Hull Geological Society

 

Aims
Membership
Publications
Home
Local Geology
Next Meeting
Contact us

Geological Survey of North Cave Wetlands

 

Geological survey 30th November and 20th December 2003.

 

By Barrie Heaton, Colin Clark, Mike Horne, Stephen Whitaker, Stuart Jones, Terry Rocket, Tina and Tony Hibbert.

 

Explorer Sheet 291 1:25000 Map Ref SE 885330

 

The pits are at the eastern edge of the south eastern area of the Vale of York. The surface of the Vale is mainly glacial deposits covered by a thin veneer of alluvium due to flooding down to historic times.

 

The pits are some 7 km north of the River Humber and close to the north west boundary of the village of North Cave. The land to the north, west and south is flat and low lying (only 1 or 2 metres OD to the south). The pits are at 7 metres OD. Immediately to the east the land rises to over 30 metres OD in less than 0.5 km. This slope is part of a narrow north-south ridge of Jurassic rocks, which run parallel to the nearby western scarp slope of the Cretaceous Yorkshire Wolds.

 

Site description - 100 acres of former gravel pits beside Dryham Lane, North Cave. Working stopped about 2000. Now owned by Yorkshire Wildlife Trust and being developed as a Wetlands area for birds. The site was designated a RIGS in December 2003.

 

Brief geology - Brown clay/shales and dark blue/grey clays/shales probably of lowest Jurassic age and perhaps latest Triassic covered by Quaternary gravels.

 

Preliminary report (raw data):

 

Site 0 - SE 88595 32880 - brown shale and brown siltstone with fish scales, in situ at the edge of the lake, >50 cm. Grey limestone in situ 30 cm below the water level, containing 1-2 mm diameter fish scales and deformation features. Auger hole went down about 90 cm through grey clays (brownish, then pale grey, then getting darker) before hitting rock. A second auger hole to the west went through similar sequence, flooded at the bottom and hit rock.

 

Site 1 - SE 88616 22897 - trench in brown and grey shaley clays. The trench base comprised a laminated mudstone from the water level to 65 inches above. The colour of the mudstone varied dark brown at water-level, through pale grey 8 in above, distorted in the trench sides, pale grey interleaved with brown up to 17 in. Above this height up to 40 in the colour was a lighter dark brown, and the top 15 in was light brown with a pale grey band in which light coloured stone pieces (6-8 in wide by 1.5 in thickness) were embedded. These pieces contain fossil bivalves, but there could no confidence that these were in situ.

 

Site 2 - SE 88597 32971 - trench containing back fill over grey and brown clay [Sample] Dark grey mudstone from water level to 30 in height, succeeded by random white thin layered stone interleaved with clay to a height of 40 in. This was capped by red-brown sand coarsening downward and increasingly grey with a thickness of 6 in. This was covered with pebbles mixed with chalk and grey mudstone to a total height of 60 ins above water-level.

 

Site 3 - SE 88588 33037 - trench - 10 ins grey shaley clay above the waterline covered by brown pebbly clay thought to be back fill.

 

Between sites 1 and 3 there are many pieces of 'White Lias' (?) platy white limestone and a shelly limestone. This was not seen in situ but was thought to be local. The fossils seen in the white limestone include Liostrea hissingeri, Protocardia and Pleuromya; indicative of a Rhaetic age.

 

Site 4 - SE 88492 33235 - Northern end of gravel face and adjacent island.

 

Measured section (from top).

 

 Dark grey shales with dark grey siltstone layers containing fossil bivalves, fish scales and ripple marks. Grey cementstones in place below. Fossil wood in the shales but no other macrofossils seen.

 

Notes -

 

Grid references by GPS - accuracy plus or minus 6m.

 

Sites 0 to 3 are in the south-east corner of Lake 5. Site 4 is in the middle of the eastern face of the new lake:- the site sampled is at the northern end of the gravel face, the 'island' is 5 m out into the lake from here and will be covered when the water rises and the 'ramp' is at the south-western end of the gravel section.

 

Water level in the lakes was about 80-90 cm lower than usual. Heights shown on the site plan are relative: add 4.9m to get height OD.

 

Gravels get deeper and thicker to the west; also chalk is replaced by 'sandstone' in the gravels to the west.

 

The Gryphaea fossils collected or seen loose on the site - some were very water worn and others were very fresh - indicating a distance source perhaps derived from tills and a nearer source probably derived from the nearby Lias.

 

Sediment analysis -

 

Sample one [= WET11] (> 63um) - brown silty sand. 80% small quartz grains, half clear and glassy and half frosted and yellow coated. Not as well sorted as some other samples. Some Inoceramus needles, carnelian and chlorite. Derived Chalk foraminifera including Hedbergellids and Heterohelix.

 

Sample three (>63um) - very similar to sample five.

 

Sample five (>63um) - mostly quartz - subangular to rounded: half clear and glassy and half frosted. Quite well sorted. Some carnelian, grey bits. green bits, chalk bits, ?limonitic ?ooliths and Inoceramus needles. Some derived Chalk planktonic foraminifers including Hedbergellids and Heterohelix. Some modern plant material.

 

Sample 8 - Platy or layered weathered shale with calcite inclusions. Devoid of micro-fossils, but contains carbonised vegetation in form of small leaf-like and root-like strands.

 

Conclusions: -

 

The shales and clays may be of Rhaetic or Early Liassic age, but we found no microfossil or macrofossil evidence.

 

The sands and gravels contain derived Lower Jurassic fossils and Upper Cretaceous fossils and microfossils. They may be associated with the Devensian Lake Humber.

 

The source of the jet and loose Gryphaea oysters is probably the gravels. We did not see the shell limestone and plate white limestone in situ - they probably have been brought on to the site from other nearby localities.

 

Acknowledgement - We thank Stephen Martin for allowing access to the site and for providing information about the site.

 

References:

 

Gaunt G D, B N Fletcher and C J Wood, 1992. The geology of the country around Kingston upon Hull and Brigg. British Geological Survey. HMSO London. ix + 172pp.

 

Swift A & D M Martill (eds) 1999. Fossils of the Penarth Group. The palaeontological Association - field guide to fossils no. 9. 312pp.

  

Copyright - Hull Geological Society 2021

Registered Educational Charity No. 229147

Home