Lower Estuarine Series
{{Short description|Geologic formation in England}}
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.{{Cite web|url=https://webapps.bgs.ac.uk/lexicon/lexicon.cfm?pub=GRF|title=BGS Lexicon of Named Rock Units - Grantham Formation|website=webapps.bgs.ac.uk}}
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