| Computer Code: |
LGS |
Preferred Map Code: |
LGS |
| Status Code: |
Full |
| Age range: |
Aptian Age (KP)
— Albian Age (KA) |
| Lithological Description: |
Mainly sands and sandstones (varying from well-sorted fine-grained to poorly sorted medium- to coarse-grained) with silts and clays in some intervals. |
| Definition of Lower Boundary: |
In southern England, erosional unconformity or disconformity at base of Atherfield Clay Formation: in most of area overlies Wealden Clay Formation, elsewhere Lower Greensand Group oversteps onto Jurassic rocks. |
| Definition of Upper Boundary: |
Base of Gault; specifically in the Wealden area, base of a short interval of condensed facies beds at the base of the silty clays of the Gault above the sands of the Folkestone Formation. |
| Thickness: |
c.250m in south-western Weald |
| Geographical Limits: |
As described, circum-Weald. Also developed in the Isle of Wight, and less well in Wiltshire to Bedfordshire, Norfolk, Dorset, Lincolnshire and Yorkshire. |
| Parent Unit: |
Not Applicable (-)
|
| Previous Name(s): |
Lower Greensand [Obsolete Name and Code: Use WBS, LGS, WHS]
(-1024)
|
| Alternative Name(s): |
none recorded or not applicable
|
| Stratotypes: |
| Type Area |
Wealden area: see type sections for component parts: Atherfield Clay Formation, Hythe Formation, Sandgate Formation and Folkestone Formation. |
| Reference(s): |
| Rawson, P F. 1992. Cretaceous, 355-388 in Duff, P McL D and Smith, A J (editors), Geology of England and Wales. (London: Geological Society.) |
| Casey, R, 1961. The stratigraphical palaeontology of the Lower Greensand. Palaeontology, Vol.3, 487-621. |
| Waters, C N, Smith, K, Hopson, P M, Wilson, D, Bridge, D M, Carney, J N, Cooper, A H, Crofts, R G, Ellison, R A, Mathers, S J, Moorlock, B S P, Scrivener, R C, McMillan, A A, Ambrose, K, Barclay, W J, and Barron, A J M. 2007. Stratigraphical Chart of the United Kingdom: Southern Britain. British Geological Survey, 1 poster. |
| 1:50K maps on which the lithostratigraphical unit is found, and map code used: |
|
E317
E332
E318
E333
E319
E334
E331
E328
E269
E254
E313
E266
E282
E298
E237
E173
E175
E187
E188
E189
E203
E204
E205
E236
E252
E253
E265
E219
E268
E271
E273
E274
E281
E284
E341
E342
E343
|
