|
PERIOD OR EPOCH |
GEOLOGICAL FORMATIONS IN ESSEX |
|
HOLOCENE |
Recent peat and alluvium |
|
PLEISTOCENE |
River terrace deposits |
|
Boulder clay and glacial gravel |
|
|
Kesgrave Sands and Gravels |
|
|
Norwich Crag (Chillesford Sand) |
|
|
PLIOCENE |
Red Crag |
|
MIOCENE |
No evidence in Essex |
|
OLIGOCENE |
|
|
EOCENE |
Bagshot Sand |
|
London Clay |
|
|
Blackheath and Oldhaven Beds |
|
|
PALAEOCENE |
Woolwich and Reading Beds |
|
Thanet Sand |
|
|
CRETACEOUS |
Chalk (Lower, Middle and Upper) |
|
Gault and Upper Greensand (beneath Essex) |
|
|
No evidence beneath Essex |
|
|
JURASSIC |
|
|
TRIASSIC |
|
|
PERMIAN |
|
|
CARBONIFEROUS |
|
|
DEVONIAN |
Shales and mudstones of Silurian and Devonian age occur at depth (beneath Essex) |
|
SILURIAN |
|
|
ORDOVICIAN |
No evidence beneath Essex |
|
CAMBRIAN |
|
|
PRECAMBRIAN |