Old Red Sandstone

Old Red Sandstone, series of red and brown sandstones, conglomerates, and shales deposited in Wales and Scotland and in England near the Welsh and Scottish borders in the Devonian period of geologic time. The Old Red Sandstone, in contrast to the typical formations of the Devonian, is largely a continental formation, laid down in freshwater and on land as a result of the erosion of the highlands of the Silurian period. It is very thick in Scotland and contains a large assemblage of well-preserved fossils, particularly of the Devonian fishes. The Old Red Sandstone was correlated with the marine Devonian by the British geologists Rodney Murchison and Adam Sedgwick. The New Red Sandstone is a thick red sandstone of Permian and Triassic age found in the British Isles.

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Old Red Sandstone [′ōld ′red ′san‚stōn]

(geology)

A Devonian formation in Great Britain and northwestern Europe, of nonmarine, predominantly red sedimentary rocks, consisting principally of sandstone, conglomerates, and shales.

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Old Red Sandstone 

deposits from the Devonian period (British Isles, northwest parts of the USSR, and other places) consisting of micaceous red and gray sandstone and slate. Frequently found in Old Red sandstone are the remains of fish of the generaCoccosteus, Dipterus, and Holoptychius as well as large anthropods of the genus Eurypterus and specific pelecypods. It is believed that Old Red sandstone is continental and, in part, lagoonal deposits. The lagoons at times were joined with the open sea. The disintegration of the Caledonian mountain system, which had arisen shortly before, aided the accumulation of thick beds of Old Red sandstone.