Common clay and shale

Ridgway, J.M.

Common clay and shale

Ridgway, J.M.. 1982 Common clay and shale. London, UK, HMSO, 171pp. (Mineral Dossier No. 22)

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Abstract/Summary

Clays and shales are argillaceous sedimentary rocks consisting of fine particles of clay and other minerals, the type and abundance of which are determined by source area rocks and climate, as well as depositional environment and diagenesis. Such rocks outcrop over wide areas of the United Kingdom and are represented in practically all geological periods. The structural clay products industry is the largest user of clay and shale in the United Kingdom, but although a very wide variety of horizons and lithological types are utilized, some deposits are unsuitable e.g. many Lower Palaeozoic rocks, or sediments containing unacceptable amounts of impurities. Other deposits may be sterilized by development or there may be environmental pressures militating against extraction. Brickmaking, in one form or another, has been known since at least 8000 B.C. In the United Kingdom today, common clays and shales are used for the production of building and engineering brick, floor and roofing tiles and agricultural field drains. They are also employed in the manufacture of vitrified clay pipe, lightweight aggregate and cement. In 1978 the production of common clay and shale in the United Kingdom was 25.5 million tonnes, of which the heavy clay sector accounted for some 55%. The Oxford Clay remains pre-eminent as the major source horizon for building brick and field drain pipe clays (47% of UK brick pipe and tile production) while Carboniferous shales and the Triassic 'Keuper Marl'* are second and third in importance. The Etruria Marl has retained its traditional markets for top quality engineering bricks and floor and roofing tiles, as well as facing bricks. The trend in the industry recently has been towards rationalization and larger production units, though some 200 works remain spread across Britain from Devon in the south to Grampian in the north. There has been a tendency towards better quality control and often complex blending of raw materials; the production of quality facing brick has greatly outstripped that of common brick, the latter having been largely replaced in internal walling by various dense and lightweight blocks.

Item Type:

Publication - Report

Programmes:

BGS Programmes > Economic Minerals

Funders/Sponsors:

Institute of Geological Sciences

Additional Keywords:

Mineral, Clay, Shale

NORA Subject Terms:

Earth Sciences

Date made live:

12 Aug 2025 09:38 +0 (UTC)