| Computer Code: |
NACL |
Preferred Map Code: |
notEntered |
| Status Code: |
Full |
| Age range: |
Hoxnian Stage (QX)
— Hoxnian Stage (QX) |
| Lithological Description: |
The Nar Clay Formation consists of finely laminated marine clays, silts and silty clays, and peat of the Nar Valley Freshwater Peat Beds. Brickpits have yielded a rich fauna of well preserved bivalves and gastropods, foraminiferida, ostracods and diatoms. The clay has also yielded the bones and teeth of mammals. |
| Definition of Lower Boundary: |
Clays of the Nar Clay Formation overlie freshwater peat of the Nar Valley Freshwater Beds (NVFB) (which are included in the formation), and oversteps onto a variety of older rocks with marked unconformity. At East Winch the base of the clay is marked by a shell bed composed almost entirely of the oyster Ostrea edulis. |
| Definition of Upper Boundary: |
The Nar Clay Formation is present at surface. It is locally overlain unconformably by the Tottenhill Sand and Gravel Formation (Briton's Lane Formation). |
| Thickness: |
Up to 10 m. |
| Geographical Limits: |
The Nar Clay Formation is restricted to the Nar Valley, Norfolk |
| Parent Unit: |
British Coastal Deposits Group (COAS)
|
| Previous Name(s): |
none recorded or not applicable
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Reference Section |
Tottenhill Gravel Pit (Gallois, 1979). |
| Type Section |
BGS Nar Valley Borehole, Setch, registered No. TF61SE25, 5.6 -17.5 m (Gallois, 1976). |
| Reference(s): |
| Whitaker, W, Skertchley, S B J and Jukes-Browne, A J. 1893. The geology of south-western Norfolk and of northern Cambridgeshire. Memoir of the Geological Survey of England and Wales. |
| Ventris, P A. 1986. The Nar Valley. 7-55 in West, R G and Whiteman, C A (editors), The Nar Valley and North Norfolk Field Guide. [Coventry: Quaternary Research Association.] |
| Athersuch, J, Horne, D J, and Whittaker, J E. 1985. G. S. Brady's Pleistocene ostracods from the Brickearth of the Nar Valley, Norfolk. UK Journal of Micropalaeontology, Vol. 4, No. 2, 153-158. |
| Gallois, R W, 1994. The geology of the country around King's Lynn and The Wash. Memoir of the British Geological Survey, Sheet 145 and part of 129 (England and Wales). |
| Gallois, R W. 1978. The Pleistocene history of West Norfolk. Bulletin of the Geological Society of Norfolk, Vol.30, 3-38. |
| Bowen, D Q. 1999. A revised correlation of Quaternary deposits in the British Isles. Geological Society Special Report, No. 23. |
| Gallois, R W. 1976. Nar Valley Borehole. p 11 in IGS Boreholes 1975. Report of the Institute of Geological Sciences No. 76/10. |
| Lord, A R and Robinson, J E. 1978. Marine Ostracoda from the Quaternary Nar Valley Clay, West Norfolk. Bulletin of the Geological Society of Norfolk, 30. |
| Lord, A R, Horne, D J and Robinson, J E. 1988. An introductory guide to the Neogene and Quaternary of East Anglia for ostracod workers. British Micropalaeontological Society Field Guide, Vol. No.5, 10pp. |
| Mitlehner, A G. 1992. Palaeoenvironments of the Hoxnian Nar Valley clay, Norfolk, England; evidence from an integrated study of diatoms and ostracods. Journal of Quaternary Science, Vol. 7, No.4, 335-341. |
| Stevens, L A. 1960. The interglacial of the Nar Valley, Norfolk. Quarterly Journal of the Geological Society of London, Vol. 115, 291-315. |
| Ventris, P A. 1985. Pleistocene environmental history of the Nar Valley, Norfolk. PhD, University of Cambridge. |
| Ventris, P A. 1996. Hoxnian interglacial freshwater and marine deposits in northwest Norfolk, England and their implications for sea-level reconstruction. Quaternary Science Reviews, Vol. 15, No. 5-6,437-450. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E145
|
