The Lower Estuarine Series is an obsolete term for a thin sequence of fine-grained clastic sediments of Jurassic age, which are now called the Grantham Formation. The rocks of this formation form a lower part of the (Bajocian) Inferior Oolite Group, of Middle Jurassic age. In central England, it normally lies above the Northampton sand and below the Lower Lincolnshire Limestone Member.[1]
The group is found in the East Midlands of England and was formed when the London-Brabant Island was drifting through the low northern latitudes, in conditions represented today by the Sahara Desert. The formation is often only around 2 - 5 metres thick.[1]
References
edit- ^ a b "BGS Lexicon of Named Rock Units - Grantham Formation". webapps.bgs.ac.uk.