Western Longmyndian

geological region, United Kingdom

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July 15, 2026

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The Western Longmyndian is a major division of Late Precambrian rocks in Shropshire, England, named after exposures in the Longmynd Plateau. These rocks, formed between 4.6 billion and 542 million years ago, consist of steeply angled mudstones, sandstones, conglomerates, and volcanic rocks. The Western Longmyndian is primarily composed of the Wentnor Series, which includes purple sandstones and conglomerates, with thicknesses reaching approximately 4,800 meters. This geological region is distinct from the Wenlock Series, which represents rocks deposited during the Wenlock Epoch (433.4 to 427.4 million years ago) and is known for its fossiliferous limestones and siltstones.12

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Longmyndian
…major subdivisions are recognized: the Western Longmyndian and the underlying Eastern Longmyndian. The Western Longmyndian consists of the Wentnor Series, purple sandstones, conglomerates, and some greenish siltstones and shales; thicknesses of about 4,800 metres (15,700 feet) of Wentnor rocks have been measured. The Eastern Longmyndian is subdivided into the overlying…
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…major subdivisions are recognized: the Western Longmyndian and the underlying Eastern Longmyndian. The Western Longmyndian consists of the Wentnor Series, purple sandstones, conglomerates, and some greenish siltstones and shales; thicknesses of about 4,800 metres (15,700 feet) of Wentnor rocks have been measured. The Eastern Longmyndian is subdivided into the overlying…
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