71 676 tonnes of brick clay have been produced from small pits in bleached, weathered metamorphic rocks of the early Proterozoic Houghton Inlier and overlying ? Tertiary sediments. 2 other deposits have previously been investigated. In 1983, 51 auger holes (323.5 metres) in the southern part of the Houghton Inlier suggested that zone of intense weathering is widespread beneath remnants of Tertiary land surface. Firing tests on 3 samples found them to be suitable for brickmaking if blended with other clays to reduce high vitrification temperatures. Material suitable for brickmaking is widespread, but new operations may be difficult due to proximity of houses.