The BGS Lexicon of Named Rock Units — Result Details

Castle Sand and Gravel Member

Computer Code: CASSG Preferred Map Code: notEntered
Status Code: Full
Age range: Mid Pleistocene (QPM) — Late Pleistocene (QPL)
Lithological Description: Predominantly cold-phase sand and gravels that underlie the Castle or First Terrace of the River Bain. Dominated by clasts of flint and chalk (though decalcified near ground surface) and a smaller proportion of Upper Jurassic and Lower Cretaceous lithologies plus minor exotics, notably ?Carboniferous sandstone and 'Bunter' pebbles (mostly derived from Anglian tills). Forms well-developed terrace surface typically about 1 m above modern alluvial floodplain; the deposits extend beneath the latter and are incised into the adjacent Thorpe Terrace. Sections show syndepositional ice wedge casts but no epigenetic casts or cryogenic involutions. Locally includes cold-phase organic silts and peats, but channel-filling organic silts at the base (Tattershall Bed) yield a temperate flora and fauna assigned to MIS 5e. Correlates and merges with the following members of the Trent Valley Formation, Kirkstead Sand and Gravel Member (of the Proto-Trent) and broadly correlates with the combined Beeston and Holme Pierrepont Sand and Gravel Member, and Fulbeck and Scarle Sand and Gravel members (of the Proto-Trent). Middle to Upper Pleistocene (MI Stage 5e to 2).
Definition of Lower Boundary: Unconformable, commonly channelled base, resting on Anglian Wragby Till or (locally) gravels of the Thorpe Sand and Gravel Member in the type area, and possibly locally on Upper Jurassic mudstone bedrock, if present, elsewhere.
Definition of Upper Boundary: Ground surface or against alluvium.
Thickness: 0 to c. 8 m.
Geographical Limits: Bain Valley; currently only separated reliably below Kirkby on Bain. Upstream extent uncertain but probably present at least as far upstream as Horncastle. (BGS sheets 103 and 115).
Parent Unit: Bain Valley Formation (BAINV)
Previous Name(s): Tattershall-Kirkby Terrace Deposits [Obsolete Name and Code: Use THSG, CASSG] (-3275)
Castle Member [Obsolete Name and Code: Use CASSG] (-3902)
Southrey Terrace Deposits [Obsolete Name and Code: Use THSG, CASSG, SOYSG] (-110)
"Lower River Terrace Deposits" [Obsolete Name and Code: Use CASSG] (-2053)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  Tattershall Castle Gravel Pit. Brandon and Sumbler in Bowen, 1999, p.15; Bryant, 1983; Holyoak and Preece, 1985. 
Reference(s):
Brandon A and Sumbler, M G. 1991. The Balderton Sand and Gravel: pre-Ipswichian cold stage fluvial deposits near Lincoln, England. Journal of Quaternary Science, Vol.6. 117-138. 
Bryant, I D. 1983. Periglacial river systems: ancient and modern. Unpublished PhD Thesis, University of Reading. 
Holyoak, D T and Preece, R C. 1985. Late Pleistocene interglacial deposits at Tattershall, Lincolnshire. Philosophical Transactions of the Royal Society of London, Vol. B311, 193-236. 
Lister, A M and Brandon, A. 1991. A pre-Ipswichian cold stage mammalian fauna from the Balderton Sand and Gravel, Lincolnshire, England. Journal of Quaternary Science, 6, 139-157. 
Perkins, N K and Rhodes, E J. 1994. Optical dating of fluvial sediments from Tattershall, UK. Quaternary Science Reviews, Vol.13. 517-520. 
Power, G and Wild, J B L. 1982. The sand and gravel resources of the country around south of Horncastle, Lincolnshire. Description of 1:25 000 resource sheet TF26. Mineral Assessment Report, Institute of Geological Sciences, No.108. 
Rackham, D J. 1981. Mid-Devensian mammals in Britain. Unpublished M.Sc. Thesis. University of Birmingham. 
Bowen, D Q. 1999. A revised correlation of Quaternary deposits in the British Isles. Geological Society Special Report, No. 23. 
Girling, M A. 1977. Tattershall and Kirkby-on-Bain. 19-21 in Catt, J A. Yorkshire and Lincolnshire guidebook for excursion C7, Xth INQUA Congress. 
Jackson, I and Issaias, M D. 1982. The sand and gravel resources of the country around Coningsby, Lincolnshire: description of 1:25 000 resource sheet TF25. Mineral Assessment Report, Institute of Geological Sciences, No.128. 
Rackham, D J. 1978. Evidence for changing vertebrate communities in the Middle Devensian. Quaternary Newsletter, No.25. 1-3. 
Girling, M A. 1980. Late Pleistocene insect faunas from two sites. Unpublished PhD Thesis, University of Birmingham. 
Brandon, A and Sumbler M G. Unpublished manuscript. 
Straw, A. 1958. The glacial sequence in Lincolnshire. East Midlands Geographer, Vol.2, 29-40. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E103 E115