The traditionally named Wenlock Limestone was deposited in the upper Homerian Stage of the upper Wenlock Series (Cocks et al. 1992; Zalasiewicz et al. 2009). The Wenlock Limestone was formalized as the Much Wenlock Limestone Formation by Bassett et al. (1975) (Text-fig. 2) and was divided into three units by Butler (1939). Butler's units were updated according to modern stratigraphic practice by Dorning (1983) to: the Lower Quarried Limestone Member, Nodular Member and Upper Quarried Limestone Member (Text-fig. 3). The MWLF lies largely in the Colonograptus ludensis Graptolite Zone (the last zone of the Wenlock Series) in the Wenlock Edge and Ludlow area of Shropshire, and the inliers of May Hill, Usk, and Woolhope, but shows diachroneity of facies because the MWLF in its easternmost outcrops in the Dudley area of West.
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