Coed-mawr Quarry
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Geology & landscape
Mining / Industrial: Quarry
Description
Description This quarry section has historical and present-day importance through the part it played in the establishment of a modern Wenlock graptolite zonation, which was based by Elles largely on sections in the Builth area. Coed-mawr was cited as one of only two exposures in the Builth district of the C. linnarsoni zone, which here lies above C. rigidus zone strata. This quarry, showing the boundary between these two biozones, is an essential locality in the Builth district, the accepted type area for British Wenlock graptolite zonation. A key biostratigraphic locality. In layman's terms, the interest of this site may be expressed more simply, and such a statement is provided below. This should not be taken as definitive and further information as to details of the interest can be obtained from the Nature Conservancy Council. The quarry at Coed-mawr played a role in the early part of the century when the succession of geological strata in mid Wales was being worked out. Detailed study of a group of fossil animals known as graptolites readily established the sequence of evolutionary changes which these animals had undergone, and on this basis a zonation of the black shales containing these graptolites was established in the Builth area and later applied throughout Britain. Coed-mawr remains one of the key sites in Britain for the study of the Wenlock portion of geological time, some 410 million years ago, and is the accepted reference area for the British Wenlock graptolite zonation.