The sand and gravel resources of the country east and south-east of Darlington, Durham. Description of 1:25 000 sheet NZ 30 and 31 / Contributors: J G O Smart, J W C James, A Smith; The sand and gravel resources of sheets NZ 31 and NZ 30 (East and South-East of Darlington, Durham); Scale: 1:25 000Books/Monographs