West, Ian M. 2016. Brownsea Island in Poole Harbour, Dorset; Geology of the Wessex Coast of Southern England. Internet site: www.southampton.ac.uk/~imw/Brownsea-Island-Geology.htm. Version: 4th December 2016.
Brownsea Island in Poole Harbour, Dorset, Geology of the Wessex Coast

by Dr. 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, with list of webpages | |Bournemouth Cliffs| Harry Rocks, Ballard Point| Sandbanks Sand Spit| Studland, South Haven Peninsula| Studland, Tertiary Strata| Studland, Poole Harbour Side of the Peninsula| Swanage Bay|

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Selected external link: The National Trust.

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The entrance to Poole Harbour at Sandbanks and Studland, Dorset, with Brownsea Island, aerial view by Alan Holiday, June 2011

Poole Harbour, aerial view from above Wareham, looking eastward to Brownsea Island and beyond

The eastern part of Brownsea Island, Poole Harbour, Dorset, UK, seen from a helicopter, 6th July 2013

A general view of most of Brownsea Island, Poole Harbour, Dorset, as seen from a helicopter looking southward, 6th July 2013, unlabelled version

Cliffs of Branksome Sand, Eocene, on the southeastern part of Brownsea Island, Poole Harbour, Dorset,UK, 2007

Erosion of the cliff of Branksome Sand Formation at the southeastern corner of Brownsea Island, Poole Harbour, Dorset, UK, as seen on the 16th November 2016

Branksome Sand Formation in the cliff in the southeastern part of Brownsea Island, Poole Harbour, Dorset,UK

Brownsea Island, in Poole Harbour, Dorset, seen from Constitution Hill viewpoint on a cold winter day

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Part 3: LOCATION - Brownsea Castle and Church Area

Part 4: LOCATION - Southeast Cliffs

Part 5: South Shore - Copperas Industry

Part 6: Southwest Pottery Area

Part 7: LOCATION-Pottery Pier and Maryland Areas

Part 8: LOCATION-Offshore of Brownsea Island Part 9: Wytch Farm Oilfield under Brownsea Island

10. Acknowledgements

Bibliography and References



Contact the A National Trust for detailed information about this island and details of access and charges. This beautiful and historic island is maintained and controlled by the National Trust with help from volunteers. It is open to visitor access courtesy of the National Trust.


Topographic Maps

Isle of Purbeck Location Map

Enlarged topographic map of Brownsea Island, Poole Harbour, Dorset, UK

The most suitable topographic map for Brownsea Island is the Ordnance Survey, Outdoor Leisure Sheet 15, Purbeck and South Dorset. Scale 1:25,000.

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Aerial Photographs

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

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

The eastern end of Brownsea Island, Poole Harbour, Dorset, in a 1857 map and a 2004 aerial photograph, courtesy of the Channel Coastal Observatory

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Geological Maps

Location and geology map, 1907

This is an old geological map from Woodward (1907).

A geological map of Brownsea Island, Poole Harbour, Dorset, UK, modified and with additions, after part of BGS map sheet 329

It is recommended to purchase the current geological map of the British Geological Survey. This is the Bournemouth Sheet, 329, Geological Map - 1:50,000 Solid and Drift Edition.

Melville and Freshney (1982) have provided a good brief and useful introduction to the region. Much more useful for serious study and technical details is Bristow, C.R., Freshney, E.C. and Penn, I.E. (1991). , which is strongly recommended for purchase from the British Geological Survey. It is a very good memoir, full of useful information.

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Access to Brownsea Island

See the The National Trust, owners of the Island for details. Check whether the island is open on a particular day. Note that usually the last ferry back is at about 5 pm but check whether this is the case for the day that you intend to visit.

See: Getting There - Brownsea Island, National Trust.

National Trust brochure and map received on arriving at Brownsea Island, Poole Harbour, Dorset, UK

Arriving at the quay of Brownsea Island, Poole Harbour, Dorset,UK

A Common Tern, Sterna hirundo, rests on a post at Brownsea Island, Poole Harbour, Dorset,UK, May 2008

A large fish in the clear water of Poole Harbour at the western end of Brownsea Island, Dorset, UK

Brownsea Island, which The National Trust, is most easily reached by taking a ferry either from the end of the Sandbanks Peninsula or from Poole Quay. The Sandbanks crossing is shorter, although it can be difficult to find places to park at times. In summer the ferries depart at about every half an hour. The last ferry usually leaves from the island at 5pm, but check the times when you take the ferry out (or obtain details from the The National Trust).

Note that you have to pay the ferry fare and then when you arrive at Brownsea Island you pay an entry fee, unless you are a member of the The National Trust. It is an interesting place in many respects and well-worth the payment. Note that the castle is not open to the public but the island is an excellent place to explore.

On arrival by ferry, the Tudor castle, formerly protecting the entrance to Poole Harbour, is seen as a dominant feature. It is now owned by the John Lewis organisation, and used for company holiday. At the landing stage you are welcomed by National Trust staff and toilets and other facilities here. Try to obtain a map of the island because you will need one once you have left the main facilities.

A Peacock wanders on Brownsea Island, Poole Harbour, Dorset,UK, May 2008

From here you walk westward on the main path, passing a bird observatory. Soon you are on grassy lawns with peacocks and chickens running free, and with pine forest around. The path continues on westward but with various branches. The areas of geological interest are mainly on the south coast, and after a stretch of walking you will find a small branching path to this area. You can then explore various parts of the coast and forest. Few people will be seen and it does give a feeling of exploration on a small scale. Although actually very close to Poole and Sandbanks it seems as though it is quite a remote place.

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General Aspects

Branksea Castle  photographed from Sandbanks, 2002

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

Brownsea Island is the largest and most interesting island in Poole Harbour. It is a former hill standing above river valleys when sea-level was lower, and separated as an island when flooding took place during the Flandrian Transgression after the Pleistocene Ice Age, and Poole Harbour was formed.

In the 16th century it was first of significance as a defencive area at the entrance to Poole Harbour. Soon it became important for mineral workings and processing (see Copperas below). Later it was a private island, a type of stately home and park, but with a pottery industry at the eastern end. It had no public access and has retained an almost 19th century character. It became famous for the initation of the Baden-Powell Scout Camps. Relatively recently it has been taken over by the National Trust. More detail on the history is given below.

The red squirel, Sciurus vulgaris on a pine tree on Brownsea Island, Poole Harbour, Dorset, UK

As you walk through the woods look out for the red squirrel, Sciurus vulgaris. Elsewhere in Dorset has been replaced by its larger, tougher and more confident, American relative, the grey squirrel. The grey species has not managed to get on to the island.

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A Brief Summarised History of the Island

(this is not a complete list of owners and not detailed, see the literature given in the reference list for more information. This is merely background to the geological description of the island.)

1015: The first incident of note recorded concerning the Island is that Canute landed upon it. Canutus having spoiled the church and monastery of Cerne, took the haven and sailed thence to Branksea. His force, being laden with the spoils of the monastery, doubtless found the little island a safe retreat. Here they could, without fear of molestation, mature plans for further marauding expeditions. The above event is placed A.D. 1015. (Bennett, 1881)

1154: King Henry II granted to the Abbot of Cerne the right of wreck on the Island. Leland says - " the Island had in it "no building save a chapel only, for an hermit, it longeth to Cerne Abbey." The chapel was dedicated to St. Andrew. (Bennett, 1881)

1540: Henry VIII built a substantial blockhouse with a moat. The king granted the Island, and the water surrounding it, to John, Earl of Oxford.

In the 9th year of the reign of James 1. this Island and the bill or town of Poole, late the possessions of Charles Brook, were granted to Robert, Earl of Salisbury.

In the reign of Charles II it belonged to Sir Robert Clayton.

1726: It was purchased about 1726 for 300 pounds, by 'Villiam Benson, Esq., auditor of the imprest, and known as "Mad" Benson. There were tales of Black Magic on the island.

1762: The Island was conveyed to Sir Gerard Napier and Humphrey Sturt, Esq., to the last of whom, upon the death of the former, the whole property devolved.

Lady Albinia Foster held the island before the Waughs.

1852: Colonel Waugh and his wife Mary Petrie Waugh bought Brownsea Island. They initiated the pottery industry. They left the island in 1855 leaving 665,000 pounds in dept.

1870: Lord Eversley, Secretary of the Admiralty, inspected Brownsea Island, then up for sale, with a view to building the Naval College here. In the end it was built at Dartmouth.

A view of Brownsea Island, Poole Harbour, Dorset, in 1881, modified from an etching in Bennett

1871-1891: Rt. Hon. George Augustus Cavendish Bentinck, M.P. for Whitehaven, owned the island. He tried to revive the pottery with little success. He brough Italian and Venetian items to the island. (Moore, 2003).

1891: Major Kenneth Robert Balfour owned the island. He established a peat-cutting industry. Large quantities were cut and transported to London. It was sold in its natural state to Charlton Xavier Hall who lived on neighbouring Green Island (Battrick, 1978). The peat has not been mapped on the island on the British Geological Survey maps (either old or new edition). Where were the deposits? There is a very small amount of peaty ground on the beach of the South Shore but no substantial deposits are obvious. A much more likely area is low ground in and around St. Andrew's Bay. It would expected in alluvium near sea-level. Peat excavations would now be ponds or lakes.

1901: Charles and Florence van Raalte, with great wealth from cigar manufacturing in Holland, bought the island as a country estate. A 9 - hole golf course was established; there was much shooting, with 2000 pheasants bred each year. Most new male employees had to be musicians and were required to play in the Estate Band. Mr. van Raalte employed 71 servants and workers including a professional golfer and 12 crew members for his two steam yachts. He kept a four-in-hand carriage at Sandbanks. Baden-Powell held his camp on the island while it was owned by the van Raltes. See Moore (2003).

1907: Baden-Powell first scout camp took place on Brownsea Island. More details are given below. The van Raaltes still owned the island at this date. See more details below regarding this event.

1925: Sir Arthur Wheeler, a wealthy stockbroker bought the island for 60,000 pounds. He planned to use the Castle as a hotel and to flood St. Andrew's Bay, then still reclaimed pastureland (Moore, 2003).

1927: Mrs Mary Florence Bonham-Christie bought the island and became an eccentric recluse. The former inhabitants were sent off the island. People landing on the shore were thrown into the sea. The keeper fired blanks over the heads of people approaching in boats. Mrs Bonham-Christie was totally opposed to all forms of blood sport, animals in captivity and performing animals Battrick (1978) . She was, however, so extreme that even bait digging for worms was banned. The island became wild and overgrown. Mrs Bonham-Carter was remarkably successful in creating one of the most heavily-populated bird and animal sanctuaries in Britain. The present fame of the island as a nature reserve and a National Trust visitor site is partly dependent on Mrs Bonham-Carter's absolute conservation in the past.

For much more information see the booklet: Moore, P. 2003. For Nature not Humans - Recollections of Brownsea Island under the Ownership of Mrs Bonham-Christie.

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History continued - Baden-Powell and the Scout Camp -1907

A Scouts' Signpost at the official Scouts' Campsite on Brownsea Island, Poole Harbour, Dorset, UK, 2008

The southwest corner of Brownsea Island, Poole Harbour, Dorset, UK

Here is the southwestern corner of Brownsea Island, about 200 metres beyond the original Scout Camp Site of Baden Powell. The great Scout Movement started here. Even now the area seems suprisingly remote for a place so close to the town of Poole and the urban development of Bournemouth. The south and southwestern coast of the island gives a good view southward or southwestward across part of Poole Harbour. The Purbeck Hills stand out as a ridge of nearly vertical Chalk. It can be seen why this area was chosen for the trial Scout camp that was to be start of the Scout movement.

The Brownsea Island Scout camp was a boys camping event on Brownsea Island in 1907. It was organised by the famous soldier of Mafeking, Lieutenant-General Baden-Powell to test his ideas for his book "Scouting for Boys: Handbook for Instruction in Good Citizenship". Important guidance on personal character and the outdoor life is given. In addition there are some aspects of the book which seem very strange now, but undoubtedly reflect the culture of the time. Some examples are shown below.

Lieutenant General (later Lord) Baden-Powell was said to be a "little man with large freckles, a bony nose and thinning hair, a sandy-coloured moustache and twinkling blue eyes" (Battrick, 1978). With his friend, Major Kenneth McLaren, he set up the camp above the south shore of the island under a flagstaff flying a Union Jack. Mrs van Raalte had given permission in the absence of her husband. The van Raaltes had offered the experimental campsite after meeting Baden-Powell when he was on holiday in Ireland (Battrick, 1978).

Twenty boys from different social backgrounds participated from 1 August to 8 August 1907 in activities around camping, observation, woodcraft, chivalry, lifesaving and patriotism. Recognised as the world's first Scout camp, the event is regarded as the real origin of the worldwide Scout movement. This great youth activity started as a very small camping event here on the southern part of the island.

Up to the early 1930s, camping by Boy Scouts continued on Brownsea Island. In 1963, a formal 50-acre (200,000 square metre) Scout campsite was opened by Olave Baden-Powell, when the island became a nature conservation area owned by the National Trust. The camp site was at the same place on southern side of the Island and the location is still used for modern scouting activities.

The booklet shown below provides a good brief account of Baden-Powell and the Brownsea camp site, with some excellent old photographs of Baden-Powell (in his trilby not scouting hat).

Booklet on the history of the Scout movement on Brownsea Island, Poole Harbour, Dorset, UK

Baden-Powell, Scouting for Boys, extract shown in relation to the original camp site on Brownsea Island, Poole Harbour, Dorset, UK

A strange extract regarding hats from Baden-Powell, Scouting for Boys

In the 1950s, Donald Payne (1953) met the boatman Bill Harvey, who took Baden-Powell and his boys across to Brownsea Island (we still travel there by Harvey Boats). Here, for interest, is an extract from Payne's record of the meeting [pp. 29-30]:

"It was on Captain Horn's [the Poole Harbourmaster] advice that I called next on Bill Harvey, whom I found outside his home in West Quay Road [Poole]. Thick-set, ruddy-cheeked and getting on for eighty, he told me that his father had been in charge of the boats used by Marconi for his experiments at Sandbanks. He himself did not remember Marconi well. "He were a quiet little chap," was all he would say; "didn't like to be disturbed, and us Poole men thought nowt o' him." ... [continues re Marconi at Sandbanks]

Bill Harvey also told me about Lord Baden-Powell, for it was in his motor launch Hyacinth that Bill took a party of twenty boys across to Brownsea Island, where, in 1907, they held the first experimental Scout camp. "I didn't heed them much," said Bill, who seemed to have a genius for taking historic events in his stride, "they was just a crowd o' trippers to me."

But his launch Hyacinth, and the woods of Brownsea Island, played their part in helping to establish an institution whose power for good in the world is quite impossible to estimate. Had the camp been a failure Baden-Powell's dream of world-wide Scout Movement might never have been realised. But the camp under his inspired leadership, was never likely to fail. Twenty boys were chosen for the experiment; some were the sons of Baden-Powell's friends, others the the sons of Poole tradesmen; and so great was their enthusiasm that the camp's duration was extended from a week to twelve days - from July 28th to August 8th.

Baden-Powell, in a letter written to each of the boys parents, listed his objectives as "to teach woodcraft, observation, discipline, health and endurance, chivalry, saving life and patriotism." Local fishermen as they paid out offshore seine nets, may have thought it odd to see the hero of Mafeking, in shorts and a trilby hat, imitating bird calls or ..............; but none the less was history in the making, and had Baden-Powell not spent his twelve days on Brownsea Island we would to-day be so much the poorer..."

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In Poole Harbour northwest of the Studland or South Haven Peninsula is Brownsea Island. It consists of Eocene strata of the Bracklesham Group and includes a small areas of the Parkstone Clay of the Poole Formation but is mostly of Branksome Sand (British Geological Survey map, Bournemouth Sheet, 329, Solid and Drift Edition; Bristow, Freshney and Penn, 1991). It is notable for being on the synclinal axis of the Hampshire Basin and beneath it lies part of the Wytch Farm Oilfield (the Sherwood Reservoir). Some Pleistocene gravel terraces (Terrace 6 and 8) are present as relatively thin spreads of gravel.

On a map of 1857 (Battrick and Lawson, 1978) the southwestern low terrace of the island, just south of the old cliff line, is referred to as "Dark or Allum Clay District". At the western end of the island between the New Pier and the Old Pier is a small area of "Gravel and Allum Clay". It is at the foot of the forested bank near the old mess room and workshops. There are other brickpits, claypits and shafts but alum or copperas is not mentioned elsewhere on the map.

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A chart showing lithostratigraphic schemes for the Palaeogene strata of the Bournemouth and Poole area, including Brownsea Island and Barton-on-Sea

The Palaeogene sequence of strata in the Bournemouth-Poole area, Dorset, UK, modified after Bristow et al.

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2 - STRATIGRAPHY continued:

The Parkstone Clay - Introduction

The Parkstone Clay of Eocene age on the coast of Brownsea Island, Poole Harbour, Dorset, UK, May 2008

Stems of plants, preserved in the Parkstone Clay, Poole Formation, Brownsea Island, Poole Harbour, Dorset, UK

The hot, wet, forest and delta-swamp palaeoenvironments in which the Bournemouth leaf beds of the Eocene originated (reconstructions, based partly on Webster Smith ,1931),

Underlying much of area around Poole Harbour is the Poole Formation. It formed in or around the Poole Delta about 45 million years ago when the climate was subtropical here, although only at a palaeolatitude of about 40 degrees north.

This Eocene unit was formerly known as the Pipe Clay Series, and was part of the Bagshot Beds (an old name, not in use now). The Poole Formation is about 160 metres thick. The uppermost part of the Poole Formation is a clay, the Parkstone Clay Member. This is of Bracklesham age from near the middle part of the Eocene. The Parkstone Clay is only 7 metres thick on Brownsea Island, although elsewhere in the region it can reach 14m or 22m Bristow, Freshney and Penn (1991). The reduced thickness on Brownsea Island may be due to downcutting by the erosional base of the Branksome Sand. The Parkstone Clay is well-exposed in the southern cliffs of Brownsea Island.

Although there is little doubt that, in general terms, the Parkstone Clay is Bracklesham in age, its exact position within the Eocene is not so well-established because of general lack of marine fossils. It may be Lutetian (perhaps Upper Lutetian or Auversian) in age. Its facies is like that of the laminated carbonaceous clays of the Marsh Farm Formation (Bracklesham Group) of the Southampton Area (Edwards and Freshney, 1987). The dinoflagellate cyst Kisselovia cf. coleothrypta was recovered from the Parkstone Clay.

In terms of lithology the Parkstone Clay is a is is a brown silty, slightly carbonaceous clay. Although it is structureless in part, it is often shows lamination, and this is very noticeable in the cliffs of Brownsea Island. The clay is quite sandy and silty. It contains impersistent sand layers ranging from 0.5mm to several millimetres thick Bristow, Freshney and Penn (1991). Scattered beds of fine-grained sand up to 8cm thick also occur. Laminations and thin beds of sand more common towards the base. Clay layers have sharply defined tops and bottoms. Much of the Parkstone Clay is quite dark in colour because of a content of lignite (plant material) and and pyrite. In places in the Poole area there are much lighter-coloured beds of pipe clay or ball clay. This can be light grey and seem almost white by comparison with dark grey clay. The pipe clay or ball clay can be of economic importance for the manufacture of pottery.

On Brownsea Island the Parkstone Clay that is exposed in the cliffs is mostly dark grey and carbonaceous. White pipe clay does not seem to be exposed at present, even if it is present at all above sea-level. The dark grey type of Parkstone Clay is well seen in the low cliffs on the south side of Brownsea Island. Examined in detail this can be seen to be a dark, very pyritic and carbonaceous clay with sand laminae in places. It contains many plant fragments and some tree trunks in lignitic form. Fossil leaves have also been found in these strata.

The weathering of the pyrite content is responsible for the development of encrustations of sulphate minerals discussed below. The sulphate rich waters give off an acidic odour like that of sulphuric acid.

Many sections on Brownsea Island expose the junction of the Parkstone Clay and the overlying Branksome Sand. This is easily seen and often abrupt. In some place, though, it rather transitional with a progressive increase in sand.

The heterolithic Parkstone Clay of the Poole Formation on Brownsea Island, Poole Harbour, Dorset,UK, showing sand linsen

The clay breaks off in layers giving a shaley appearance, except that it is quite soft and poorly consolidated. The laminated character results from sand linsen which occur in a clearly heterolithic sequence. It probably originated on tidal flats in the Eocene delta or estuary. A somewhat restricted environment with freshwater inflow accounts for the lack of typical marine fossils. It also accounts for the lignitic plant content.

Bristow, Freshney and Penn (1991) recorded the following westernmost section at map reference SZ 0104 8798.

Pleistocene river gravel - 1 to 2m.

Branksome Sand

Sand, medium to very coarse grained, tabular bedded on a decimetre scale. About 3m. from the top there is a 0.1m thick brown silty clay underlain by a grit band. Total thickness present - c 5.0m.

Poole Formation - Parkstone Clay

Clay, brown silty, slightly carbonaceous, structureless in part, but also with common lamination. Impersistent sand layers ranging from 0.5mm to several millimetres thick. Scattered beds of fine-grained sand up to 8cm thick also occur. Laminations and thin beds of sand more common towards the base. Clay layers have sharply defined tops and bottoms.

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2 - STRATIGRAPHY continued:

The Parkstone Clay - Pipe Clay or Ball Clay

The Seymour mining area for pipe clay or ball clay on the northern part of Brownsea Island, Poole Harbour, Dorset, UK, based on part of an old map from 1857

The former mining area of Seymour, northern part of Brownsea Island, Poole Harbour, Dorset,UK, seen in an aerial photograph of 2004, courtesy of the Channel Coastal Observatory

Fossil leaves from the Pipe Clay Series of the Poole Formation, Poole Harbour and Purbeck area, Dorset

Light grey to white Pipe Clay or Ball Clay is more important because it can be used for pottery. This is present underneath the grey clay and fairly deep under most of Brownsea Island. The main mining area for this is the Seymour district in the north of the island as shown in the map and photograph above.

In the mid 19th century Colonel Waugh, the owner of Brownsea Island hoped to make hugh financial returns from the economic resources of the Parkstone clay. Finding good pipe clay or pottery clay was part of the plans of this enterprise.

The pipe clay or ball clay is not well seen (if at all) at the surface but was expected beneath the grey clay. There are two borehole indicated on the 1857 map of the Island and perhaps it was discovered in these. Mines was dug in the northern part of the Island in the Seymouth area. Pipe clay or ball clay mining took place actually under Poole Harbour (White, 1917) in the north adit shown on the map above (Battrick and Lawson, 1978). Fossil leaves were found in it.

There is a strange story about the finding of the pipe clay. It seems doubtful as to whether good white ppipe clay was exposed anywhere at the surface of the iIsland, but it is not impossible. Most of the Parkstone Clay at the surface is not pipe clay but is grey lignitic clay; the mine shafts for ball clay went down 63 feet before adits were driven off north and south. Geologists, though, who had studied the local area in detail would know that pipe clay does occur beneath the grey clay (upper part of the Parkstone Clay) at Parkstone, just across the water.

"Then, as they walked round the estate, Mary Waugh, who was by the way an amateur geologist, happening to look at the ferrule of her umbrella, told her husband that she thought there must be china clay just below the surface. Colonel Waugh was a director of the London and Eastern Bank in London and immediately saw the possibility of exploiting such a find - if such it was." (Battrick, 1978)

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2 - STRATIGRAPHY-continued:

The Branksome Sand Formation (Eocene)

Branksome Sand Formation in the cliff in the southeastern part of Brownsea Island, Poole Harbour, Dorset, UK, 2007

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2 - STRATIGRAPHY continued:

Pleistocene Flint Gravels

Pleistocene flint gravel of terrace 8 in the southeastern cliffs of Brownsea Island, Poole Harbour, Dorset, UK

Pleistocene river gravel - 1 to 2m. of brown flint gravel is present on the top of the island. This is a river gravel formed in periglacial conditions. It is similar to the river gravel deposits that occur at the cliff tops of Bournemouth and Barton coasts. Two terraces are present. Terrace 6 outcrops roughly east-west along the northern part of Brownsea Island. Terrace 8 occupies the east-west plateau on the southern part. These two terrace gravels are quite old Pleistocene river valley deposits, formed when sea-level was higher. The river channels have subsequently cut down and left these isolated patches on was once the hill of Brownsea. Higher and older gravel terraces, particularly numbers 10, 11 and 12 are present at Bournemouth. The cliffs there are largely in 9 and 10, although there is a small patch of 8, like that of southern Brownsea, at Flag Head Chine, northeast of Sandbanks.

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2 - STRATIGRAPHY continued:

Brownsea Island in the Late Pleistocene

It is of interest to consider the Quaternary history of the island. This can be deduced to some extent from the Pleistocene gravel deposits of the region and the evidence of old river channels cut below the present sea-level (West, 1980). During the late part of the Pleistocene Ice Age, the Devensian, round about 100 thousand years ago the sea-level was about 140 m lower than at present and the English Channel was dry. At that time the local rivers such as the Frome and the Piddle were just the upper reaches of a major English Channel river system that fed into an extension of the River Seine off the French Coast (northwest of Le Havre). The main river in the local region was the Solent River which collecting the Frome, the Piddle, the Stour, the Avon and other minor streams extended eastward around the northern part of the Isle of Wight. This river then swung south and southwestward around the eastern end of the Isle of Wight to head for the extended Seine.

Poole Harbour, Poole Bay etc were areas of dry land and Brownsea Island at this time was a hill about 50m in height above the valley floor. It had rivers or streams on both sides and thus it resembled in some respects St. Catherine's Hill near Christchurch, which lies between the Stour and the Avon. On the north side was the deeper and larger river valley which later was to become the main channel of Poole Harbour. The river flowing here was probably originally connected to the Solent River system but at some time in the late Pleistocene it was captured by a south-flowing river in what is now Poole Bay and this river crossed the Chalk ridge.

Finally, about 10 thousand years ago, the ice began to melt and sea-level rose. The formerly dry English Channel was now flooded in the Flandrian Transgression. More recently, 5 or 6 thousand years ago, Poole Harbour began to form by flooding of the valley systems. Perhaps only a few thousand years ago the seawater finally flooded the shallow area between Brownsea and the Isle of Purbeck separating it as an island.

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Branksea Castle, Brownsea Island, Poole Harbour, Dorset, UK, 2010

The Castle is situated at the westernmost part of the Island at the junction of the Parkstone Clay outcrop (to the south) and the Holocene shingle deposits of the spit which extends northwards and partly encloses St. Andrew's Bay. The castle has been extended and enlarged by various owners of the island and the original small castle of King Henry VIII is concealed within it.

The marble well-head or pozzo used as a monument to Major General Lord Cavendish-Bentinck, who owned Brownsea Island, Poole Harbour, Dorset, from 1871-1891

This is the well head which marks the burial site of George Augustus Cavendish Bentinck and his wife. It is of Italian marble, a pozzo of great antiquarian value, bearing the crest of the Leza family, and dating back to 1497 (Battrick, 1978). The pink marble was polished and the iron work repainted annually for many years after the death of Cavendish-Bentinck. However, it is in poor condition now.

Pink nodular limestone or marble in the Cavendish-Bentinck Pozzo, Brownsea Island, Poole Harbour, Dorset, UK, 2010

The well-head has a superficial appearance of slightly weathered, grey limestone. In fact, as shown in the photograph above, is a nodular pink marble or hard, non-porous limestone, perhaps originally a polished griotte.

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The southeastern cliffs of Brownsea Island, Poole Harbour, Dorset,  UK, from the sea, 20th June 2010

Sea defence posts near Harry Point and at the southeastern cliffs of Brownsea Island, Poole Harbour, Dorset, are sloping because cliff debris has fallen behind them, 2010

Failing sea defences just west of the Harry Point cliffs, Brownsea Island, Poole Harbour, Dorset, UK, June 2010

Ground and aerial view of the cliffs at the southeastern part of Brownsea Island, Poole Harbour, Dorset,UK

A view down the southeast cliffs of Branksome Sand at Brownsea Island, Poole Harbour, Dorset, UK, June 2010

Cross-bedded Branksome Sand Formation in the clifftop, and under Pleistocene gravel, in the southeastern part of Brownsea Island, Poole Harbour, Dorset,UK

Branksome Sand Formation, seen undergoing eroded at the southeastern end Brownsea Island, Poole Harbour, Dorset,UK, May 2008

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- Jarosite of the Parkstone Clay

Jarosite - the sulphate mineral of Mars - Spectroscopy.
"The goal of this thesis is to characterize and interpret the spectroscopic characteristics of the alunite mineral group, with emphasis on the Fe3+-bearing jarosite species within this group such as jarosite, KFe3(SO4)2(OH)6. The alunitejarosite group was chosen to be the main focus of this thesis because of its recent “discovery’ based on interpretation of the Mössbauer data from the Mars Exploration Rovers (Klingelhöfer et al., 2004). This result was exciting because jarosite only forms in the presence of water. If it is possible to confirm that the mineral identified is indeed jarosite, it can then be concluded that there was water on the surface of Mars when the rocks formed. This would be very important because one of the main goals of the mission to Mars was to try to confirm if there ever had been water present on the Martian surface. On Earth, jarosite forms in one of four different types of occurrences. The first is in oxidized sulfate sections of ore deposits or in pyrite-rich rocks such as coal. In these parageneses, jarosite often forms as a coating on the other Fe sulfate minerals. The second is in clays, either as small, hard lumps called nodules or spread diffusely through other clay minerals. This is thought to occur because the oxidation of the pyrite contained in the clay provides the iron and sulfate, while the acid is drawn out of the clay and provides the alkalis. The third occurrence is in acid soils, where the molecules that make up the soil are either able to give a hydrogen ion or want to accept a pair of electrons. Acidic substances have a pH level, which is a measure of the hydrogen-ion concentration, of less than 7. There are many places around the world where the soil has a pH of 3 or 4; when this occurs in marine sediments, it is then likely that the soil also contains pyrite, resulting in a yellow soil (Warshaw 1956). The fourth is in hydrothermal deposits, where jarosite is a hypogene mineral, meaning it is formed under or found below the earth´s surface. Examples of this are found at hotspring deposits in Yellowstone National Park (Allen and Day 1935) and in Japan (Kinoshitea et al., 1955, Saito, 1962), as well as Indonesia (Zelenov and Tkachenko 1970)."

(Extract from: Rothstein, Y. 2006. Spectroscopy of Jarosite Minerals, and Implications for the Mineralogy of Mars. By Yarrow Rothstein. Mount Holyoke College. Thesis available online as a PDF file.)

Cliffs of the southern coast of Brownsea Island, Poole Harbour, Dorset,UK, with the Jarosite Bed in the Parkstone Clay, March 2007

The Jarosite Bed in the Parkstone Clay, Eocene, on Brownsea Island, Poole Harbour, Dorset, an investigation with members of the Poole Harbour Heritage Project, PHHP, March 2007

A close-up view of jarosite encrustions on dark grey, pyritic, sandy clay of the Parkstone Clay Formation, Eocene, of Brownsea Island, Poole Harbour, Dorset,UK

An enlarged macro photograph of jarosite from the Parkstone Clay, Brownsea Island, Poole Harbour, Dorset,UK, by David Cousins, 2007

Use in the 11th Century of what was probably jarosite :
"The yellow and dark sorts of alum are called 'bird-dropping alum'; these are not used in pharmacy but are only suitable for the plating of metals. When they are added to processed copper (powder), being made into a paste with crude vinegar and smeared on the surface of iron, the iron is all turned to the colour of copper. But although the outside colour becomes coppery the material inside remains quite unchanged."
Ching-Shih Cheng Lei Pei-Chi Pen Tshoa (the Classified and Consolidated Armamentarium of Pharmaceutical Natural History, 1083). Translation from the Chinese language quoted by Osborne (1999).

The Parkstone Clay is very pyritic in part, especially where it is very dark in colour, and has some well-developed incrustations of yellow jarosite on a certain bed. Jarosite is a common efflorescent mineral that occurs on the surface of pyritic and parts of the Parkstone Clay. Jarosite, elsewhere, has sometimes been wrongly referred as "sulphur" because of its bright yellow appearance but, in fact, it is an iron-bearing sulphate, not sulphur.

Jarosite is the yellow colouring matter in alum shales and alum clays. It is not true alum, which is a white substance, containing aluminium. Jarosite has no Al content only Fe and some other cations. However, like alum, it is a sulphate and the shales or clays in which it occurs can be converted by the correct processes into true alum.

The most pyritic parts of the Parkstone Clay are usually lignitic because the pyrite owes its origin in Eocene times to sulphate-reducing bacteria in the presence of organic matter, which in this case was plant debris.

The mineral jarosite is a hydrated sulphate of iron with either potassium (most common), sodium (natrojarosite) or ammonium (ammoniojarosite). It is an iron analogue of alunite. The formulae of the varieties of jarosite are given as follows:

KFe 3+ 3 (SO 4 ) 2 (OH) 6

NaFe 3+ 3 (SO 4 ) 2 (OH) 6

(NH 4 )Fe 3+ 3 (SO 4 ) 2 (OH) 6

This mineral is normally present as sulphur-like, irregular surface layer or efflorescence of small yellow crystals. The efflorescence is temporary because the mineral is slowly soluble and can be physically washed off by heavy rain or by waves. If it is removed it tends to develop again in favourable weather conditions which probably involve some rain, some oxidation of pyrite and then some evaporation of the surface water film. Without chemical analysis and/or X-ray diffraction it would not easily be possible to identify the variety of jarosite (it is not all K-jarosite in the Wessex coast region). The original jarosite was from Barranco Jaroso in the Sierra Almagrera, near Aquilas in Murcia, Spain ( Ford (1938)).

Mineralogical data on jarosite (potassium jarosite)
(partly from Dana (1932).)
Colour - ochre yellow, yellowish-brown or clove-brown; streak - light yellow,shining; lustre - vitreous to subadamantine, brilliant also dull; diaphaniety - translucent; SG - 3.15-3.26, H - 2.5 - 3.5; cleavage (0001) distinct to good, brittle; fracture - conchoidal to uneven; crystal system - trigonal; c-axis - 1.2492; 10bar11 to bar1101 angle - 90°, 45 minutes; 0001 to 10bar11 angle - 55°, 16 minutes; optical - omega [ordinary ray] = 1.820, epsilon [extraordinary ray] = 1.715 [therefore the ordinary ray is slow and the extraordinary ray is fast. With epsilon < omega the crystal is negative].
The world's best specimens come from Pena Blanca uranium mine, near Aldama, Chihuahua, Mexico; large crystals occur at Tombstone, Arizona, It occurs at Chuquicamata, Chile; tabular crystals come from Horni Slavkov, Czech Republic. In Britain it is very common as an efflorescence on pyritic clays and shales. It occurs on Wealden strata near Lulworth Cove and elsewhere, on Eocene clays at Bournemouth, Barton-on-Sea, Hordle Cliff etc. It is very common on Carboniferous strata, particularly Coal Measures (where it has been referred to in the past as "sulphur"), as at Meal Bank Quarry, Ingleton and many other places.

The jarosite and associated melanterite, discussed below, and the pyrite from which they are derived have been noticed long ago, although not, of course, understood as at present.

Here, for interest, is an account of the pyritic Parkstone Clay from a Victorian guide book to Poole and Brownsea Island by Brannon.

"Near these [pottery] works [on the south coast of Brownsea Island] are the best illlustrations of the extraordinary proportion of the sulphates of iron, alumina and lime in the clays of the Poole basin or trough. Not only is the greatest portion of the upper bed of clay, to at least thirty feet [approx. 10m.] in thickness, replete with ordinary iron pyrites in every variety of form (termed bv the workmen "mundic"}, but in one place is a vein of considerable thickness of native crystallised sulphate of iron or copperas and so great is the proportion of alum [actually the iron-bearing sulphate - jarosite, not the aluminium-bearing sulphate alum?]; that it not only effloresces but 'forms on the exposed surfaces thick incrustations which constantly peel off to give place to fresh layers and lie in considerable quantities on the surface of the debris at the foot of the bank. The acicular crystals of selenite, too, glitter in the sun at all points, and at some parts the efflorescence has almost the aspect of pure sulphur from its bright yellow tinge" [as seen in the photographs above].

(Dr William Sheldrick kindly drew my attention to this description)

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5 - LOCATION - SOUTH SHORE continued -

Copperas or Melanterite Encrustations

Alum and copperas were once important on Brownsea Island. The following extract is from the Brownsea Geology Trail Leaflet produced by National Trust and available from the National Trust Office on Brownsea Island. (The paragraph was reproduced in the Digs Digest, DIGS - "Dorset's Important Geological/Geomorphological Sites", Issue No. 6, July, 2000)

"Copperas is the old name for hydrated ferrous sulphate - a green compound, the colour of which probably explains the name "copperas" by the association of a green colour with weathering products of copper (verdigris). It was used as a mordant (colour fixer) in the dyeing industry, for tanning and in the manufacture of ink and the pigment Prussian Blue. There are records of Brownsea copperas being shipped from Poole to London by the bark 'Bountiful Gift' in 1589." The copperas (ferrous sulphate: FeSO4+7H2O), "iron vitreol" or melanterite, as it is known in mineralogical texts, results from the oxidation of pyrite in the Eocene strata and was common in the Bournemouth cliffs as at Alum Chine.

A macro photograph of copperas or melanterite crystals on the Parkstone Clay, Eocene, at Brownsea Island, Poole Harbour, Dorset,UK

A sulphate encrustation showing some type of transition from melanterite, upper part, to jarosite, lower part, on the Parkstone Clay, Eocene, Brownsea Island, Poole Harbour, Dorset,UK

Copperas is an old name for the iron sulphate, melanterite, FeSO 4 .7H 2 O , a monoclinic, green to white, soluble mineral occurring as encrustations on weathered pyritic or pyritic rocks. It is often associated with jarosite. Where it occurs you can often smell the acid and metallic environment. Plants may be killed by the acid water. It is present naturally on pyritic Parkstone Clay on Brownsea Island. Originally in historic times it was probably collected from the cliffs here, at Bournemouth and other places in Poole and Christchurch Bay where it is common on Eocene strata.

Footnote:Mineralogical Data on Melanterite
(partly from Dana (1932).)
Monoclinic. Usually capillary, fibrous, stalactitic, and concretionary; also massive, pulverulent. Cleavage: c(OOl) (i.e. parallel to the basal pinacoid) perfect; m(110) less so. Fracture conchoidal, Brittle. Hardness = 2. Specific gravity = 1.89-1.90. Easily fusible. Astringent taste. Luster vitreous. Color, various shades of green, passing into white; becoming yellowish on exposure. Streak uncolored. Subtransparent to translucent. Taste sweetish, astringent, and metallic. Optically positive. Axial plane parallel to (010). Angle between Z (the slow ray) to c axis = -61º. Refractive indices: alpha (fast direction) = 1.471. beta = 1.478. gamma (slow direction) = 1.486. 2V (the acute bisectrix) = 86º.
Composition - Hydrous ferrous sulphate, FeS04.7H20 = Sulphur trioxide 28.8, iron protoxide 25.9, water 45.3 = 100. Manganese and magnesium sometimes replace part of the iron.
Observations on Occurrence etc. - This salt usually results from the decomposition of pyrite or marcasite, which readily afford it, if occasionally moistened while exposed to the air. It is found in small amounts in many localities. Some of the more important are: Rammelsberg near Goslar, Harz Mts.; Bodenmais, Bavaria; in stalactites from the pyrite mine at Sain Bel, near Lyon, Rhone, France. From Falun, Kopparberg, Sweden. From Cornwall. In the United States found as small fibrous crystals at Leona Heights, Alameda Co., California and is present at Copperas Mount, Ohio and elsewhere . Luckite (1.9 per cent MnO) is from the Lucky Boy mine, Butterfield Canon, Salt Lake Co.,Utah.

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Celia Fiennes Visits the Brownsea Copperas Workings in 1682

Archaeologists of the Poole Harbour Historic Trust are excavating old copperas workings on Brownsea Island, Poole Harbour, Dorset, UK, 21st May 2008

"We went to a little Isle called Brownsea 3 or 4 leagues off [Poole] where there is much Copperice made, the stones being found about ye Isle in ye shore in great quantetyes,

- there is only one house there which is the Governours, besides little fishermens houses, they being all taken up about ye Copperice works; they gather ye stones and place them on ground raised like the beds in gardens, rows one above the other, and are all shelving so that ye raine dissolves ye stones and it draines down into trenches and pipes made to receive and convey it to ye house; yeh is fitted with iron panns foursquare and of a pretty depth at least twelve yards over, they place iron spikes in ye panns full of branches and so as ye liquor boyles to a candy it hangs on those branches: I saw some taken up it look't like a vast bunch of grapes, ye collour of ye Copperace not being much differing, it lookes cleare like sugar-candy, so when ye water is boyled to a candy they take it out and replenish the panns with more liquor; I do not remember they added anything to it only ye stones of Copperice disolved by ye raine into liquour as I mention'd at first; there are great furnaces under, yt keepes all the panns boyling; it was a large room or building with Severall of these large panns; they do add old iron and nailes to ye Copperass Stones. This is a noted place for lobsters and crabs and shrimps, there I eate some very good".

This is from a description of a visit to Brownsea Island by Celia Fiennes in 1682 (extract from Cochrane, 1970). The visitor, Celia Fiennes was born in 1662 at Newton Toney, Salisbury, the daughter of a colonel in Cromwell's army. She is remarkable for the journeys she made, riding side-saddle through every county in England, accompanied by two servants.

(For more of Celia Fienne's travels see:
(part of) A Vision of Britain through Time. )

Norden's map of 1595 showing the location of copperas houses at Alum Chine and Boscombe, Bournemouth, Dorset

Another major area in the past for production of copperas was Boscombe and Alum Chine. The removal of pyrite and production of copperas started rather earlier there than on Brownsea Island. All these localities were exploited under a licence from Queen Elizabeth the First to Lord Mountbank of Canford Manor. For more information on the geology this region please go to the Bournemouth geology webpage.

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5 - LOCATION - SOUTH SHORE continued:

Pyrite (Iron Pyrites) in the Parkstone Clay

For larger-scale economic use, pyrite used to be collected so that copperas could be produced from it by weathering. On Brownsea Island pyrite was collected and quarried or mined for copperas production. The exploitation started in the days of Queen Elizabeth the First. Large lumps of the source mineral pyrite can be still be seen on the beach. The Poole Harbour Heritage Project is investigating the history including the brick remains of an old copperas plant which is present near to the exposures of the pyrite.

A mass of pyrite of the type probably used for copperas manufacture in historic times, South Shore of Brownsea Island, Poole Harbour, Dorset, UK, photo 2007

A line of lumps of pyrite-cemented sandstone on the south shore of Brownsea Island, Poole Harbour, Dorset,UK

An old geological map of the Studland and Sandbanks area, Dorset, showing the location offshore of pyrite pipes in the Poole Formation, Eocene

Pyrite is well-developed in various parts of the Poole Formation. This iron sulphide is easily oxidised above the water table, though and thus is not very obvious in cliffs of the Hampshire and Dorset area. It is best preserved at and below sea level, and can be found in places in beach exposures. Large lumps are visible in the Parkstone Clay on the southern shore of Brownsea Island.

It is possible, although not proven, that is at about the same horizon as the notable "petrified forest" of pyrite pipes in Poole Bay, that is known to local divers. It is approximately on the same line of strike.

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5 - LOCATION - SOUTH SHORE continued:

Iron Cementation from Oxidation of Pyrite

A chalybeate spring on south shore of Brownsea Island, Poole Harbour, stains the pebbles brown, May 2008

Oxidation of pyrite in the Parkstone Clay Formation, Eocene, of Brownsea Island, Poole Harbour, Dorset, produces chalybeate springs, the iron from which locally cements the beach

Iron-cemented beachrock associated with ferruginous waters from oxidising iron pyrites and the formation of jarosite, south coast of Brownsea Island, Poole Harbour, Dorset,UK

The oxidation of pyrite FeS 2 , produces, in general terms, suphuric acid from the sulphide and ferric hydroxide from the iron. The iron hydroxide fixes parts of the beach with a rusty cement. Thus, a special type of ferruginous beachrock is formed in places on the south shore of the Island.

5 - LOCATION - SOUTH SHORE continued:

Coast Erosion Rate indicated by Iron Cementation

A ferruginous beachrock is produced by iron-rich springs from oxidation of pyrite in the Parkstone Clay, Brownsea Island, Poole Harbour, Dorset, UK, May 2008

Cliff erosion behind the iron-cemented beachrock of South Shore, Brownsea Island, Poole Harbour, Dorset, UK, in 2010

The iron-cemented beachrock was examined in May 2008 and again on the 20th June 2010, during a visit by a party from the Open University Geological Society. Compare the photographs above; they show the same location. The fallen tree has been washed away and the cliff has now retreated up to about two metres back from the cemented beach. The cementation which was up to the foot of the cliff in 2008 has probably formed over some period of time when the beach was relatively static in position. Ferruginous water has probably seeped down through the beach sand and cliff debris and slowly cemented quite an appreciable stretch. Now the cliff is retreating faster than the cementation process is occurring. The cemented beach can be used as a marker to show rate of retreat. Further study is needed.

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Iron Cementation at Middlebere Heath

Multiple-type, iron-oxide-cemented pipes, Parkstone Sand Member of the Poole Formation, Middlebere Heath, near Wareham, Dorset, 10th August 2011

Unusual cementation of Eocene sand by limonite or goethite is an interesting feature of a flat-topped hill on Middlebere Heath, to the southwest of Brownsea Island, and near Norden and Corfe Castle. The origin of this may be related to the Browsea Island pyrite occurrence. See the Middlebere Pipes section of the Studland-Tertiary webpage. The Parkstone Clay Member which contains the pyrite at Brownsea Island is present on the southern part of this heath. It thins out northward and may almost completely wedge-out. However it is just north of the feather edge, that there is a hill top occurrence of strange ferruginous pipes and also sheets of limonite. These deposits have been found by Mark Ordish. It is quite likely that they are products of oxidised pyrite, perhaps from a thin relic of the Parkstone Clay. It is quite likely that the pyrite bed, used for copperas on the island, is present on the mainland to the south and southwest. It is not known whether there were any historic workings there.

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The Pottery Works, 19th Century

The Pottery of soutwest Brownsea Island, Dorset, in about 1854, oblique, colour aerial view

A map of the southwestern part of Brownsea Island, Poole Harbour, Dorset, as it was in 1857 when the pottery industry was operating here

Ian West with remains of pipes near the site of the Branksea Pottery, Brownsea Island, Poole Harbour, Dorset,UK

Notice regarding the Brownsea potteries from 1881, Brownsea Island, Poole Harbour, Dorset,UK

The Parkstone Clay (originally know as part of the Bagshot Beds) of the Eocene, Poole Formation Brownsea Island has been worked in the past for pottery. The clay occurs on low ground on the south and north sides of the island, beneath the Branksome Sand. The history of the pottery industry here is of interest. Colonel William Waugh bought Brownsea Island in 1852 for £13,000, a high price at the time (Legg, 1989). His wife was an amateur geologist who noted the presence of clay on the island. A professional geologist, asked to investigate, reported a most valuable bed of the finest clay worth at least £100,000 an acre, but this was an unduly optimistic report. Waught, however, was convinced that fine porcelain would be made and raised money for development. Brownsea Pottery was built at the southwest corner of the island, opposite Furzey Island, and produced pottery, bricks and tiles. There is a good map of this area, made in 1857, in Battrick and Lawson (1978) . A tall chimney above the main set of kilns was a harbour landmark. In the middle of the northern shore was main clayfield where numerous shafts were sunk. There was also a brickworks. A mile-long tramway connected the various workings (Legg, 1989). Waugh had arranged large loans for the enterprise through the London and Eastern Banking Corporation of which we was a director. He also spent large sums of money on other, rather pointless schemes. Unfortunately for Waugh, the bank came to the brink of insolvency and shareholders demanded that Waugh repay the debts. The Brownsea clay had proved unsuitable for fine porcelain and was only of use for terracotta and bricks and Waugh could not make the repayments. He became bankrupt and fled to Spain. In 1870 the island was sold to Augustus Cavendish Bentinck for £30,000. He ran the pottery industry until 1887 with the working force declining from 300 men to only 100 men at the close. (See Legg (1989) for further information and a reproduction of an old etching of the "Branksea Pottery Works".)

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8 - LOCATION - Pottery Pier

Pottery Pier at the northwestern corner of Brownsea Island, Poole Harbour, Dorset, UK, May 2008

An eroding cliff of Branksome Sand over Parkstone Clay at the northwest end of Brownsea Island, Poole Harbour, Dorset, UK, May 2008 .


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The Harbour Floor around Brownsea Island

Aerial view of the southeastern part of Brownsea Island, Poole Harbour, Dorset,UK, showing the harbour floor south of Harry Point

Aerial photograph of the harbour floor south of the southeastern part of Brownsea Island, Poole Harbour, Dorset,UK, with sand lineations and megaripples or subaqueous dunes

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Relationship of the the Wytch Farm oilfield to Brownsea Island and part of Poole Harbour, oblique aerial view towards the south, 6th July 2013

The rig for the Goathorn Extended Reach oil boreholes, seen from Brownsea Island, Poole Harbour, Dorset, UK, 2010

The southern half of Brownsea Island lies above part of the Sherwood Sandstone reservoir (the lower reservoir) of the Wytch Farm Oilfield. The Bridport Sands reservoir approaches the south shore of the island. Across the channel to the south of Brownsea Island is the Goathorn Peninsula. Here the Extended Reach Drilling Borehole of BP has broken records for lateral drilling. Boreholes penetrate the Sherwood Sandstone reservoir from beneath and extend more than 10 km. eastward into Poole Bay. The terminate south of Bournemouth, not far from Bournemouth Pier. The Goathorn drilling rig can be seen from Brownsea Island with the naked eye but it is at a moderate distance and is not conspicuous or obtrusive. The photograph above was taken with a low-power telephoto lens. It is looking southward to the BP drilling rig from the B-P (Baden Powell) Scout Camp area of Brownsea Island. Beyond are the Purbeck Hills of Chalk. From Brownsea Island the rig is just a subject of interest projecting above the forest. Little else of the Wytch Farm oilfield is visible from here, even though Furzey Island, just to the southwest of Brownsea Island has many boreholes and is a major terminal for oil wells. Almost everything is concealed by coniferous trees.

Some Summarised Data on the Wytch Farm Oilfield

(this is merely to give the general picture for educational purposes and is not necessarily up-to-date from a commercial point of view.)

Bridport Reservoir: (Bridport Sands, Upper Lias, a blue-grey marine sandstone, weathering yellow, exposed at West Bay, Bridport, Dorset). Marine sandstone. Depth to crest - 887 m. Oil column 10 to 32m. Permeability in millidarcies - 0 - 300. Production: 2500 bpd. This reservoir was the one original discovered. It is largely produced by beam pumps ("nodding donkeys"). Water injection is used to maintain pressure in the reservoir. Water from Poole Harbour is pumped down.

Sherwood Reservoir: (Sherwood Sandstone, a red desert, fluvial sandstone of the Trias, exposed in cliffs at Sidmouth, Ladram Bay and Budleigh Salterton, Devon). Main reservoir. Depth to crest - 1585 m. 4 to 29m. Permeability in millidarcies - 0.1 - 7000. Triassic fluvial sandstone reservoir, with top reservoir at ca. 1585 m-TVDSS (true vertical depths subsea) with a maximum 110-m column of oil bearing sand above the oil/water contact. The western part of the field lies onshore (below Poole harbour and surrounding area) and the eastern part of the reservoir lies offshore towards Bournemouth Pier. Over half of the Sherwood reserves lies in the offshore area, which necessitated the drilling of ERD (extended reach drilled) wells beginning 1993. Production from Sherwood reservoir accounts for 85% of total WYF production. Normally Occurring Radioactive Material (NORM) is present with the produced fluids and causes complications when retrieving downhole completion and the handling of retrieved ESPs during teardown. The Sherwood reservoir is under almost twice the pressure as the Bridport reservoir. It is not produced by beam pumps ("nodding donkeys") as is the Bridport reservoir.

For more on petroleum geology of Poole Harbour go to: Petroleum Geology, South of England.

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I very much appreciate the help of Alan Holiday in kindly providing oblique aerial photographs of Poole Harbour and Brownsea Island (taken in June 2011). I am particularly grateful to Alan Hawkins and the other, very enthusiastic members of the Poole Harbour Heritage Trust (PHHP) who kindly arranged a specific visit to part of Brownsea Island where copperas workings seem to have taken place. I very much appreciate the helpful discussions of the group and I thank Dr William Sheldrick for copies of his paper and other publications. Geological aspects of the copperas site on Brownsea Island are considered here to some extent; for archaeological information follow the activities of the Poole Harbour Heritage Trust. I much appreciate permission from David Cousins to reproduce his excellent macro-lens photographs of jarosite etc from Brownsea Island. I very much appreciate permission to use aerial photographs and the courteous assistance of the Channel Coastal Observatory ,Channel Coastal Observatory, National Oceanography Centre, Southampton, Southampton University. I particularly thank Travis Mason for help and advice. I am grateful to Dr. Ken Collins for very helpful information on the pyrite pipes of Poole Bay. I must thank Sarah Gardiner of the School of Civil Engineering and the Environment, Southampton University, and whom is researching the sediment budget and geomorpholical history of Brownsea Island, for helpful discussion in the field. I am very grateful to the members of the Open University Geological Society who participated in a meeting on Brownsea Island on the 20th June 2010, and who kindly agreed to be in photographs used on this webpage. I thank Jeremy Cranmer for organising the field trip and John Chaffey for leading half of the party.

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Battrick , J. and Lawson, G. 1978. Brownsea Islander. Poole Historical Trust. 175pp. Hard Cover, ISBN 0 7137 0990 1. By Jack Battrick as told by Gail Lawson. [This has many old photographs, a lithograph of the pottery and its pier (p.17) and a fine detailed map of Branksea Island, dated 1857.]
Introduction: Some years ago now Jack looked after my parents' garden in Sandbanks. In those carefree days I longed for Saturday mornings to arrive when I could chatter to him and persuade him to tell me more about the "Forbidden Island". Brownsea Island, his beloved homeland, lay across the thin strip of twinkling sea which separated Brownsea from the peninsula of Sandbanks.
In Jack's stories, Brownsea held a magic all of its own and its owners and workers attained a fascination which enthralled me.
In later years, as Jack grew older, I began to fear that these tales of the life on Brownsea might be lost for ever. Suzanne Sieger and I had been very close to Jack over the years and were able to persuade him to retell us his stories.
This little book is the result. We very much hope that we have succeeded in letting others feel the charm of Brownsea and the flavour of life as lived on the island. If we have succeeded we shall have enhanced the pleasure of a visit to this peaceful and beautiful sanctuary, and we shall be well pleased.
Jack died this year. We are so sad that he did not live to see the book which he had inspired, for he had so looked forward to seeing it in print.
Gail Lawson, 1978

Bennett , T. 1881. A Sketch of Brownsea Island. 24 pp. Poole, 1881. By Theophilus Bennett, M.A., Vicar.
Betley , J.H. 1982. The production of alum and copperas in Southern England. Textile History, 13, (1) 77-88.
Brannon, P. [date 18??]. The Town and Harbour of Poole, the Isle of Branksea and the Surrounding Scenery. Part 2 of: The Illustrated Historical and Picturesque Guide to Bournemouth and its Neighbourhood. By Philip Brannon, Architect etc.. Poole. Published by R. Sydenham, Longman and Co., London.
Bigham , J.M., Nordstrom, D.K. 2000. Iron and aluminum hydroxysulfates from acid sulfate waters. In: Alpers, C.N., Jambor, J. L., Nordstrom, D.K. (Eds.), Sulfate Minerals - Crystallography, Geochemistry and Environmental Significance. Reviews in Mineralogy & Geochemistry (40), 351-403.
Braye , J. 1890. Swanage (Isle of Purbeck): Its History, Resources as an Invigorating Health Resort, Botany and Geology. 2nd Edition. William Henry Everett and Son, Salisbury Square, Fleet Street, London, 119 pp. (John Braye). Price One Shilling.
Bristow , C.R. and Freshney, E.C. 1987. Geology of Sheet 98NE and parts of SY98NW, SW, SE and SZ08NW and NE (Arne - Wytch Farm , Dorset). Report WA/87/28.

Bristow , C.R., Freshney, E.C. and Penn, I.E. 1991. Geology of the Country around Bournemouth: Memoir for 1:50,000 geological sheet 329 (England and Wales). British Geological Survey, London, Her Majesty's Stationery Office, 116 pp. ISBN 0-110884377-X. Paperback. (Relevant to Tertiary strata of Brownsea Island.)
Bruce , P. 1989. Inshore along the Dorset Coast. Boldre Marine, Lymington. 115p + charts.
Brunsden , D. and Goudie, A. 1981. Classic coastal landforms of Dorset. Geographical Association, Landform Guides, No. 1, 39 pp.
Calkin , J.B. 1968. Ancient Purbeck: an account of the geology of the Isle of Purbeck and its early inhabitants. The Friary Press, Dorchester, 61pp. With 48 illustrations. Paperback booklet. Price 6 shillings. By J. Bernard Calkin, M.A., F.S.A. [With notes and illustrations regarding dinosaur footprints, fossil leaves, Roman mosaics, Purbeck Marble, Kimmeridge oil shale objects etc.]
Canning , A. D. and Maxted, K.R. 1979 (reprinted 1983). Coastal Studies in Purbeck: A Geographical Guide. Printed and Published by the Purbeck Press, Swanage, Dorset. 86 pp., paperback, ISBN 0 906406 07 2.
Chandler , M.E.J. 1962. The Lower Tertiary Floras of Southern England. 2. Flora of the Pipe-clay Series of Dorset (Lower Bagshot). British Museum (Natural History), London.

Chandler, M.E.J. 1963. The Lower Tertiary Floras of Southern England. 3. Flora of the Bournemouth Beds; the Boscombe and the Highcliff Sands. British Museum (Natural History), London.

Chandler, M.E.J. 1964. The Lower Tertiary Floras of Southern England. 4. A Summary and Survey of Findings in the Light of Recent Botanical Observations. British Museum (Natural History), London.

Chandler, M.E.J. 1978. Supplement to the Lower Tertiary Floras of Southern England, Part 5. 47p. Tertiary Research, Special Paper 4.
Cochrane, 1970. Poole Bay and Pubeck 300BC -AD1660. Printed by the Friary Press, Longmans Ltd., Dorchester. 9pp. Paperback. By Mr. C. Cochrane of Bournemouth, also the author of: The Lost Roads of Wessex. [This is a good book with much useful detail on the area. It has a short bibliography and some maps, both old and new.]

[Example extract - p.9 - The Borders of Poole Harbour, introductory part.]

"Nowadays, in the 1970s, it would be hard to find a vacant plot of land from the Haven Hotel at Sandbanks, where the car ferry plies its incessant passage to Shell Bay, to Fleets Corner beyond Poole, or inland to Wimborne and Christchurch. Westward there is a slight gap between Lytchett Matravers and Sandford (for the lately vacated Admiralty cordite factory at Holton has not yet been turned over to building), but from Sandford the new housing estates run through to Wareham and Stoborough.

Only there, and thanks to the Purbeck landlords, can be found recognition of the open heath that still surrounds Corfe Castle and isolates Swanage; and that till lately provided the rather dreary, sometimes foreboding, background to the entirety-ninety-odd miles - of Poole Harbour. Till lately. . . the peninsula of Sandbanks, the North Haven as it was known, must include today some of the most expensive residential property in all England. Sixty years ago the whole spit of land was on offer for (could it be?) a thousand pounds. That is the measure of it.
Across the harbour entrance from Sandbanks, at Shell Bay or South Haven as is its proper name, there remains mile upon mile of untouched heath, a potential klondyke at which many a land speculator must have pursed his lips. The privately-owned toll road, built with the car ferry in the 1920s, runs from the point towards Studland. An unambitious building or two provide teas for summer visitors. A few houseboats nestle out of sight in a harbourside creek. The walker can wander some three miles along the broad sandy coastline to Studland; five miles, finding his way from track to track, to Corfe Castle; or eight to nine or more in a determined ankle-testing foray to Wareham. Away from the beaches he will meet little company other than an occasional farm or forestry worker, or naturalist. For this is a country beloved of botanists and birdwatchers whose rather pompous "keep off" signs are more plentiful than pedestrians."
Dana , E.S. 1932 ed. (early edition 1922, based on Dana edition without Ford 1898), revised by W.E Ford. A Textbook of Mineralogy with an Extended Treatise on Crystallography and Physical Mineralogy. John Wiley and Sons Inc., New York, 851pp. By Professor Edward Salisbury Dana, late Emeritus Professor of Physics at Yale University, and Professor William E. Ford, late Professor of Mineralogy and Curator of the Mineral Collections, Sheffield Scientific School of Yale University. [This is a version of Dana, E.S. an old classic mineralogy textbook, revised by Ford, W.E., and very good for mineralogical reference, although not with as much information as the full Dana Mineralogy]
Dorset's Important Geological Sites Group (DIGS) . 1997. The Geology of Brownsea; Incorporating a Guide to the Geology Trail. 12pp. with a location map. Brochure, 30 pence from the National Trust on Brownsea Island. Prepared by Dorset's Important Geological Sites Group.
Diver , C. 1933. The Physiography of the South Haven Peninsula, Studland Heath, Dorset. Geographical Journal, 81, p. 404 et seq. (Classic work on the growth of the peninsula. The key maps of this have been much reproduced elsewhere, and can be seen in Arkell, 1947, for example.)
Fiennes, C. 1699. In Sydenham, J. 1839. History of Poole. By Celia Fiennes [also available on the internet, and there is an extract in Cochrane, 1970.].
Haigh , M.J. 1975. A biogeographical reconnaissance of the coastal marshlands of Poole Harbour, Dorset.
Harris , S. (Steve Harris). 2007 (reprinted 2007 and 2008). Scout Island!. The Story of the World's First Boy Scout Camp, and More ... Lewarne Publishing, London. 56 pp. A paperback booklet that can be purchased from the National Trust on Brownsea Island, 5 pounds, 99 pence in 2010.
"Introduction: Most people today know the name Baden-Powell. Born 150 years ago, his legacy is the world-wide youth movement for boys and girls of practically all ages, religions, classes and cultures. But to children and adults living in the reign of Queen Victoria, B.-P. (as he came to be affectionately known) was not the founder of a youth movement but a famous soldier. There were cadets and various boys' brigades but no such thing as a Boy Scout movement..." [continues].
Ordnance Survey , 1:25,000 maps, Outdoor Leisure Series, 15, Purbeck and South Dorset. A specially designed map of this popular recreational area. This is the recommended topographic map for geologists using the area. Aerial photographs are also available from the Ordnance Survey.
Legg , R. 19??. Brownsea: Dorset's Fantasy Island. (History of the island, where Tertiary pottery clay was once worked)

Legg, R. 1989. Purbeck Island. 2nd Revised Edition (first published in 1972). Dorset Publishing Company at the Wincanton Press, Wincanton, Somerset. ISBN 0 948699 08 6. 230 pp. (Much useful historic and topographic and some geological information. Short sections on dinosaur footprints, quarries etc).
Mansel-Pleydell , J.C. 1888. Meeting at Poole; account of the geology of the district. Proceedings of the Dorset Natural History and Antiquarian Field Club, 9, xxxv - xxxviii. With notes by Mr. W. Penny.
Moore , P. 2003. For Nature, Not Humans - Recollections of Brownsea Island under the Ownership of Mrs Bonham Christie. Collected and editied by Peter Moore. Poole Historical Trust, 2003, 79 pp. Peter Moore has been a Voluntary Warden on Brownsea Island for 30 years. He interviewed 30 people who had connections with Brownsea Island during the ownership of the reclusive Mrs Bonham Christie. From these interesting - and in some cases unbelievable, anecdotes he has compiled this book. Paperback booklet, price 9 pounds, 99 pence from the National Trust, Brownsea Island in 2010.
National Trust . 19??, Brownsea Geology Trail - Leaflet. Available from the National Trust Office, Brownsea Island.


Ord , W.T. 1910. In: Hovenden, F., Monkton, H.W., Ord, W.T. and Woodward, A.S. Excursion to Swanage, Lulworth Cove and Bournemouth. Report by the Directors. Proceedings of the Geologists' Association, 21, 510-521.

Ord, W.T. (Dr William T. Ord) 1914. Geology. Pp. 303-356 in: Morris, D, 1914. (Editor - Sir Daniel Morris, K.C.M.G, J.P., M.A., D.C.L., D.Sc., F.L.S., F.R.H.S., President of the Bournemouth Natural Science Society). A Natural History of Bournemouth and District; including Archaeology, Topography, Municipal Government, Climate, Education, Fauna, Flora and Geology. By the Members of the Bournemouth Natural Science Society. 400pp. Published by the Natural Science Society. Sold by Horace G. Commin, 100, Old Commercial Road and Bright's Stores Ltd., The Arcade, Bournemouth. [This is an interesting account written when much was still visible in the cliffs and with some good points not discussed much elsewhere.]
Osborne , R. 1999. The Floating Egg: Episodes in the Making of Geology. 272 pp. By Roger Osborne. Pimplico Edition 1999, Pimplico, Random House, Vauxhall Bridge Road, London. First published in Great Britain by Jonathon Cape Ltd. 1998. [This very interesting book does not mention Brownsea Island but provides good information on the manufacture of alum and the alum industry of Yorkshire.]
Papike , J.J., Karner, J.M., Shearer, C.K. 2006. Comparative planetary mineralogy: Implications of martian and terrestrial jarosite. A crystal chemical perspective. Geochimica et Cosmochimica Acta (70), 1309-1321.
Payne , D. 1953. Dorset Harbours. Christopher Johnson, London. 156 pp with photographs and diagrams. By Donald Payne, with a foreword by Vernon C. Boyle. [See the interesting chapter on Poole Harbour, pp 11-33, with discussion of the pirates, Newfoundland shipping business and pipe clay etc.]
Perkins , J.W. 1977. Geology Explained in Dorset. David and Charles, Newton Abbot, 224 pp. ISBN 0-7153-7319-6. A good explanation of Dorset geology with well-labelled diagrams. Out of print but may be obtainable through Amazon.
Poole Harbour Heritage Project . See the article below by Sheldrick.
Reid , C. 1898. Geology of the Country round Bournemouth. Memoir of the Geological Survey. Sheet 329 (England and Wales). By Clement Reid. This was the first edition. See also the later editions: White (1917) and Bristow et al. (1991).

Reid, C. 1916. Ancient rivers of Bournemouth. Proceedings of the Bournemouth Natural Science Society, 7, 73-82.
Sheldrick , W. 2006. Poole and the birth of the chemical industry. Dorset Life - The Dorset Magazine, August 2006. 3pp. The Dorset Magazine Ltd. Reprinted by Poole Heritage Project Ltd., 6 Western Road, Poole, BH13 7BN (www.poolemaritime.org). Article by Dr. William Sheldrick who explains how the exploitation of copperas at Poole was the earliest example in England of continuous chemical processing. Copperas is hydrated ferrous sulphate, also known as green vitreol. It occurs naturally in small quantities as melanterite but is usually manufactured. Dr Sheldrick notes that the first large scale plant to produce copperas in England was in Parkstone Poole, in around 1564. In 1535 the greenish crystals of melanterite were being recovered from Durley cliffs near what was afterwards known as Alum Chine. James Blount, 6th Lord Mountjoy had copperas and alum works at Parkstone, Boscombe, Alum Chine and Brownsea Island. See the original paper for further details. [The article has a map, old prints and a photograph of the remains of a copperas plant on Brownsea Island]
Short , B.C. 1932. History of Poole. By Bernard C. Short.
Strahan , A. 1898. The Geology of the Isle of Purbeck and Weymouth. Memoirs of the Geological Survey. Her Majesty's Stationery Office, London. 278 pages with a map. (Old classic work with some interesting points)
Sydenham, J. 1839. History of Poole. Reprinted by the Poole Historical Trust.
Thomas , J. and Ensom, P. 1989. Bibliography and Index of Dorset Geology. Dorset Natural History and Archaeological Society. 102 pp. Valuable guide to Dorset geological literature including journal articles, newspaper reports and obscure publications. See also the online version.
Torrens , H.S. 1977. Copperice at Brownsea. Geological Curators Group Newsletter, 1 (9), p.449. By Hugh Torrens.
Trimmer , J. and Bristow, H.W. [date not known to me - Victorian; Bristow and Trimmer published Geological Survey maps sheet 16 and 15 in 1855 and 1856]. By Joshua Trimmer assisted by Bristow. This is a report on the economic potential of the clay of Brownsea Island. This is a document of a few pages in the possession of Dr. William Sheldrick. It is an assessment of the Parkstone Clay under Brownsea Island for the purposes of manufacturing alum. It provides analyses of the aluminium oxide content of the clay. On the basis of that and wrongly assuming all the alluminium could be converted into alum it estimates that the clay was of great value. I am very grateful for this personal communication from the chemist, Dr William Sheldrick, who has a copy and who has considered it critically.
Van Raalte , C. 1906. Brownsea Island. Arthur L. Humphreys, London.
Welch , S.A., Christy, A.G., Kirste, D., Beavis, S.A., Beavis, F. 2007. Jarosite Dissolution I - Trace Cation Flux in Acid Sulfate Soils. By Susan A. Welch, Andrew G. Christy, Dirk Kirste, Sara G. Beavis, and Fern Beavis. Chemical Geology, accepted manuscript 2007.
In order to determine trace metal release, dissolution experiments were conducted with a natural jarosite-group sample under a range of conditions relevant to acid sulfate soils. The reaction is incongruent with respect to the Fe3+-dominant octahedral cation layer and other elements that substitute for ferric iron. Transition metals that substitute into the octahedral site are almost entirely retained in the solid phase, although when Fe3+ becomes increasingly soluble, Cr3+ concentration also increases. The solubility behaviour of Rb+ and Sr2+ generally follows that of K+, although the heavier cations are liberated faster in the early stages of the reaction. The REE are also large enough to substitute for K+, but their behaviour is more complex. The REE distribution of the solutions, when normalized to Post-Archean Average Australian Shale PAAS), show enrichments in the MREE in the dissolution experiments, despite the fact that the initial starting material is enriched in the LREE. Mechanisms for LREE and HREE depletion in solution are discussed.
West , I.M. 1980. Geology of the Solent Estuarine System In "The Solent Estuarine System: an assessment of present knowledge", N.E.R.C. Pubications, Series C, No. 22: 6-18. The estuaries of the Solent, Southampton Water and of Portsmouth, Langstone and Chichester Harbours lie at the centre of the Hampshire Basin. They are the latest of a series of shallow-water bodies that have existed here since the relatively deep Chalk sea-floor was uplifted about 65 million years ago. In the Palaeogene Period (Eocene and Oligocene) a wide variety of sediments accumulated in shallow seas, estuaries, lakes and lagoons and these frequently contain abundant plant and animal remains. These deposits now exist beneath and around the modern estuaries. After their deposition there was a long phase of folding, uplift and erosion during the Neogene (Miocene and Pliocene). Relatively recently, during glacial phases of the Pleistocene, the valleys of the local rivers were excavated to well below the present sea-level before being finally flooded during the Flandrian Transgression which thus created the modern estuaries. It is the Eocene, Oligocene, Pleistocene and Holocene (Flandrian) sediments of the region that are discussed in this account. .... continues
White , H.J.O. 1917. Geology of the Country around Bournemouth: Explanation of Sheet 329 [Geological Survey 1 inch to one mile sheet for Bournemouth]. 2nd Edition. Memoirs of the Geological Survey, England and Wales. Published by order of the Lords Commissioners of His Majesty's Treasury. Printed by J. Truscott and Son, Ltd, under the authority of His Majesty's Stationery Office. 79 pp. [This is an old edition of the Geological Survey Memoir - see also - Bristow, C.R., Freshney, E.C. and Penn, I.E. 1991. Geology of the Country around Bournemouth. Memoir for 1:50,000 geological sheet 329 (England and Wales). British Geological Survey, London, 116p. There is also the first edition by Reid (1898). Preface to the Second Edition by A. Strahan, Director: "The first edition of this Memoir, which was written by the late Mr. Clement Reid, was exceptionally brief, a general memoir descriptive of the Hampshire Basin as a whole having been at that time in contemplation. Circumstances have prevented the preparation of the larger work, and opportunity has now been taken ot the exhaustion of the stock of the original pamphlet to produce a memoir on the lines of other New Series Sheet Explanations... continues .. Much of the ground has been re-examined by Mr. White in order to bring the memoir up to date, but the map remains unaltered as the edition published in 1895 and colour-printed (Drift) in 1904."]
Zacke , A. Voigt, S., Joachimski, M.M., Gale, A.S., Ward, D. J. and Tutken, T. 2009. Surface-water freshening and high-latitude river discharge in the Eocene North Sea. Journal of the Geological Society, London, 2009, vol. 166, issue 5, pp. 969-980. By: Anne Zacke, Silke Voigt, Michael M. Joachimski, Andrew S. Gale, David J. Ward and Thomas Tutken.
A shark-tooth apatite delta 18 O [oxygen] record of the early Palaeogene North Sea reflects changes in regional hydrography by showing variable temperatures and salinities. A 2-4 Ma period in the early Eocene was particularly influenced by substantial surface-water freshening, indicated by a 3-4 per thousand reduction of delta 18O values. The magnitude of the delta 18O decrease indicates a depletion in 18O of surface waters by 2-3 per thousand relative to Eocene mean ocean water. This value is lower than that of coeval lakes reconstructed from freshwater gastropod {delta}18O values from the Paris Basin, suggesting that large rivers with high-latitude catchment areas drained into the North Sea. The period of surface-water freshening began close to the Palaeocene - Eocene thermal maximum, when relative sea-level fall, tectonic uplift and basaltic volcanism caused a temporary isolation of the North Sea. North Atlantic and North Sea surface waters became reconnected during a series of early Eocene transgressions.

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Copyright © 2016 Ian West, Catherine West, Tonya Loades and Joanna Bentley. All rights reserved. This is a purely academic website and images and text may not be copied for publication or for use on other webpages or for any commercial activity. A reasonable number of images and some text may be used for non-commercial academic purposes, including field trip handouts, lectures, student projects, dissertations etc, providing source is acknowledged.

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Dr Ian West, author of these webpages

Webpage - written and produced by:

Ian West, M.Sc. Ph.D. F.G.S.


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.