Essex geology report
scattered boulders and used them for a specific purpose although that purpose has yet to be established.
On hearing about the find, the Essex RIGS Group contacted the archaeologists and subsequently
produced a report for them on the geological background to the discovery. It is understood that
BAA wish to exhibit the stone in a prominent position in the airport grounds with an information
board detailing the story of the find. This episode shows how geology can be linked to other sciences
for mutual benefit and publicity.
Field Trips
During the year there have been field trips to Walton-on-the-Naze and to Boreham gravel quarry but
the most notable was to Wrabness and Harwich led by Bill George and Graham Ward on 10th
September. The cliff section at Wrabness shows a sequence of some 34 bands of volcanic ash from
the Harwich Stone Band to the top of the Harwich Formation. According to Daley and Balson in
British Tertiary Stratigraphy (1999) (p6S) Wrabness is the most important site in southern England
at which airborne volcanic, or pyroclastic, deposits of Palaeogene age can be found. The offshore
environment in which the Harwich Formation was deposited is thought to have been broadly equivalent
to the shallow shelf Oldhaven Beds that are present in south Essex and north Kent. Phosphatic
nodules and pieces of whale bone, from the Pliocene Red Crag, which outcrops just a little way back
from the top of the cliff, may be seen at the top of Wrabness beach. Recent finds have included teeth
of Isurus hastalis and Carcharocles megalodon. Some members of the party walked westwards as
far as Wrabness sluice to briefly examine a Pleistocene brickearth which is thought to be 200,000
years old (Oxygen Isotope Stage 7) and forms the cliff and foreshore here.
The party then moved on to Harwich where the Harwich Stone Band is well exposed at the base of
the sea wall and upper part of the foreshore just to the south of the low lighthouse. A few odd
patches of silty clay may be seen on the foreshore, also to the south of the low lighthouse. In the last
few years the height of the beach has dropped by at least 50cm, following extensive dredging of the
harbour channel to a depth of at least 15m in places. Well preserved sharks' teeth occur abundantly
in the beach gravel. Blocks of sandstone, areas of sand and patches of small, black, ovoid pebbles
may be seen on the foreshore at times of very low spring tides. Fossils include shark and fish teeth
and vertebrae, pieces of turtle carapace and limb bones, crocodile scutes, mammal teeth, bird bones
and snake vertebrae. A full field trip report is being prepared.
On 8th July Peter Allen and other specialists in Quaternary geology led a Geologists' Association
trip to a number of Middle Pleistocene sites in Thurrock. Over 20 people were taken to a number of
geological SSSIs including Aveley, Greenlands Pit at Purfleet, and Lion Pit Tramway Cutting in
Grays. On 16th December, members of the International Geological Correlation Programme 437
(IGCP 437; Coastal Environmental Change During Sea-Level Highstands) visited Tilbury Marshes
and Greenlands Pit to see the nature of the field evidence in the Thames estuary for former sea-
levels.
Site news
The Naze, Walton. The wet autumn and winter has led to much erosion at The Naze, particularly at
the northern end. The foreshore platform of London Clay was particularly well exposed after the
winter storms. Several associated sets of fossilised bird bones have been collected from the London
Clay this spring.
Essex Naturalist (New Series) 18 (2001) 103