The BGS Lexicon of Named Rock Units — Result Details

Totternhoe Stone Member

Computer Code: TTST Preferred Map Code: TtSt
Status Code: Full
Age range: Cenomanian Age (KE) — Cenomanian Age (KE)
Lithological Description: A distinctly harder unit in the Grey Chalk Subgroup ("Lower Chalk"). Typically brownish-grey, fine-grained calcarenite. Has been described as "sandy" because of coarse fossil fragments - not because of quartz sand grains. Thin to thickly bedded. Phosphatic in part with dark brown pellets a few mm across, up to nodules several cm across. Fossiliferous. Locally used as a building stone.
Definition of Lower Boundary: The base is commonly an indistinct conformable boundary with the underlying West Melbury Marly Chalk Formation ("Lower Chalk", "Chalk Marl" unit) but there may be an erosion surface with a concentration of phosphatic pebbles in the base of the Totternhoe Stone above. May be difficult to locate, even in sections.
Definition of Upper Boundary: The top is commonly an indistinct conformable boundary with the overlying strata of the Zig Zag Chalk Formation ("Lower Chalk", "Grey Chalk" unit). Upward reversion to softer, finer-grained more typical chalk or marly chalk. May be difficult to locate, even in sections.
Thickness: 0.3 to 6.0m in the Hitchin district. Typically 1 to 2m thick but expanded sequences in synsedimentary channels may be up to 6m thick.
Geographical Limits: Known from Berkshire, Hertfordshire and Cambridgeshire where the Southern Province and Transitional Province overlap. Thickest development through Bedfordshire, Hertfordshire and Cambridgeshire, thinning again in Suffolk and Norfolk.
Parent Unit: Zig Zag Chalk Formation (ZZCH)
Previous Name(s): Cast Bed (CASB)
Chilton Stone (-4942)
Alternative Name(s): none recorded or not applicable
Stratotypes:
Type Section  (Type locality and type section) Totternoe Stone Quarry west of Dunstable. Now forms the lowest part of the much larger encircling Lime Workings. Regarded as an expanded atypical sequence, almost 5m thick (Aldiss, 1990). 
Reference Section  Blue Lagoon, Arlesey. c 1.0m in typical shelf facies. 
Reference Section  In the Hitchin district the Green Lagoon [TL 1978 3486], near Arlesey is in thin "shelf" facies. The western face of the disused Chalk Quarry near the redeveloped Fairfield Hospital site shows an atypical "channel" development (Hopson, 1992). 
Reference(s):
Hancock, J M (Editor). 1972. Cretace. Ecosse, Angleterre, Pays de Galles. Lexique Stratigraphique International, Vol.1, fascicule 3a XI. 
Penning, W H and Jukes-Browne, A J, 1881. Geology of the neighbourhood of Cambridge. Memoir of the Geological Survey, Old Series Sheets 51SW and part 51NW (England and Wales). 
Hopson, P M, Aldiss, D T and Smith, A. 1996. The geology of the country around Hitchin. Memoir of the British Geological Survey, Sheet 221 (England and Wales). 
Rawson, P F, Curry, D, Dilley, F C, Hancock, J M, Kennedy, W J, Neale, J W, Wood, C J and Worrsam, B C. 1978. A correlation of Cretaceous rocks in the British Isles. Geological Society of London, Special Report No.9. 
Whitaker, W. 1865. On the chalk of Buckinghamshire, and on the Totternhoe Stone. Quarterly Journal of the Geological Society of London, Vol.21, 398-400. 
Jukes-Browne, A J and HILL, W, 1887. On the lower part of the Upper Cretaceous series in west Suffolk and Norfolk. Quarterly Journal of the Geological Society of London, Vol.43, p.544-598. 
Hopson, P M. 2005. A stratigraphical framework for the Upper Cretaceous Chalk of England and Scotland, with statements on the Chalk of Northern Ireland and the UK Offshore Sector. British Geological Survey Research Report RR/05/01 102pp. ISBN 0 852725175 
Hopson, P M. 1992. Geology of the Letchworth, Northwest Hitchin and Holwell district, Hertfordshire. 1:10 000 Sheets TL 13SE and TL 23 SW. British Geological Survey Technical Report, WA/92/42. 
Aldiss, D T. 1990. Geological notes and local details for 1:10,000 Sheet SP92SE (Totternhoe) and part of Sheet SP91NE (Edlesborough): Part of 1:50,000 Sheet 220 (Leighton Buzzard). British Geological Survey, Onshore Geology Series, Technical Report, WA/90/70. 
1:50K maps on which the lithostratigraphical unit is found, and map code used:
E129 E145 E173 E175 E188 E189 E204 E205 E206 E220 E221 E237 E254