| Computer Code: |
BFLM |
Preferred Map Code: |
BrF |
| Status Code: |
Full |
| Age range: |
Turonian Age (KT)
— Turonian Age (KT) |
| Lithological Description: |
Massive, blocky, soft to hard, white chalk with sporadic thin beds of grey clay-rich chalk (marl) and numerous beds of nodular flint, some very large (about 0.5m or more across), and a semi-tabular flint bed, (the Floorstone of Grimes Graves). |
| Definition of Lower Boundary: |
Conformable. In concept, the lowest extent of the densely-developed large black flints once worked near Brandon, Suffolk; specifically, the lowest extent of the Rough and Smooth Blacks, which comprise several irregularly-developed beds of large black nodular flints that extend between about 3m and 5m below the Grimes Graves Marl (local equivalent of the Bridgwick Marl 1 of the Southern Province and the North Ormsby Marl of the Northern Province - Mortimore and Wood, 1986). Flint development in this part of the sequence can vary over short distances and the Grimes Graves Marl is the most reliable marker in the lower part of this member. The lower boundary might coincide with the base of the P. (S.) plana biozone, or lie a short distance below the top of the T. lata biozone. |
| Definition of Upper Boundary: |
Conformable. For convenience taken at the base of the Chalk Rock, although the concentration of large flints ceases from 2 to 5m lower, at the Topstone or Toppings Flints. |
| Thickness: |
About 10 to 15m between Mundford and Bury St Edmunds. |
| Geographical Limits: |
At outcrop probably occurs at least as far north as about Swaffham (Norfolk) (then passing into equivalent strata of the Northern Chalk Province) and as far south as Bury St Edmunds. Flint becomes less markedly abundant at this level at outcrop at an unknown distance towards the south-west. Seems to occur at least locally in the Saffron Walden district. Absent from most of the Sudbury district, to the south, but possibly present locally. Not present in the Hitchin district. Extent in subcrop to the east and south-east not known but could continue into the equivalent 'Basal Complex' of North Kent. |
| Parent Unit: |
Lewes Nodular Chalk Formation (LECH)
|
| Previous Name(s): |
Brandon Flint Series [Obsolete Name and Code: Use BFLM]
(-4457)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Partial Type Section |
Mine shafts in Poors Plantation, Lingheath, south of Brandon, Suffolk Type section described by Skertchly (1879) from the flint mines (now disused and normally inaccessible) at Lingheath, just south of Brandon, Suffolk. This is complete, except for the topmost few metres up to the Chalk Rock. |
| Reference Section |
Eastern end of disused chalk pit (Taflin's Pit) on south side of Thetford Road, immediately east of Brandon, Suffolk Exposes only lowest part of unit, from the Grimes Graves Marl down to the Rough and Smooth Black flints, into the underlying New Pit Chalk Formation. |
| Reference Section |
Prehistoric flint mine at Grimes Graves, Norfolk. Shaft maintained by English Heritage to allow visitor access. Exposes beds from Topstone to Floorstone, so topmost and lowest parts of unit are not seen here. |
| Reference(s): |
| Green, B. 1990. Grimes Graves. English Hertiage (Second Edition), HMSO. ISBN 1 85074 299 5. |
| 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 |
| Mortimore, R N, and Wood, C J. 1986. The distribution of flint in the English Chalk, with particular reference to the 'Brandon Flint Series' and the high Turonian flint maximum. 7-20 in The Scientific Study of Flint and Chert. Sieveking, G, de G, and Hart, M B (editors). (Cambridge: Cambridge University Press.) |
| Ward, W H, Burland, J B, and Gallois, R W. 1968. Geotechnical assessment of a site at Mundford, Norfolk, for a large proton accelerator. Geotechnique, Vol. 18, 399-431. |
| Skertchly, S B J. 1879. On the manufacture of gun-flints. Memoir of the British Geological Survey. |
| Hewitt, H D. 1935. Further notes on the Chalk of the Thetford district, Norfolk. Proceedings of the Geologists' Association, 46, 18-39. |
| Mortimore, R N, Wood, C J and Gallois, R W, 2001. British Upper Cretaceous Stratigraphy. Geological Conservation Review Series. No. 23. (Peterborough: Joint Nature Conservation Committee.) |
| Bristow, C R. 1990. Geology of the country around Bury St Edmunds. Memoir of the British Geological Survey, Sheet 189 (England and Wales). |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E174
E175
|
