The Geology of the Country Around Kingsbridge and Salcombe

W. A. E. Ussher

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Editore: Forgotten Books
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  • EAN: 9780259634331

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This Memoir treats of the area represented by Sheets 355 and 356 of the New Series of one-inch maps. Since the first edition of these maps was published in 1898, Mr. Ussher has established the fact that the Devonian rocks on the south of the Dartmouth slates are represented by the Meadfoot group which overlies them on the north. These slates, therefore, are the oldest member of the Devonian sequence in this area. As this is a point of great stratigraphical importance it has been deemed advisable to indicate upon the maps the approximate boundary of these two groups, and this has accordingly been done on a new edition which will shortly be published. The boundary is represented by a broken line, which may be followed from the coast near Ringmore (Sheet 355) to the north-east corner of the map. It reappears again near the north margin of Sheet 356 where, owing to folding, the relations of the two groups are more complicated than they are in the adjacent map.

A striking feature of the area in question is the contrast between the intensely folded but comparatively unaltered Devonian rocks in the north and the metamorphic rocks on the south. This has given rise to a somewhat extensive controversial literature which is referred to in the following pages and in which many facts of great importance are described.

The age of the schists is left undecided by the author, though more definite views on the subject have been expressed in favour of their antiquity by Professor Bonney and Miss Raisin, and in favour of their being metamorphosed Devonian rocks by Jukes and Holl, A. Somervail and A. R. Hunt. Although Mr. Ussher has not been able to settle the question of the age of the metamorphic rocks by stratigraphical evidence, his detailed mapping of the green schists and his careful description of the line which separates the altered from the unaltered rocks will be found of value to all future workers in the district.
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