| Computer Code: |
UGRC |
Preferred Map Code: |
UGrC |
| Status Code: |
Index Level |
| Age range: |
Valanginian Age (KV)
— Valanginian Age (KV) |
| Lithological Description: |
The unit comprises soft grey mudstones and silty mudstones the top of which commonly weathers to a red colour. In some areas the Cuckfield Stone Bed occurs at the base. |
| Definition of Lower Boundary: |
The lower boundary is an up-section change from fine-grained, silty, cross-bedded, buff sandstone with local thin mudstones and limestones (Cuckfield Stone Member) up into mudstones (Upper Grinstead Clay unit) that commonly have a marked basal pebble bed (Cuckfield Pebble Bed). |
| Definition of Upper Boundary: |
The upper boundary is placed at the up-section conformable change from mudstones (Upper Grinstead Clay unit) up into the silt and sand rhythms of the upper unit of the Tunbridge Wells Sand Formation. The top of the Grinstead Clay unit is commonly red stained, which helps to emphasise the contact. |
| Thickness: |
Up to 12.2m proved. |
| Geographical Limits: |
The Upper Grinstead Clay unit is recognised at a number of localities on the eastern part of the Horsham district (sheet 302) from the Scaynes Hill area, east to the Cuckfield-Handcross-Balcombe area and then northeast to East Grinstead. On the Tunbridge Wells sheet (287), it is present between East Grinstead and Royal Tunbridge Wells, with a further small outcrop near Danehill. On the Sevenoaks sheet (287) the unit is restricted to a small area near Finch Green and it is again present along the northeastern margin of the Brighton and Worthing Sheet (318/333), where it is found in a small area north of the Lunce's Common Fault, north of Burgess Hill. See also the Lexicon entry for Grinstead Clay Member (GRC). |
| Parent Unit: |
Grinstead Clay Member (GRC)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
Whitemans Green. Gallois & Worssam, 1993 |
| Reference Section |
Pit at Hillhouse Farm. Gallois and Worssam, 1993. |
| Reference Section |
Hammond's Farm. Gallois & Worssam, 1993. |
| Reference Section |
Cuckfield Borehole TQ22NE2 between 166.04 and 178.27m depth. Gallois & Worssam, 1993 |
| Reference Section |
Pit at Great Bently. Gallois & Worssam, 1993 |
| Reference Section |
Haywards Heat Road, Ardingley. Gallois and Worssam, 1993. |
| Reference Section |
Old quarries 275m south of the west end of Lyewood Railway Tunnel. Gallois & Worssam, 1993. |
| Reference Section |
Freshfield Lane Brickworks. Gallois and Worssam, 1993. |
| Reference(s): |
| Young, B and Lake, R D. 1988. Geology of the country around Brighton and Worthing. Memoir of the British Geological Survey, Sheet 318 and 333 (England and Wales). |
| Bristow, C R, and Bazley, R A. 1972. Geology of the country around Royal Tunbridge Wells. Memoir of the Geological Survey of Great Britain, sheet 303 (England and Wales). |
| Dines, H G, Buchan, S and Bristow, C R. 1969. Geology of the country around Sevenoaks and Tonbridge. Memoir of the Geological Survey of Great Britain, Sheet 287 (England and Wales), 183pp. |
| Gallois, R W and Worssam, B C. 1993. Geology of the country around Horsham. Memoir of the British Geological Survey, Sheet 302 (England and Wales). 130pp. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E287
E302
E303
E318
E333
|
