The Northampton Sand, sometimes called the Northamptonshire Sand is a geological formation of Jurassic age found in the East Midlands of England. Particularly in the twentieth century, it has been of economic importance as a source of iron ore, but is now worked much less.
The Northampton Sand Formation constitutes the lowest part of the Inferior Oolite Series and lies on the upper Lias clay. It attains a maximum thickness of up to 21 metres (69 ft) to the north and west of Northampton where it lies in a subterranean basin. In the south, it fades out around Towcester. Northward from the edge of the basin in the upper Lias, under Northampton, it lies progressively lower beneath the Jurassic Lincolnshire limestones. A little to the north of Corby Glen (grid reference ) it is at about 50 metres (160 ft) from the surface. It fades out under north Lincolnshire as the strata rise towards the Market Weighton Axis.
There is a description of the twentieth century exploitation of the Northampton Sand for iron-smelting in the Wellingborough article.
- Kent, P. & Gaunt, G.D. British Regional Geology Eastern England to The Wash (1980) ISBN 0-11-884121-1
- Hains, B.A. & Horton, A. British Regional Geology Central England (1969) ISBN 0-11-880088-4
- British Geological Survey 1:50 000 Series. Stamford. Sheet 157 Solid & Drift Edition (1978)