Grantham Formation
Stratigraphic range: Aalenian PreꞒ Ꞓ O S D C P T J K Pg N ↓
Sproxton Quarry, a Reference Section for the Grantham Formation
Type	Geological formation
Unit of	Inferior Oolite Group
Underlies	Lincolnshire limestone
Overlies	Northampton Sand Formation, Whitby Mudstone Formation
Thickness	2 to 5 m, locally 15 m in channels
Lithology
Primary	Mudstone
Other	Sandstone
Location
Region	England
Country	UK

The Grantham Formation is a geological formation in England, which dates to the Middle Jurassic Aalenian age around 172 million years ago. It is composed of mudstones and sandstone, usually with abundant plant debris. It overlies the preceding Northampton Sand Formation and underlies the following Lincolnshire Limestone.^[1]

It is found from the Humber estuary to the Kettering/Peterborough area.