Petrological Studies in the Harlech Grit Series of Merionethshire. II: The Petrography and Petrology of some of the Grits

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Abstract
The grits which occur intercalated among the Harlech Grit Series have very similar lithological characters throughout. In the field the individual grits are very persistent laterally and can be traced over large areas. During the course of work on the man-ganiferous members of this Series one such grit horizon, which has been termed the “Bluestone Grit”, and which occurs about 5–6 ft.