some people may wish to use a treking pole for additional stability. Photographers should not take intentional, cliff-edge risks to get good photographs.

Stay on the well-worn footpath and keep a reasonable distance from the cliff edge. If you have any problems with vertigo or any instability or risk of falling when walking, stay back at least two metres from the cliff edge. In any case do not go closer than one metre. Do not be tempted to show off by standing on the edge of a vertical cliff. This place can be more dangerous than most cliffs because the edges are abrupt and often at right-angles with risk of a direct fall to the sea or rocks. However, it can be visited in safety by staying on the standard and well-used footpaths, and using commonsense. The place is not necessarily safe for children or dogs, unless they are kept under very good control. (I have seen people successfully use marker ropes to keep school children a certain, safe distance from the cliff edge.)

A walk around Harry Rocks area, starting from Studland, is quite easy, even if continued up on to Ballard Down, because the slopes are gradual. Ascending from Swanage Bay involves a steep slope up more than 100 metres height in a short distance. If this is done, use only the footpaths and do not attempt to climb the hazardous Chalk cliffs of Ballard Cliff. Because a locality is described here there is no implication that it should be visited. Some parts are described from previous literature and are not, in fact, accessible to the writer without either a boat or with safety ropes. Only go where it is obviously safe to do so on the day.

With a low spring tide, accurate timing and a little wading it is possible to walk around the foot of the Chalk cliffs from Studland to Old Harry Rocks, and I have done this more than once. This shore walk on rock and seaweed is not recommended, though, and could lead to fatal accidents. Just as soon as the tide starts to rise it is essential to depart from Harry Rocks (you may have less than 15 minutes there - do not delay!) because the little paddle round the small headlands, approaching No Man's Land, can quickly turn into deep wading. You can very easily be cut off and there is no escape route to higher ground. Thus a walking visit on the shore is not easy and it is probably better to travel there by boat.

Regarding the wading hazard, see the following extract from the BBC website online (Dorset section) for 22nd March 2015.

"Four stranded teenagers rescued from Old Harry Rocks in Dorset.
The group had been on a walk to Old Harry Rocks on the Isle of Purbeck [presumbly along the shore at the foot of the cliffs, rather than the usual walk on the cliff top]. Four teenagers were "extremely fortunate" to be saved from rocks cut off by the sea after they were found with water rising up to their chests. The male foreign students were stranded at the Old Harry chalk stacks on the Isle of Purbeck, Dorset, after a rising tide cut them off on Saturday evening. Poole Lifeboat said the group were found "in the nick of time" just before 19:00 GMT. Other walkers have been warned to not to venture out on to the foreshore. Lifeboat volunteer Jonathan Clark said: We are experiencing very extreme spring tides and low waters at the moment due to the spring equinox and areas of the foreshore are being exposed. This weekend it has been the biggest one of the year and though areas may seem accessible, it is not a good idea. The people that we were tasked to today were extremely fortunate. If they had not been able to raise the alarm, then today would have been a totally different scenario"... continues.

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As at all localities, the extent and type of risk varies from day to day, and varies according to the people present. On-the-spot assessments and decisions are needed on the occasion of the visit.

Official boats trips to see the cliffs and rocks can be taken from Swanage or from Poole Quay (and possibly from Bournemouth), and there is normally no hazard in this. Small boat activities can be dangerous and not considered here.

INTRODUCTION:

Access

The easiest way to visit this area is to go to Studland village, follow the signs to the Bankes Arms pub in Manor Road, and adjacent to it there is a |National Trust car-park (pay and display). From here it is a pleasant cliff-top walk to Harry Rocks and on to Ballard Point, if required. As noted above, these cliffs can also be reached from Swanage by ascending Ballard Down.

Swanage and Studland are situated on the east coast of the Isle of Purbeck, a scenically attractive peninsula of Jurassic, Cretaceous and Tertiary strata. They are within easy reach of other famous localities such as Lulworth Cove and Kimmeridge Bay .

INTRODUCTION

Aerial Photographs - Introductory

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Aerial photographs show the spectacular topography of this beautiful stretch of high Chalk cliffs, with promontories, sea stacks and natural arches (more aerial photographs follow later in particular sections of the webpage). It can be viewed from the South West Coast Path on the cliff top, walking from Studland or Swanage, or by boat. A major and remarkable fault, the Ballard Down Fault, is in this stretch of cliffs. To the south of this at Ballard Point the Chalk is vertical. To the north it has a low dip and is almost horizontal. The structure has been discussed as a geological problem since Victorian times. The stretch of coast is very good for geomorphological studies, but care must be taken above these wild and vertical cliffs. You can see the Foreland, No Man's Land, Old Harry Rocks and the Pinnacles.

INTRODUCTION:

Geological Maps

The British Geological Survey map, 1:50,000, Solid and Drift, 2000 Edition, Swanage Sheet, 343 and part of 342, is well worth purchasing. It can be obtained from the British Geological Survey website and is very inexpensive, costing only 12 pounds sterling. The map shown above is the new edition of the year 2000. It is different in some respects from older editions. The reader should note though that much of the nomenclature is relatively new to some extent this is just a language matter. If you already know the stratigraphical sequence in the old terminology, it is generally quite easy to translate to the new language. However, and this is the main benefit, much more detail is shown. The Tertiary strata, in particular are well-subdivided in the manner of the 1991 edition of Bournemouth Sheet, 329. A major advance, which started with that map, is the subdivision of the Eocene Poole Formation. These Tertiary stata are very difficult to correlate and the BGS have advanced their mapping far beyond that shown on the older maps.

Of course, no maps are without controversy and different geologists may have different views on mapping interpretations. The new edition does not show major changes apart from new nomenclature and the improved interpretation of the Poole Formation and other Tertiary strata. For the Jurassic and Cretaceous the changes are small. The extent and location of faults is a little different on the new edition as opposed to older editions. Unfortunately, because there is not, as yet, any new Memoir for the Swanage and Weymouth areas, the reasons for changes in interpretation may remain unknown to the public.

The mapping of the Chalk and other parts of the Cretaceous in the area of Harry Rocks, Ballard Point and Studland is broadly similar on old and new editions. The greatest change with regard to the junction of the Cretaceous and the Tertiary in the southwestern corner of Studland Bay. New faults are added on the new edition. The Reading Beds are not shown and the sands in the cliff are shown as a downfaulted block of Poole Formation Sands. (The topic will be discussed further when the Studland - Tertiary Cliffs webpage is revised).

If possible, compare and contrast the two editions of the map when studying a particular area. Thus you will able to see the benefit of newer, more detailed work in a historic context and be able, if necessary to enter into discussion over details of interpretation. You will also be able to grasp both nomenclatural schemes.

Here now is part of the older and simpler map of the Geological Survey of England and Wales, Swanage Sheet, 343 and part of 342. For this area the map is basically the same as the new edition, except for some faults and, as mentioned above, the junction of Chalk and Tertiary.

There is an old, but still useful, explanatory memoir on the area by Arkell (1947). The present map - sheet 343 and 342 is broadly similar to the maps here but the details of some faults have been chaged. The main feature is that the Cretaceous Chalk forms an east-west trending ridge, the Purbeck Hills. The most suitable topographic map for the area is the Ordnance Survey, Outdoor Leisure Sheet 15, Purbeck and South Dorset. Scale 1:25,000.

Melville and Freshney (1982) have provided a brief introduction to the area, that is less detailed and technical than Arkell's memoir, but which is very useful. It uses old lithostratigraphic nomenclature. The field guide by House (1993) is recommended.

INTRODUCTION:

More Historic Geological Maps

An old geological map from Woodward in Braye (1890) is given above. Although the geology is basically correct and and is broadly similar to modern versions, the details of roads and villages are significantly different.

The Geology of the Isle of Purbeck is shown on part of a very old map modified from Damon, 1884. Modern changes in the geological mapping of the area have only been of detail. Some place names have changed since Victorian times. Also provided below is the full map of the geology of the eastern part of Dorset.

STRATIGRAPHY:

CHALK

Introduction - Zones and Lithostratigraphy

A lithostratigraphic scheme for mapping the Chalk by the British Geological Survey has been explained by Bristow et al. (1997), but has not been readily accepted without controversy. This, however, is the scheme used on the 2000 Edition of the BGS 1:50,000 geological map, the Swanage Sheet, 343 and part of 342. It is also used in several papers. It is not used in the British Geological Survey Memoir by Arkell (1947 and later editions), for Weymouth, Swanage, Corfe and Lulworth, because this is of earlier date. No new memoir has been produced as yet; it is hoped that it will appear in the future and then it will explain the details of the mapping. The new lithostratigraphic terminology is not used, of course, in the numerous earlier papers and it is not used on the old edition of the Swanage Geological Map. Therefore the reader cannot depend entirely on the new lithostratigraphic scheme but also should know, as far as possible, the traditional zonal scheme. Without knowing the old scheme, most of the Chalk literature will make no sense. The diagram above should help in memorising the terminology of both. If parts are forgotten then reference can be made to it.

It is clearly important to understand the new lithostratigraphic scheme discussed by Bristow et al. (1997), is reproduced below.

Bristow, R., Mortimore, R. and Wood, C. 1997. Lithostratigraphy for mapping the Chalk of southern England. By Roger Bristow, Rory Mortimore and Christopher Wood. Proceedings of the Geologists' Association, London, Vol. 108, Issue 4, pp. 293-315

The abstract is given below, but the full paper is easily obtainable and it is available online and should be read (Google: Lithostratigraphy Chalk southern England).

Recent British Geological Survey (BGS) mapping in Dorset, Wiltshire, Hampshire, Sussex and Kent has shown that the Lower, Middle and Upper Chalk formations of the Chalk Group, can be subdivided into mappable units of member status. The members are recognizable by their lithology and topographic expression, and can be followed readily across open country. Some members have distinctive wireline log signatures. These members will be shown on future BGS maps. In the above areas, the Lower Chalk (Formation), with its traditional boundaries, is retained and divided into two members, a lower, West Melbury Marly Chalk, comprising, in part, the Glauconitic Marl, most of the Chalk Marl up to and including the Tenuis Limestone; and a higher, Zig Zag Chalk, comprising the top of the Chalk Marl, the Grey Chalk and the Plenus Marls. These members can be readily traced from Dorset and Wiltshire into Sussex and Kent. In the Chiltems, the Glauconitic Marl (s.s.) forms a third, basal, mappable member to the Lower Chalk. The Middle Chalk (Formation) consists of two members: the redefined Holywell Nodular Chalk, comprising the Melbourn Rock and overlying Mytiloides shell-detrital chalks; and the New Pit Chalk, a massively bedded chalk with conspicuous marl seams. The traditional concept defining the base of the Upper Chalk (Formation) at the entry of common flint is too variable and unreliable for mapping. Instead, the base of the Upper Chalk is coincident with a revised base to the Lewes Nodular Chalk, defined by the entry of hard nodular chalk in basinal successions, by the base of the Chalk Rock in condensed marginal successions and the base of the Spurious Chalk Rock in south Dorset and the Isle of Wight. The Upper Chalk is subdivided into a basic framework of 8 members. The coarse-grained, rough Lewes Nodular Chalk is succeeded by very fine grained, smooth chalks, marl-free except at the base, with conspicuous bands of large flints, the Seaford Chalk. The overlying Newhaven Chalk is characterized by firm, marly chalk with numerous marl seams and regular, but fewer, bands of flint. The marl seams locally thin or disappear over tectonic highs. In central Dorset, the base of Newhaven Chalk cannot be mapped, leaving an undivided Seaford and Newhaven Chalk, later renamed Blandford Chalk; the latter name is herein discontinued. In parts of east Kent (Thanet), the Seaford Chalk is overlain by very soft, nearly flint-free chalk, the Margate Chalk. The bases of the Tarrant Chalk and Spetisbury Chalk are defined by the crests of prominent scarp features Ftl and Ft2 in central Dorset. The origin of the features, due to lack of exposure of the feature-forming beds, remains uncertain. These members comprise uniform, firm, white, flinty chalks and collectively, e.g. where not mapped separately, constitute the Culver Chalk of the existing classification. The lower limit of the Portsdown Chalk, with numerous marl seams, is taken at a pronounced negative feature break in central Dorset (base of Ft3 scarp), that approximates to the base of the member as originally defined. The terminal member in Dorset and the Isle of Wight (Studland Chalk), comprising soft, white, marl-free chalk with very large flints, is mapped with the Portsdown Chalk as it is not readily separable from the latter unit.

CHALK:

Fossils

INTRODUCTION;

Conservation and Review of Literature

The cliffs from Handfast Point to Ballard Point are the subject of a section of the Geological Conservation Review. See:
Mortimore, R.N., Wood, C.J. and Gallois, R.W. 2001. British Upper Cretaceous Stratigraphy. Geological Conservation Review Series (GCR), Volume No. 23. Joint Nature Conservation Committee (JNCC), UK. Chapter 3 provides a good summary review of the literature relevant to this area; it is available online at: Handfast Point to Ballard Point (OS. Grid Ref: SZ043824 - SZ048813), Geological Conservation Review, Vol. 23: British Upper Cretaceous Stratigraphy, Chapter 3, Southern Province, England. 11 pp. ("Introduction: The Handfast Point to Ballard Point GCR site, near Studland, Dorset (Figures 3.53 and 3.54), is perhaps the most inaccessible and inhospitable Upper Cretaceous section of all the Upper Cretaceous GCR sites. As Rowe (1901, p. 37) indicated, however, it is also the most important section in the Upper Campanian Belemnitella mucronata Zone, but this can only be worked by boat.") [continues with diagrams, photographs and a useful reference list]

See also the various papers of Gale on the Chalk of this region.

INTRODUCTION:

Relationship to the Offshore Geology and the Isle of Wight

With binoculars or a telescope the Chalk cliffs of the Needles and Scratchell's Bay, Isle of Wight, can be seen in the distance. For more information on these localities go to the webpage:
Alum Bay and the Needles, Isle of Wight.

INTRODUCTION:

Flint in the Chalk - Brief Introduction

Flints are a very fine-grained variety of chert and consist mostly of microquartz and chalcedony, although the details are complex. The microquartz is similar to macrocopic quartz but much smaller. The chalcedony is usually opal-Ct. That is a semi-crystalline intermediate between true opal (amorphous) and quartz (crystalline). Opal-CT contains some water. The chalcedony is not necessarily all of the same type, and a less common variety, lutecite can be present. In addition, within cavities in flint there may some macroquartz. Some porcellanite (very porous white silica) can also occur. Some true opal has still survived within the Chalk away from the flint nodules (Jukes-Browne, 1893 dissolved some chalk to discover this).

The main feature of flint, compared to chert in general, is that it is extremely fine-grained, very hard rock (harder than steel) with conchoidal fracture. The conchoidal fracture is probably the result of the uniformity of the flints. It happens in other fine-grained rocks such as microcrystalline dolomite. The reason for the fine crystal size, much finer than that of chert, is not obvious, but it may in part be the result of replacment of a very fine-grained limestone, the Chalk (compared to, say, Portland Stone, replaced by coarser chert, without good conchoidal fracture).

The source of the silica is probably sponges in the case of the Chalk. Sometimes sponge remains are found within flints producing a hollow centre. Sponge spicules can be preserved in these as "flint meal" (a notable place for finding these in the past in the local region was at a small quarry at the Southampton end of the Winchester bypass).

A curiosity of flints is that when broken and left in a museum for many years the two pieces will not fit together again. This is because of loss of water and some limited contraction.

For more information and a reference list of recent papers see Madsen and Stemmerik (2010) who discuss the diagenesis of flint and porcellanite in the Maastrichtian Chalk at Stevns Klint, Denmark. The sequence Upper Campanian and Maastrichtian Chalk is anomalous in containing the typical combination of evaporite indicators: celestite, lutecite and dolomite (see West, 1973), although it contains common marine fossils and trace fossils.

LOCATIONS IN THE CHALK CLIFF SECTION - INTRODUCTION

Exploring with Dr. Rowe in a Rowing Boat in about 1899

(the introductory parts - other parts of Rowe's account are added elsewhere)

[extract from Rowe (1902). The Zones of the White Chalk of the English Coast. II Dorset, with maps and cliff sections by C. Davies Sherborn, read December 7th, 1900. Proceedings of the Geologists' Association, vol. 17, pp. 1-76. Dr. Arthur Walton Rowe, M.S., M.B., M.R.C.S was a leading medical practioner and councillor in Margate and a philologist, a specialist on the echinoid Micraster, and well-known for his thorough work - The Zones of the White Chalk of the English Coast. C. Davies Sherborn, a great geologist and writer usually accompanied him in the field in addition to drawing maps and sections. Professor Armstrong took the photographs. Although Rowe's work on the evolution of Micraster was thought more important at the time, his zonal mapping is a piece of classic detailed work of historic interest. It is an excellent early report on stratigraphical and palaeontolgical data on the Chalk.]

"This section can be conveniently worked from Swanage, where there is no difficulty in obtaining excellent accomodation. One can walk along the shore, at low water, nearly to Ballard Point, but it was found much quicker to use a boat [a rowing boat presumably hired at Swanage and with a boatman], for the whole section from Ballard Point to St. Lucas' Leap can be worked in no other way. This is unfortunate because unless the sea is calm it is impossible to land along the Foreland.

We note that Upper Greensand begins on the south face of "Ballard Cliff", at a point between the letter d of the first word and the letter c of the second word, as printed on the 6-inch map (Dorset, sheet 57). The beds are here inclined at an angle of 60 degrees, and we trace in succession the Chloritic Marl [Glauconitic Marl], and the zones of Holaster subglobosus, Actinocamax plenus [i.e. plenus Marl], R. cuvieri [Inoceramus labiatus Zone] , Terebratulina gracilis [Terebratulina lata Zone], and Holaster planus. The last zone forms the tip of Ballard Point and appears to be about 20 ft. thick. We can walk on the upturned edges of this inclined chalk, as far as the zone of the T. gracilis. We found it impossible to get on any surface of the Holaster planus zone, even from a boat. The point on the shore where the junction Rhynchonella cuvieri and Terebratulina gracilis zone occurs, is marked by the wire fence which coves over the top of the cliff.

[continues]

[further parts of Rowe's account are added to the particular sections (Ballard Point etc) of this webpage to which they apply]

LOCATIONS - GENERAL

The coastal localities between Studland Bay Tertiary cliffs and Ballard Cliff in Swanage Bay are now considered. They are discussed here from South to North. Zonal detail of the foot of the cliffs is ,mostly after Rowe (1902).

LOCATION:

Ballard Cliff (in Swanage Bay) - Chalk

For more information on the northern cliffs of Ballard Down - Ballard Cliff (or "Whitecliff" in the past) see separate webpage:

Swanage Bay and Ballard Cliff.

Ballard Cliff at the northern end of Swanage Bay is a good location for the Upper Greensand and Lower Chalk, with some fallen blocks from higher parts of the Chalk. It is best studied by walking from Swanage Bay, which is why it is included with that bay in a another website.

(My viewpoint when photographing the above picture above was at the very top of the long grass slopes, three quarters way right on the photograph below. It is a close to a narrow cliff-top path.)

(the eastern part of the landslide backscarp can be seen on the left in the photograph above, and it is completely seen in the photograph below)

Above (top) is a view from a cliff-top path, looking down Ballard Cliff towards Punfield Cove and part of Swanage Bay. A view from the beach and aerial views are also provided. There is no easy access up here to the Chalk. It is too dangerous to reach the outcrops in the spurs. There is a good view, but the cliffs of Punfield Cove are now covered with vegetation. This was once a well-known Lower Greensand exposure. Beyond to the south there are still exposures of Wealden sands and clays, buff and pink in colour. To continue a study of the Chalk it is necessary to descend to the bay by the main footpath which goes down at the end of the Chalk cliffs. The rocky beach can then be followed eastward and there are accessible exposures of Lower Chalk and the Upper Greensand beneath it.

Lower Chalk is present at the foot of the cliff some distance to the east. Pieces of higher parts of the Chalk may be seen as fallen blocks. Molluscan and echinoid fossils may be found. Some Chalk echinoids are shown here and search can be made for Micraster and Holaster etc.

The Cenomanian, the Lower Chalk, has been measured by Jukes-Browne (1903) here as being of about 44m thick (143 feet). Arkell (1947) estimated it as 49m (160 feet). The basement bed consists of about 1.5m of glauconitic, sandy and marly chalk, with phosphatic nodules and many small fossils. It is usually dark grey or green in colour. The ammonoids include Schloenbachia spp., Turrilites costatus Lamark and Cyrtocheilus baculoides (Mantell); the commonest fossils are small rhynchonellid brachiopods (Arkell, 1947).

The Chalk which follows is hard and splintery and contains few fossils. Boulders of it have a blue-grey core and weather to a pale buff on the outside. Cyclical alternations of bluish marl and grey chalk continue upto the Plenus Marl. Fossils are rare. Jukes-Browne (1903) did not find the ammonite Schloenbachia varians above about 9m from the base. About 12m to 15m from the base there are two layers of phosphatic nodules with among them a number of small Calycoceras. Nine metres from the top there is a band with occasional large Calycoceras sp. (Arkell, 1947).

The Plenus Marl can be recognised by its light blue colour. It contains here a few examples of the characteristic belemnite and (Actinocamax plenus) and isolated ossicles of Crateraster quinqueloba (Goldfuss).

The Middle Chalk (Turonian) is exposed, although not easily accessible. It has been found by using the Plenus Marl as a marker horizon. Air-weathered surfaces of the Labiatus Zone and part of the Terebratulina Zone have been reached by walking along the upturned edges of the inclined chalk and climbing a little way up the cliff, according to Arkell. This is a dangerous cliff, though, and any major climbing should not be attempted. People have been stranded on this hazardous cliff. Beware, too, of falling debris! In any case, the chalk is extremely hard and it contains few fossils of interest. It is impossible to get further than the lower part of the Terebratulina Zone by walking along the base of the cliff.

As Arkell (1947) noted, although the cliff section is disappointing fossils can be found from the three zones in the slipped masses and fallen boulders along the beach, from Punfield Cove eastward. Arkell was able to place much of the loose material into zones of origin and find most of the characteristic fossils.

Senonian (Coniacian, Santonian and Campanian) strata above are present in the cliffs beyond but a large part is inaccessible except by boat. Rowe landed by boat at various places and found Cortestudinarium beds immediately north of Ballard Point in a small cave and the other zones in succession up to the fault. All the chalk north of this, as well as a little to the south, is in the Mucronata Zone. Until well into Studland Bay the Chalk is fairly hard, thus allowing the formation of the magnificent stacks (Old Harry, the Pinacles and others) Arkell (1947). Fossils are said to be fairly numerous in the lower division of the Mucronata Zone and more so in the middle which is very soft.

For information on palaeogeography during deposition of the Cenomanian and Turonian parts of the Chalk see Gale et al.(2000).

We landed [from our rowing boat] near Ballard Point on the Terebratulina gracilis beds and found a wonderful air-weathered section.

The double band of yellow-green nodules (the Chalk Rock of the Geological Survey [the Spurious Chalk Rock]) is here well-developed and is, as in all others sections on this coast, well down in the T. gracilis [Terebratulina lata] zone.

[Footnote: A fallen block of this is shown above. It is known as the Spurious Chalk Rock. It is so named because it is a hard band that is below the level of the true Chalk Rock (Stenotaxis planus Zone) and is actually in the Terebratulina lata Zone and at the base of the Lewes Nodular Chalk and it was once mistaken for the true Chalk Rock. The block of this with two glauconitic penecontemporaneous conglomerate beds is from n the shore at Ballard Cliff. This block shown here has fallen from the level of the dangerous bluffs about two thirds way up this cliff.]

This cliff face was studied with fossils, and it is the only exposure in this zone which yielded a good list. We obtained on this small face thirty-five species. From among them we record: Cidaris serrifera, Pentacrinus agassazi, Discoidea dixoni, Hemiaster minimus, Cyphosoma radiatum, Holaster planus; Terebratulina gracilis, Rhynchonella cuvieri, Rynchonella reedenis; Inoceramus cuvieri, Inoceramus brongniarti, and Turbo gemmatus. We also found a splendid frond of Homoeosolen ramulosum, and several blocks of Diastopora oceani.

Before we attempt to zone the chalk south of the Ballard thrust-fault we row along the section in a boat. We at once note that we have grave difficulties before us, as certain spots are inaccessible, even at low tide, and others which are accessible are covered with sea-weed for 10 or 15 feet up the cliff. It is clear then, that we shall probably fail in getting our zonal junction even if fossils are sufficiently numerous to enable us to do so.

As we near Ballard Point the beds become vertical, and we find that the tip and south side of Ballard Point are cut in the Holaster planus zone.

[Ballard Point continued] Zone of Micraster cor-testudinarium

Rounding the point [Ballard Point, coming from the south] we see a cave divided into two parts. The south side of the cave which forms the north side of Ballard Point, in in yellowish nodular chalk, and from this we obtained Micraster cor-testudinarium and Micraster praecursor of the form characteristic of this zone, but should hardly like to give it as much as 85 feet, which is the thickness mentioned by Barrois. In our estimation about half that thickness would be correct.

[Ballard Point continued] Zone of Micraster cor-anguinum

In the northern part of the cave the chalk is whiter, and clearly this in the zone of Micraster cor-anguinum. We could reach no fossils here, so could not determine the zone from zoological data, though there would appear to be no doubt that the chalk is correctly assigned to this zone. Still passing nortwards we round a little point, and enter another small bay. This is also in the zone of Micraster cor-anguinum. Then follows another small point and we enter a bay of considerable size with a shingle beach. The southern one sixth of this bay is still in the same zone, so it would appear that we have a considerable thickness of this bed. We obtained from it a scanty but sufficient fauna to justify us in our determination of the zone of this chalk. Measurement is impossible here.

[Ballard Point continued] Zone of Marsupites testudinarius

[In vertical Chalk just north of Ballard Point]

Still following the beds up we are able to define both the Uintacrinus amd Marsupites bands by their name-fossils. Here the chalk is notably whiter with fewer flint-lines. Fossils are very rare, and we considered ourselves very fortunate to distinguish any junctions at all.

We also found Uintacrinus in little bare patches on the top of Ballard Cliff, close to the edge of the cliff [Arthur Rowe sometimes worked in very hazardous places at cliff edges. See photographs above - he did this too above Scratchell's Bay in the Isle of Wight]. We could obtain no measurement of this zone which was accurate enough to be worth recording.

[continues - with section on Zone of Actinocamax quadratus, but this continues into his discussion of the Ballard Down Fault (Micraster coranguinum Zone) so it is placed in the Ballard Fault section.]

LOCATION:

3. The Ballard Down Fault - Description

Harry Rocks, considered above, is not comparable to the Needles on the Isle of Wight. The Chalk strata at Harry Rocks are almost horizontal. Here, further south, at Ballard Point the Chalk is indeed vertical. Notice how ribs of vertical chalk project seaward (eastward) and are comparable on a small scale to the westward projections of steep dipping Chalk at the Needles on the Isle of Wight. Surprisingly Ballard Point, with its vertical Chalk, does not form the most westerly projecting headland. Consider why and compare with the Needles area of the Isle of Wight.

The notable feature here is remarkable fault in the vertical chalk cliff of Ballard Down. It has long been an object of great interest and Thomas Webster described and figured it in 1816. It cannot be seen from the land but countless visitors have looked at it over the years on the regular paddle-steamer trips from Bournemouth to Swanage. The nature and origin of the unusual curved fault has been much disputed, and it is one of the most famous faults in Britain.

The top two images were taken in August 2007 on a Jurassic Coast cruise from Poole Quay with the Probus Society of Mudeford and Highcliffe. The larger image shows good detail of the fault and associated meso-fractures.

The bottom right-hand photograph was taken by Professor H.E. Armstrong at about the end of the Nineteenth Century and published by Rowe in 1902 (and also by Strahan in 1898). This image is reproduced from Rowe with the permission of the Geologist's Association. It can be compared to the modern photographs, including that of Ameen and Cosgrove (1990) and, incidently, again shows that the chalk cliffs of Dorset are becoming increasingly grassed over; as mentioned elsewhere this surprising in view of a rapidly rising sea-level.

The notable feature is the curved fault plane over almost vertical chalk. The chalk above belongs to the Belemnitella mucronata zone. Rowe found this to be 76m. thick, an unusually great thickness. The chalk to the south of the fault has only been proved to be mucronata zone for 12 m. but more of it may belong to this zone.

LOCATION:

3. Ballard Down Fault continued

- Rowe's (1902) Zonal Investigation

Some extracts from the palaeontological and stratigraphical work of Dr. Arthur Rowe are now given in relation to the Chalk around the area of the Ballard Fault. The heading is "Actinocamax quadratus" but note that the discussion continues unbroken into Belemnitella mucronata Zone, in which the fault is developed.

[Ballard Fault etc] Zone of Actinocamax quadratus [and Belemnitella mucronata - Culver Chalk Formation and Portsdown Chalk Formation]

We then pass [rowing northward from Ballard Point] to a yellower and flintier chalk which extends as far as Argyll Point. The Point is drawn on the 6-inch map but is not named. It was by landing on Argyll Rock that Prof. Armstrong, after many disappointments, and much weary waiting, secured the photograph of the thrust fault (Pl. VIII).

Towards the northern end of this bay we trace two yellow nodular bands, which run almost due east as a ledge terminating in a rock. These bands are strangely reminiscent of the Chalk Rock of the Geological Survey [but much too high for the Chalk Rock]. Close to the point at which the ledge leaves the cliff we fortunate enough to find two very battered examples of Actinocamax quadratus [Gonioteuthis quadrata - a Chalk belemnite and zonal fossil, characteristic of the Culver Chalk Formation]. They were too much damaged to allow of exact determination, but it is certain that they were not Belemnitella mucronata [the belemnite of the top Chalk in Dorset, and mucronate - i.e. ending in a mucro or sharp point]. They could only therefore be Actinocamax quadrata or Actinocamax granulatus (A. merceyi). The distance from the junction with the Marsupites bands excludes the possibility of their being referred to the latter. Much freshwater constantly drips from the the vertical chalk in this part of the bay, and our boatman told us that, in a dry summer, when all other dripping springs dried up, this one still persisted. Throughout the whole of this long extent of Actinocamax quadratus chalk we found no example of C. pillula [Offaster pillula (Lamarck) - zonal fossil of the Newhaven Chalk zone beneath the Culver Chalk Formation, Gonioteuthis quadrata (Actinocamax quadratus) Zone]. But for our definate knowledge of the contact with the Marsupites band, and the presence of two examples of Actinocamax quadratus, we should have been completely adrift. Possibly on a second visit we might be more fortunate in finding fossils.

Passing round Argyll Point we enter another little bay, with springs dripping from the cliff. Here again we found absolutely no zonal fossil. In this bay we saw some very large solid flints, of a brownish colour, which reminded us strongly of the columnar masses of flint we saw south [error - should be north] of Tyneham [near Worbarrow Bay] on the Chalk Ridge. this pit was in the zone of Belemnitella mucronata [Portsdown Chalk Formation], for we found Magas pumilis [a small brachiopod characteristic of the Portsdown Chalk Fm.] but no Belemnite. In the case of this bay, however, we found no zoological evidence whatever to justify us placing it in the Belemnitella mucronata zone. We therefore, for want of better evidence, refer the chalk in this bay to the Actinocamax quadratus zone. We may remark that we found the top of this zone at Arish Mell almost equally devoid of fossils.

[Note the implications of the above comments - the base of the mucronata Zone (Portsdown Chalk Formation) was not proven by Rowe. Therefore the extent of repetition by the Ballard Down Fault is not known exactly, and it is possible that it could be greater than has been assumed since Rowe. This might have implications relating to structural interpretations of the fault.]

With the exception of this little bay we can work no more of the face of the cliff until we come to the fault, for the cliffs are obscured by sea-weed to a height of 15 feet. The only way to zone this chalk would be to work it with a ladder, and we regret that the one which we took with us was too short for the purpose.

It will be seen from this description that we have here a wide extent of chalk, based by a definate contact with the Marsupites - zone, and clearly not in the Belemnitella mucronata - zone. Had it been in the latter we must have seen examples of the name-fossil, which is found in abundance on the north side of the fault, close up to the curve [it is interesting that belemnites - B. mucronata - are abundant on the hanging wall]. It is evident that whatever the thickness of the A. quadratus - zone may be, it must be very considerable, thus, in some measure justifying the large measurements of this zone which we obtained at Middle Bottom and Arish Mell.

That the Actinocamax quadratus - zone does not extend up to the fault is quite clear from the fact that we found a fine example of Belemnitella mucronata above the seaweed line 39 ft. [11.9 metres] south of the fault; and in the cave, which the sea has eaten out in the line of weakness caused by the fault, we found two examples of the small Echinocorys, shaped like an Echinoconus [is this an older name for Conulus?], which we found in the same position at Arish Mell, and regard as characteristic of the lower part of the B. mucronata - zone.

Dr. Barrois [1876 - classic French work] places the chalk on the south side of the fault in the "Zone a Belemnitelles", but assigns that on the north sid of the fault to the zone of Marsupites testudinarius. While we find no mention in his text that he found B. mucronata chalk on the south side of the fault, his diagram (Pl. III, fig. 7) leaves no doubt upon the point. We now know that the his supposition of B. mucronata chalk on the south side of the fault is substantiated, but that there is no ground whatever for placing that on the north side in the Marsupites - zone. Indeed it is difficult to see how he entertained the latter idea at all, for the whole cliff from the fault to Studland Bay, is cut in the B. mucronata - zone, rich in the name-fossil, and in all other characteristic fossils associated with it, and at the time of our visit perfectly exposed and accessible in its entire extent.

From Ballard Point to the fault we have, then, nothing but vertical chalk, ranging from the H. planus - zone to that of B. mucronata. The chalk is hardened and altered to a remarkable degree; it breaks with a conchoidal fracture, is much slickensided, and even the flints are crushed and shattered. On this point Mr Strahan writes:" Under the microscope many perfect foraminifera can be detected, showing that although there has been reconstruction and cementating, the rock has not been perfectly crushed" [this would not expected]....
[further notes from Strahan follow, including comments that the Chalk has the same general chemical composition above and below the fault - as would be expected]

We see that the fault has taken place in the zone of B. mucronata, and that it runs out, east of Middle Bottom through the zone of Actinocamax quadratus [Note that the first point is generally accepted. It is not now considered, though, that the fault is laterally very extensive and that it continues westward to Middle Bottom (between Durdle Door and White Nothe), but simply that the foresyncline is seen there in the A. quadratus zone].

[end of extract from Rowe]

LOCATION:

3. Ballard Down Fault continued

- Origin - Earlier Work

A northward thrust ramp and subsequent rotation interpretation of the origin of the Ballard Fault has been given by Ameen and Cosgrove (1990). Diagrams above provide a simplified explanation of this theory. This mechanism is well-known but may not be correct. Other possible mechanisms are shown below. Attention should be given particularly to the hypothesis of (Carter, 1991) because this is recent rival to the Ameen and Cosgrove (1990) theory. It involves movement in the opposite direction, that is from north to south (see more on this below).

If you study the geological maps you will note that the low-dipping Upper Chalk is at the surface in the Studland area north of the fault. Elsewhere it is buried under Tertiary strata. This suggests the the mechanism for formation of the fault also raised the top of the Chalk north of the fault at Studland. A good theory for the origin of the Ballard Down Fault should also account for this. Those mechanisms involving downward movement of the Mucronata Chalk to the north would also produce a higher top surface of the Chalk. It seems that they can explain this. However, this is not conclusive evidence in their favour. Some type of upthrusting from north to south might cause this effect.

LOCATION:

Ballard Down Fault - Seismic Evidence

A recent key paper regarding the Ballard Down Fault is that of Underhill and Paterson (1998).

Underhill and Paterson Paper - Lyell Collection, Geological Society of London.

They investigated by studies of offshore seismic the relationship of key structures of the Purbeck - Isle of Wight disturbance. They have shown an important N-S diagram showing a cross-section parallel to the coast and west of Swanage Bay. They have provided a clear explanatory diagram towards the end of the paper (obtain the paper and see this - a rough version is shown below). Their conclusions, which follow, further below:

"..the seismic data is entirely consistant with Carter's model which requires the least dramatic structural geometry at seismic scale (their fig 16). The implications from the seismic data is that the Ballard Down Fault is a local, late-stage back-thrust superimposed upon the earlier and more structurally significant Purbeck Disturbance."

Ballard Fault - Argyll Rock

Argyll Rock is an offshore, platform that only dries out in certain low tide conditions. You can see the waves breaking on Argyll Rock in the large modern photograph of the Ballard Down Fault above. Bruce (2001) commented that the rock is about 50 metres from the cliff and like a giant table top. It was named after a fishing vessel that was wrecked there.

I have not been to Argyll Rock but it seems to be part of the footwall of the Ballard Down Fault. It is presumably the remaining root of a large sea stack that has been eroded. The hard chalk of the footwall is more likely to have provided relatively resistant rock for such a stack.

Argyll Rock was used for photographing the Ballard Down Fault by Professor Armstrong for the paper Rowe (1902). He would have used a tripod in those days because of slow photographic exposure times. Thus, as mentioned in Rowe's paper he had to land on Argyll Rock when it was exposed in quiet sea conditions. He would have been quite close to the fault and needed a very wide-angle lens.

(Note - a little speculation. Argyll Rock is, as mentioned above, almost certainly the relics of a large sea stack. Could this have been the "Bollard" which gave its name to Bollard Point and Bollard Down, now known as Ballard Point and Ballard Down? Perhaps there is some other explanation for the Bollard name. Local historians may know more about this.)

LOCATION:

4. Ballard Point to The Pinnacles

This stretch of coast is in the zone of Belemnitella mucronata and within the Portsdown Formation. Rowe (1902) did not provide specific details other than this zonal information.

LOCATION:

5. The Pinnacles (Sea Stacks)

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Two Chalk stacks called the Pinnacles are present to the southwest of Harry Rocks. The northern one, is known as Little Pinnacle, Haystack, Turf Rickrock or the Wedge. This, which is shown in an old photograph, is shorter than the southwestern one. The latter is the Pinnacle, (bottom centre) and is now triangular in section and looks pointed in some views. As Bruce (1989) mentioned, in old photographs, like that shown on the bottom right, it is as high as the cliff and with a small crown of grass on top.

At the turn of the 19th century peregrine falcons nested in a hole at the top of the Pinnacle (there are some birds there in the photograph above, but, of course, they might be seagulls). In the words of Hardy (1910) :
"Agglestone Rock has been the habitation of a pair of penegrine falcons for ages back. They rest and hunt there, but build their nest and rear their young on the top of Pinnacle Rock, near Old Harry. Their nest is artfully concealed in a hole in the summit, which has an opening at both ends, through one of which they enter, emerge at the other, the nest being most skilfully concealed from all nest seekersor destroyers of their own or any other species. The reason why these birds can be so seldom seen is because of their wonderful keen sight, for as soon as the "man with the gun" is observed at the most distant range, the birds swoop down from their aerial abode and wind their flight to their retreat to the Agglestone or some other isolated spot, long before the eye of the fowler has detected them. This pair of falcons is one of the five pairs known to reside on the Dorset coast, the abodes of the others being Blacker's Hole, St. Alban's Head, Whitenose and Portland. Another remarkably interesting point is that, if one of the birds is killed, the survivor makes off to Scotland to procure another mate, and returns with it again to its former haunts."

These stacks have been formed by the erosion and cutting off of headlands. Parson's Barn, a high arched cave, was situated to the north of the northern pinnacle but has since collapsed. The ground above is known as Old Nick's Ground.

The aerial photograph, top left above, shows a small promontory on the far right of the photograph, and actually very close to Harry Rocks. This promontory is a natural arch, although that is not visible in the aerial photograph. Compare the coast here with that at Bats Head, near Durdle Door, Lulworth. There you will also encounter a rather similar stack and a natural arch in Chalk (in contrast, the strata there are vertical, though).

This stretch of coast is in the zone of Belemnitella mucronata and within the Portsdown Formation. Rowe (1902) did not provide specific details other than this zonal information.

LOCATION:

6. Between The Pinnacles and The Foreland (No Mans Land)

The images above show the locations of the first two headlands southwest of The Foreland and Harry Rocks. The most obvious of these is the first headland which has "The Arch" a natural arch beneath it. This is a much broader headland than the others nearby, and easier to walk out on. Eventually the chalk at The Arch will collapse and a new sea stack will be formed.

The bay which lies to the south of the headland with The Arch is interesting because it contains a beach of flint pebbles. These have increased the erosion as a result of abrasion of the chalk, and thus the cliff here is undercut. There has been a recent (as seen in July 2009) cliff fall in the northern part. Bruce (2001) commented that flint pebbles from the grey beaches in this area used to be collected for facing local houses.

This stretch of coast is in the zone of Belemnitella mucronata and within the Portsdown Formation. Rowe (1902) did not provide specific details other than this zonal information.

LOCATION:

7. The Foreland (No Mans Land) and Old Harry Rocks

LOCATION:

7b. No Man's Land (The Foreland) and Old Harry Rocks - continued

The Foreland, Handfast Point or No Mans Land

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The promontory of Old Harry Rocks, in general, has been referred to as Handfast Point, but there are other names in addition. A large mass of Chalk forming the Foreland was joined to cliff at the beginning of the 19th Century by a narrow ridge (Davies, 1935, 1956), but this is now broken with just an incomplete and dangerous relic remaining (see the photographs). The isolated, small island of Chalk is known either as "No Man's Land", "No Mans Land" or "The Foreland" [the names, The Foreland or No Man's Land are used here indescriminately, and both refer to this isolated block. It was once the foremost land, but now it is accessible to no man!]

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Because of incipient development of Inversion, The Chalk here is uppermost in Dorset, but does not correspond to the uppermost in Europe.

[Explanatory Note regarding Chalk: This region is well-known to be part of an Inversion Structure, with a basinal area to the south in the Jurassic and continuing to Late Aptian times; the southern basin was uplifted in Eocene times onwards, but this "Inversion" had already had indications of limited development during late Cretaceous (this can be seen from Chalk thicknesses). The Inversion Structure is liable to oversimplification, because in addition, there is an easterly tilt under the basal Albian Unconformity. It is not, as is might be considered by newcomers to the area, just a simple two-stage phenomenon]

At Old Harry Rocks, the Chalk strata belong to the Portsdown Chalk Formation of the Belemnitella mucronata Zone (See the BGS Swanage geological map, latest edition). In old terminology this would be the uppermost part in Dorset of the Upper Chalk. It is Campanian in age and there is no Maastrichtian Chalk here (although there has been in the past in the broader region, probably on the southern Isle of Wight (the evidence is from reworked flints in the Boscombe Sands at Bournemouth). Here, at Handfast Point this Campanian Chalk has a very gentle northerly dip, more specifically, a little west of north at an angle of 8 degrees (Strahan, 1898, p. 170). Recent mapping has not changed the general interpretion greatly, but the faulting at Studland is shown differently and the old "Reading Beds" outcrop has been reinterpreted, showing Thames Group, London Clay Formation, directly above the Chalk (a non-sequence or gentle unconformity). Contrast with Alum Bay (Isle of Wight Geological Sheet) where Reading Formation overlies the Chalk.

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It is easy to walk by the cliff top to Harry Rocks from Studland. There is good straight path from the village across some fields. Care has to be taken here, though, because there are precipitous cliff edges. Although it is not yet 4 pm, but because it is late November, the sun is beginning to go down, giving a reddening sky. Notice how the waves approaching from the south have swung round the headland by wave-refraction.

A selection of photographs of Harry Rocks is given above; some are aerial by courtesy of the Channel Coastal Observatory . Other photographs are of various dates and taken at various angles.

As shown in the photographs, adjacent to the headland the cliff is strongly crenulate, with small bays and small promontories cut along joint planes. Erosion has separated the stacks of Old Harry Rocks and the Pinnacles, further south (Bird, 1995). These have been gradually reduced over the centuries, some of the earlier stacks having fallen (old Harry's original wife fell in 1896), while new ones have been formed by the breaching of narrow isthmuses. The history of this headland is interesting. Ralph Treswell's Map of 1585 shows Studland Castle, alias Handford Point. There was once a pinnacle seaward of the castle. In 1624 only a block house remained. Three or four guns were mounted at this promontory (Legg, 1989). May and Heeps (1985) illustrated the development of stacks on the coast around here, using maps of four different editions during almost one hundred years (1887-1982).

The present island of The Foreland No Man's Land is a long and quite large stack with caves and forming natural arches ("The Arch" is not here but in the first headland to the south of it) . Probably once a single feature, No Man's Land is now broken through in the central part and is really two large stacks. This is not obvious from the cliff top and best seen from the beach.

The large stacks were connected to the mainland in the not too distant past. In 1770 a man could creep along a narrow path from the mainland to Old Harry Woodward (1890). Notice the almost horizontal chalk, some bands of flints, and the cave through the western (landward) end. In the left-hand photograph waves are emerging from this cave. The right-hand photograph taken from the sea in September 1997, shows the relationships of the stacks viewed from the south. In the far distance, the large drilling rig at Goathorn Peninsula is occasionally just visible. From here were drilled the extended-reach oil wells into Poole Bay.

Mr Penny in Mansel-Pleydell (1888) commented on the situation prior to the fall of Old Harry's Wife in 1896.
"During the last 50 years the chalk cliffs at this point of the coast have considerably worn away by the action of the weather upon them, but Old Harry Rock still stands with his wife, like giants in the base. Old Harry still stands high and dry at low water, and may be got at from the shore, but not so easily as 50 years ago; the channel, however, is not materially widened, the cliff opposite these rocks rocks being, like the rocks themselves, nearly unaltered, and very hard, they have resisted both the wind and the sea. The denudation of these cliffs has occurred some distance from the point, and, probably, in the course of years another large piece of the cliff will be detached from the main land and form a rock of considerable size."

In 1898 Strahan noted that: "Several great columns of chalk, two of which are known as Old Harry and Old Harry's Wife, stand detached from the parent-cliff, but still preserve a small patch of green-sward on their summits (Old Harry's Wife - Destroyed by the sea in 1896, after this description had been written). A much larger mass [of chalk], now forming the promontory of Handfast Point, is connected with the mainland by an extremely narrow neck, and will, before long, be disconnected."

You can see the site of the narrow neck in Strahan's cliff drawing, shown above and in the photograph from much about the same date. This has since broken through and the Foreland or No Man's Land is now separated. The sketch and photograph also shows that the Pinnacle was higher at that time (see below) and note the position of Parson's Barn (see the footnotes) which has since collapsed.

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Footnote: The Name - Old Harry
There are two theories about the origin of the name "Old Harry". One is that the rocks are named after the Poole smuggler and pirateer, Harry Paye. He would have sailed past here on numerous occasions. He had his headquarters on an island in Poole Harbour, very close to Studland.

A second theory relates to the devil. "Old Harry" was a medieval name for Satan (Bruce, 1989) and, according to legend, the Devil is supposed to have rested here. The land on the cliff top opposite is called Old Nick's Ground. Other local legendary connections with the devil include the Agglestone or Devil's Night Cap (Woodward, 1890) supposedly thrown by the devil from the Isle of Wight. Nearby is the Puckstone. There is another rock with a similar sounding name - Arish Rock - one of the Mupe Rock. Arish Mell is a nearby cove. I do not know the origin of these names.

Footnote: St. Lucas Leap (and Buddy Leap)

The area of the former narrow connection between No Man's Land and the mainland is known as "St Lucas Leap". It is where a pedigree greyhound is said to have dropped over the cliff while coursing a hare (Legg, 1989). More information was provided by Hardy (1910) . "It was close by, at St. Lucas's Leap, that a pair of pedigree greyhounds belonging to a certain squire at Studland, while coursing a hare, are said to have leaped clean over the cliff and have been dashed to pieces, the name St. Lucas being afterwards given to the spot where the tragedy occurred to commemorate the name of one of the favourite hounds which perished so suddenly and tragically. It was said that the old gentleman did not long survive the disaster, as he was so greatly attached to the dog and its fortunes."

The St. Lucas Leap event was duplicated by chance on the 12 February 2009, although this time the dog survived:

"A springer spaniel was described as a "lucky boy" yesterday after falling 30 metres (100ft) down a cliff and then swimming to safety on a yacht that was almost a mile out to sea. The dog, Buddy, chased a rabbit over the cliff edge and landed in the sea. He tried to scramble back up only to fall into the water again. His owner, Steve Kingsley, spent almost three hours searching for him on Monday afternoon until a yacht crew told coastguards that they had picked up and exhausted dog out at sea and given him food and water. A jetskier then gave the five-year-old Buddy a lift ashore." (Guardian Newspaper 13th August 2009).

Footnote: Legend of the Bells, and Parson's Barn
(From a late Victorian fictional story, set in the mid 18th century and loosely based on some Dorset legends and facts - and published by Climenson in 1906)
"Hoisting the main sail, we proceeded at a rapid pace through the waves to the point, Eva seated beside Markham, who guided the "helum," as he called it. Near the point Markham desired Tony to tell Eva the legend of the Bells. Pulling a lock he began:
"Leady, they do zay as zome many yeares ago a vessel wer' a-zailing to Poole wi a peal o' bells vor Poole Church, an' the zailors did meake a mock o' 'em, an' did laugh at 'em, an' at Zunday, an' avore they knew they wer' anighst, 'Old Harry' took 'em at ther' word, an' zent a starm, an' the weaves ran the bwoat on the rocks, an' all wer' drownded, an' the bells at the bottom o' the zee. At ivery starm voks can hear em gie a peals to warn 'em aff. It be a wold teale."
Rounding the point, Markham ordered the main sail to be lowered, and getting into the little boat with Tony to row us, we landed close to "Old Harry" on some huge blocks of stone, as if the Titans had been playing ball there; a crowd of herring gulls, guillemots and cormorants flew round from their nests on the summit of the rock pinnacle, and clefts in the cliffs, whilst a couple of Puffins (true little Sea Parrots) dived off the rock, their queer little orange, blue and red bills, and red legs, looking charming through the clear water. Scrambling carefully over the slippery rocks, we reached a cave called the "Parson's Barn," an oval-shaped opening, some forty feet high. In cracks in the stone, grew the Sea splenium and Samphire plants; the floor was of soft glistening sand. Markham told us some year or so back, in and a neighbouring cave, a quantity of tobacco was found, which been evidently for a long time, as it was ruined by exposure, the Smuggler who placed it must have been long dead or left the country. Suddenly the keen eyes of Markham perceived a bung floating on the water, and he desired Tony to see if it was a lobster pot. After some tugging, not a lobster pot, but a small four-gallon cask of Brandy was hauled up, at the bottom of the cask, a rope attached it to a bar of iron with hooks at the end, which we were told was called a Rock grappler. Markham declared this cask had been placed no doubt in payment for services rendered by some fisherman, who would fetch it at his convenience, but he added, "the rascal shall be sold", so placing the cask in the boat, we returned with prize to the Cutter, and hoisting sale made for the bay of Swanage."
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Returning to the Chalk strata, Strahan (1898) commented that here they are nearly horizontal, dipping at 8° in a direction a little west of north. The chalk is not much altered and shows little sign of tectonic action other than a few small faults and joints with slickensides. The joints, however, have the effect of causing the cliff to break away into roughly rectangular masses, and give it an appearance which led Webster (1816) to compare it to "a work of art, an huge bulwark erected to oppose the force of the sea."

At the Foreland there is a basal ledge, prominant around the stacks, and sectors of intertidal wave-cut ramp with clear white scoured chalk. There is no shore platform, but the vertical cliffs and fallen boulders rise behind an abrasion platform that is submerged even at low tide (Bird, 1995).

LOCATION:

7. The Foreland and Old Harry Rocks - continued

The Yellow (or Brown) Bands

(Note: At present there is a little uncertainty as to whether there are only two or whether there are three or more yellow or brown bands at No Man's Land. The labelling of yellow bands as "upper" or "lower" on the illustrations is not necessarily correct now and may be modified later.)

At Old Harry Rocks and No-Man's Land the yellow bands of Rowe (1902) are clearly seen and are accessible. They also well seen in the Chalk cliffs of Studland Bay. Both localities are considered here. The yellow bands are not obvious sedimentary features such as penecontemporaneous conglomerates or clay bands in the Chalk. There are no rounded clasts but open fractures with associated angular breaks. They seem to be shear planes that are roughly parallel to bedding.

There seems to have been some movement on these and it has not been entirely smooth and regular and instead, in places they change stratigraphical horizon to a limited extent. Thus pull-apart structures can be seen and these reveal the sense of movement.

At No Man's Land and at Old Harry's Wife the yellow bands, the shear planes, start to dip more steeply northward as the northern edge of the Chalk outcrop is approached. Between the two yellow bands there is some oblique shearing of the Chalk, although there is no obvious indication that these secondary shears have caused much displacement. The extent and direction of displacement on the yellow bands, if there is any substantial amount, is not yet known. The yellow bands curve parallel to the fault plane. Do they represent some major bed-over-bed sliding? Crossing them but without any vertical displacement are the strike-slip shear planes or faults. The relationship of both these structures to the Ballard Down Fault is not known. Unlike the Lulworth area, there are no major thrust planes, and the tectonics are clearly different.

The yellow bands seem to be pathways for ferruginous water flow through Chalk. The coccolith limestone is probably not very permeable, partly because of the usual problem of very fine particle size. In addition, though, in this area there has been some tectonically-caused recrystallisation which has hardened the Chalk. Perhaps some horizontal displacement on an irregular surface has caused the yellow bands to have opened up a little. Thus they may be thin but extensive, sub-horizontal gaps in the strata. Thus water flow through such gaps was facilitated. This would explain the occurrence of clay washed into them, particularly at or near the Studland Bay Chalk cliffs. At that locality small-scale solution pipes are associated with a yellow band, so there is little doubt that they have passages for water flow. Further evidence for this, shown in a photograph above, are limonitic festoons on a joint surface below a yellow band showing where ferruginous water from the yellow band has seeped downward in vadose conditions.

LOCATION:

7. No Man's Land and Old Harry Rocks - continued

Strike-Slip Faulting

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Nearly vertical strike slip faults occur near to Old Harry Rocks and at the Pinnacle (and probably elsewhere). In all examples seen the strike-slip movement is exactly parallel to the bedding. At the Old Harry location it seems to be later than the bedding-parallel slipping of the "Yellow Bands". It is dextral at that locality. At the Pinnacle strike-slip faulting is also bedding-parallel in direction. Generally the dip of the Chalk north of the Ballard Down Fault is very low, almost horizontal. It steepens a little to 8 degree in a direction a little west of north at Old Harry Rocks (Strahan, 1898). Thus the slab of Chalk north to the Ballard Down Fault turns down and little at Old Harry Rocks before disappearing beneath the Tertiary and the sea.

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LOCATION:

7. No Man's Land and Old Harry Rocks - continued

Rowe's (1902) Zonal Investigation

Some extracts from Dr. Arthur Rowe's palaeontological and stratigraphical investigations on the Chalk of this and adjacent stretches of coast are given.

"Leaving the fault [the Ballard Down Fault] we pass northwards, and save for a few points at which the cliff is clad in sea-weed, or battered by the sea, we have a rich cliff-section in B. mucronata - chalk, 1 and three quarter miles [2.8 km.] in extent. Nowhere on the English coast is this zone so admirably exposed as here. The beds, horizontal at first, dip gently to the northat at about 10 degrees as we approach Handfast Point [The Foreland or Harry Rocks]. The chalk shows but little trace of alteration, but we notice a few small faults and occasional slickensiding. Some of the flints are cracked, but on the whole they are fairly intact, running in irregular lines. Sometimes the flints are very large, especially in the highest beds in Studland Bay, but there are no "pot stones" like those seen at Runton or in the Norwich Chalk. We no longer see veins of calcite and though the conditions have greatly improved, the chalk differs greatly from the that in the horizontal beds around Wool. Inland the chalk can be crushed between the finger and thumb; on the coast, it has been compacted considerably, for while we can cut it with a chisel, it is anything but soft, and the cleaning of the fossils, if not actually impossible, is only effected with the greatest difficulty. All large fossils are broken, and a perfect Echinid is a great rarity. In the same way, Belemnites are frequently broken in several places, the fragments being considerably displaced.

But though it is most difficult to obtain good specimens from this chalk, it is possible to procure, even in moderate time, a fair number of identifiable forms. The fauna will be discussed in detail in the zoological summary, and it will be sufficient to say now that it differs in no important way from the normal.

It will come as a surprise to some that we have here a coast section in B. mucronata - chalk, which is at least 250 ft. [76 metres] thick. For the present we must ignore the B. mucronata on the south side of the fault, which we know to be at least 39 ft. [11.9 metres] thick, and begin our measurements at the fault itself. If we take a linf from the cave at the foot of the fault so that it intersects the middle of the curve at right-angles, we find that it reaches a strong line of nodular flint [see Rowe's cliff section]. This flint-line is 100 ft.[30 metres] from the curve. We follow this strong flint line, and find that it comes to the shore 100 yards [approx 100 metres] north of the First Pinnacle [The Pinnacle]. At this point we see two yellow bands at the top of the cliff, the lower strong and constant, and the upper one weak. The upper one dies out as we go north. There is roughly 100 ft. [30 metres] between the strong flint-line and the strong yellow band. This yellow band can be traced readily to Handfast Point and Old Harry [Rock] show it well. It is about two fifths up the cliff at Handfast Point and gradually sinks as we pass into Studland Bay, till it reaches the shore at the fifth little headland west of Handfast Point. There is about 50 ft. [15 metres] above the yellow band in Studland Bay, so we can obtain a thickness of B. mucronata - chalk (as exposed) of at least 250 ft. [76 metres]. As far as we can tell, the measurements given are, if anything, under-estimated. We believe that this is the first time an adequate estimate has been given of this zone on the Dorset coast, or that the approximate thickness has been gauged anywhere in the south of England. [end of section on the Harry Rocks and Studland cliffs]

LOCATION:

8. Studland Bay Chalk Cliffs

General

See also:

Studland - Tertiary Strata webpage.

As mentioned above, at low spring tide it is just possible to walk along the foot of the cliff to Harry Rocks. The Chalk here is Campanian and of the Mucronata Zone and dips at a low angle northward. It is not very fossiliferous and the zonal belemnite, Belemnitella mucronata, is not easily found. This Chalk contains the usual type of early-formed flint nodules but an interesting feature is the presence, in addition, of thin veins of flint at various angles to the bedding. At the Studland (western) end of this Chalk cliff section there is a conspicuous unconformity with Tertiary Reading Formation lying on a hummocky eroded surface of Chalk. At the junction there are large irregular flints eroded from the Chalk and much limonite (iron hydroxide). Beneath this surface there is some brown iron-staining.

The north-facing Chalk cliffs of Studland are sheltered from the prevailing southwesterly winds and waves. It is rather surprising that the cliffs are vertical in a place where there is so little obvious erosion. There is, however, much bioerosion, the work of marine organisms and some grinding away of the chalk by sand and pebbles. The foot of the cliff can be undercut a little resulting, sooner of later, in cliff falls, although they are relatively rare here. The cliff almost follows the junction of Chalk and Tertiary.

Studland Bay is an interesting place for marine life and contains sea-grass. A recent invader is the Japweed or Japanese Seaweed - Wireweed, species - Sargassum muticum. Large masses of this can be seen from the cliff top to the west of Harry Rocks, if suitable safe viewpoint can be found.

LOCATION:

8. Studland Bay Chalk Cliffs - continued

Flint Nodules

An unusual feature of the mucronata Chalk of the southern cliffs of South Beach, Studland Bay is the occurrence of oblique lenses or veins of flint developed in the planes of small normal faults. These are extensional faults with fault planes hading at about 45 degrees. The faults seems to trend roughly north south but no accurate study has been made. Downthrow in at least one case is to the west and is small, only about 12 cm.

The question is whether some flint formed very late or whether there was some very early extensional faulting. The fact that one of the flint veins is attached to a "normal" flint and the original fault plane seems merged indicates an early origin. However, one of these veins, as shown above is closely associated with ferruginous deposits, and they even occur within the flint. There a strange laminated ferruginous and siliceous deposit which occurs in nearby cavities. The details or origin of this is not known. The ferruginous nature and the presence of associated cavity fill deposits points to association with piping. There is an interesting puzzle here.

(In any discussion of this topic it should not be assumed that development of chalcedony from opaline silica was necessarily a "one off" event. Very fine-grained opal is still present within the Chalk, but is easily missed in thin-section because it is, of course, isotropic. Thus, in theory, more flint could be formed even now by remobilisation of this amorphous silica. See an old paper on this subject.)

LOCATION:

8. Studland Bay Chalk Cliffs - continued

- Solution Pipes

See also:

Studland - Tertiary Strata webpage.

Solution pipes containing brown argillaceous material are developed near the Chalk-Tertiary junction in the southwestern corner of Studland Bay. These were once quite well-exposed here. Unfortunately degradation of the cliff and the growth of vegetation means that their details are not very well seen at present. It is not surprising to find them here so near the Tertiary outcrop.

There also appears to be one in the roof of a cave through one of the No Man's Land stacks. When you walk through the cave you will notice a brownish cavity quite high above your head. It does not seem likely that this is simply the result of marine erosion. It is too high and seems to be the washed-out remains of a solution pipe. It is situated at a location where the Chalk is very sheared, with near vertical shear-planes.

It is suprising that solution pipes in the cliffs south of Harry Rocks are very small and mostly contain a brown sand. The features observed may also have been affected by some cryoturbation. The low dip of the Portsdown Chalk Formation would suggest that the Tertiary was not far above. Large pipes would be expected here, so thus some special explanation is needed for their absence.

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QUATERNARY:

Blown Sand Deposit above the Chalk

Description of the Sand Deposit

An interesting feature of the top of the Chalk cliffs and the footpath at Old Nick Ground is the rather patchy occurrence of up to about half a metre of brown blown sand, mostly of medium grain size. It is best seen in the area of The Pinnacle, and here it is thick enough for the occasional rabbit burrow. This sand is notable for containing rounded sand grains that have abraded on sand dunes.

The sand deposit lies above the cryoturbated top of the Chalk and a residual deposit of flints. It descends into small solution pipes. It does not show major evidence of cryoturbation and it does not contain many flints.

Possible Explanation 1 - Holocene Blown Sand from a Previous "South Haven Peninsula"

The apparent stratigraphical position, above cryoturbated, uppermost Chalk, suggests a Holocene origin. At present there is no easy route for sand from the Studland sand dunes of the South Haven to reach this site. The Chalk cliffs of southermost Studland Bay are a barrier. Now sand can be blown up cliffs, and this has happened quite extensively at Eocene sand cliffs of Bournemouth. However, there is no sand (other than traces of this) in the cliffs and there is no sand beach at the base. The nearest beach sand is more than a kilometre away at Studland.

At some time in the past it is probable that there were active sand dunes much closer to this area. They may have existed directly to the north of the present Foreland peninsula, before Studland Bay had retreated landwards (i.e. westward). If the source was coastal sand dunes during the Holocene, then it is unlikely that the sand transport took place much before about 4000 BP, because it was not until then that sea-level had risen sufficiently to bring the sea into this area (the Neolithic still-stand is a further complication not discussed in detail at this stage).

Possible Explanation 2 - Raised Beach Origin

It is possible, although not necessarily likely, that the sand represents the relics of a raised beach. Shells were not seen in it, but the sediments have not been properly investigated. The height of the sand above sea-level is about 50 metres. This is too high for the Ipswichian raised beaches (i.e. Portland raised beaches). However it is not far above the height of the earlier Goodwood-Slindon-Boxgrove raised beach on the Chalk of Sussex which has a maximum height of about 40 metres.

Possibly supporting the high raised beach theory is the evidence from cryoturbated solution pipes. Small pipes containing brown sand have been distorted by cryoturbation in some cliff top exposures between Harry Rocks and the Pinnacles. Thus the surface here is an old one, of Pleistocene origin and not the result of later post-glacial erosion.

A further point of evidence, not yet investigated properly, is that small ovoid pebbles that are very well rounded, occur in the soil near to the sand deposit (they can be seen in the footpath). The rounded pebbles are mixed in with the usual angular flint debris. There is more than one possible explanation for the pebbles, though. They could be residual Tertiary material (like London Clay ovoid pebbles), perhaps preserved in a local solution pipe. An anthropogenic origin does not seem likely because there is no obvious source nearby for pebbles of this type.

Possible Origin 3 - Pleistocene Loess

Another possibility is that the blown sand is some unusually coarse variety of the Pleistocene brown silt known as "Brickearth". Although some of this may be alluvial silt, some at least has been regarded as a type of loess, a blown silt deposit.

Relationship to the Yellow Bands?

As noted, the thin sand deposit occurs near the Pinnacles. This is where the main and most conspicuous yellow band (discussed in another section of this webpage). starts to descend from the land surface above the cliff. This may be coincidental, but there is a possibility that ferruginous Quaternary sediments here have supplied the iron for the staining of the yellow band. At the moment this is only speculation.

HARRY ROCKS - PETROLEUM GEOLOGY

Old Harry - 1: Oil and Gas Prospect

(For more on Petroleum Geology in the region see:
Petroleum Geology, South of England.)

There was an Extended Reach Borehole from Wellsite M, in 2000, to a prospect to the east of Old Harry and Harry Rocks, between Studland and Swanage (near Ballard Down and Ballard Point). It seems not to have been successful in economic terms but is of interest in showing some structural and stratigraphic features beneath the sea floor east of Harry Rocks.

The well was drilled by the Operator of Wytch Farm at the time, BP (since sold by BP to Perenco UK). The objective was a prospect of limited size in the the northern, downthrow side of the Purbeck faulted Monocline or Purbeck - Isle of Wight Disturbance. In relation to the cliff section, it was effectively north of the Ballard Down Fault.

A brief technical report is available on the internet: DECC, Department of Energy and Climate Change, Government of UK. Relinquishment Document of DECC, Government of UK, Licence Block P1022 (Block 98/11). The general comments here are based on this report, but written in non-technical language. The illustration above is based on, with modification, on part only of the map: Fig. 4, Map displaying Block 98/11 Discoveries, Leads and Prospects.

The well, entering obliquely from the direction of Goathorn Peninsula, drilled through 60 metres, vertical thickness, of Sherwood Sandstone. This is he lower and major reservoir of the Wytch Farm Oilfield. It entered the Triassic sandstone from a subsea depth of 1738 metres, that is quite deep, deeper than at Wytch Farm. The highest 9 metres of the Sherwood Sandstone was shaley, not suprising since it is just beneath the argillaceous Mercia Mudstone.

A good porous sand was encountered not far down in the sandstone at 1748-1754 metres depth. There may be gas or oil, but there no oil shows were found. Because of a technical point with the seismic interpretation, the borehole seems not to have entered the Sherwood Sandstone at the level intended. This problem arose because the seismic velocity in the Chalk in the Harry Rocks area was higher than expected. Perhaps this was because of the hard, well-cemented Chalk, known to be present beneath the Ballard Down Fault, but I do not know the details. The result of this problem is the top of the Sherwood Sandstone proved to be 40 metres deeper than expected. Presumably the borehole was not, therefore, in the best and intended position.

With regard to reservoir potential, the Sherwood Sandstone did not have the good fluvial (river) channel sands, as are present at Wytch Farm. These have particularly good porosity and permeability features. The authors of the report thought that the area is off the main Sherwood sand channel axis. Thus the well was plugged and abandoned.

With regard to details, there was a good quality, 6 metre, hydrocarbon-bearing sand at the top of Zone 30, the top production zone of the Sherwood Sandstone at Wytch Farm. Below this there are a series of thin, individual hydrocarbon-bearing sands. This sequence, with natural gas, extends to the total depth of the borehole. This depth was at 44 metres below the mapped spill point, the theoretical base of the oil. The thin sand bodies are probably individually stratigraphically trapped or effectively closed off. However, if they are linked together and part of a connected reservoir body there is a question of how the structure would be sealed (from leakage of oil). A linkage or connection of faults would apparently be needed to seal the structure down to at least 1800 metres subsea. This is below the oil-water level in Licence Block 98/11-1 to the east.

For more detailed information there is a report [not seen]:
Watts, G. 2000. Old Harry Review: Review of results from Exploration Well L98/06-M18 and L98/06-M18Z in 98/11. By Giles Watts, June 2000. Internal Report of BP?

MISCELLANEOUS:

Natural History

With regard to miscellaneous items of natural history, sea campion (Caryophyllaceae - Pink Family) was pointed out to me by a member of the Open University Geological Society on the chalky meadow alongside the path from Studland to Harry Rocks. It was odd that this short-stemmed, cliff species of campion was still in flower on the 29 November 2003. The weather this year had been unusual (global warming?) with an exceptionally dry summer followed by a very mild October and a mild and wet November with no significant frost on the south coast. The wood near Harry Rocks used to be full of bluebells in the spring and probably still is.

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ACKNOWLEDGEMENTS

Alan Holiday, the well-known Dorset geologist and geological photographer has taken splendid photographs of the Ballard Down Fault and Old Harry Rocks cliffs. Some of his photographs are reproduced here with his permission. His help is very much appreciated.
I am very grateful to the Geologists' Association for permission to reproduce the photograph of Rowe and to Dr C.A. Boulter for permission to reproduce his photographs taken from the Waverley paddle steamer (note that dates on these photographs are dates of printing, not dates when taken which was shortly before). Alan Holiday has very kindly taken very good photographs of the Chalk Cliffs in the Harry Rocks and Ballard Fault area, and the opportunity to use of some of these is very much appreciated. I am very grateful to Sheila Alderman for organising an Open University Geological Society field trip to Studland and Harry Rocks. I much appreciate helpful discussion from John Chaffey, author of geographical and guides books on the region. Some photographs have been taken on a boat cruise kindly arranged by the members of the Probus society of Mudeford, to whom I am very grateful. I am very much obliged to the Director and staff of the Channel Coastal Observatory for permission to use their aerial photographs. This website could not be run in its present form without the long-standing support of the National Oceanography Centre, Southampton and the helpful cooperation of iSolutions, Southampton University. I much appreciate the advice and help of my daughter, Tonya Loades of Bartley West, Chartered Surveyors.

BIBLIOGRAPHY AND REFERENCES

Please go to the Bibliography of Geology of Studland and Harry Rocks area.

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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.
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