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YOREDALE SERIES

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Originally appearing in Volume V28, Page 924 of the 1911 Encyclopedia Britannica.
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YOREDALE See also:

SERIES , in See also:geology, a See also:local phase of the See also:lower Carboniferous rocks of the N. of See also:England. The name was introduced by J. See also:Phillips on See also:account of the typical development of the phase in Yoredale (See also:Wensleydale), See also:Yorkshire. In the Yorkshire dales the Carboniferous rocks assume an aspect very different from that which obtains in the S. Beds of detrital sediment, sandstones, shales and occasional ironstones and thin coals See also:separate the limestones into well-defined beds. These See also:limestone beds have received various names of local significance (Hardraw Scar, Simonstone, See also:Middle, Underset, See also:Main and many others), and owing to the See also:country being little disturbed by faulting and being much cut up by the streams, they stand out as escarpments on either See also:side of the valleys. The first indication of the intercalation of thick detrital deposits within the massive limestone is seen in Ingleborough and Penyghent; but as the rocks are traced N. the detrital See also:matter increases in quantity and the limestones diminish, till in See also:Northumberland the whole Carboniferous series assumes the Yoredale phase, and consists of alternations of detrital and calcareous beds, no massive limestone being seen. The Yoredale limestones are characterized by the presence of Productus giganteus and the brachiopod See also:fauna usually associated with it. The main limestone of Weardale is full of See also:corals, including Lonsdaleia floriformis, Dibunophyllum sp., Cyclophyllum pachyendothecum, &c., and has a typical Visean fauna; it would therefore correspond, palaeontologically, with the upper See also:part of the Carboniferous Limestone of See also:Derbyshire. On Ingleborough the limestones are not very fossiliferous, but the Main Limestone contains small corals of a zaphrentoid type and an upper Visean fauna. Posidonomya Becheri occurs fairly See also:low down in the series in the Shale above the Hardraw Scar and Gayls limestones, but it is not accompanied by any of the goniatites or other cephalopods and lamellibranchs which characterize the Posidonomya Becheri beds of the Pendleside Series, the faunas of the Yoredale and Pendleside phases being very distinct. The Red See also:Bed Limestone of Leyburn, the upper-most limestone of the series, is very See also:rich in See also:fish remains, which are identical in many cases with those found in the topmost beds of the massive Carboniferous Limestone at See also:Bolt Edge See also:quarry in Derbyshire.

The shales between the limestones are rich in fossils and contain abundant single corals referable to Zaphrentis enniskilleni, Cyclophyllum pachyendothecum and others; these, though high-zonal forms, occur low down in the Yoredale strata, even in the shale above the Hardraw Scar limestone. In the Derbyshire See also:

area and farther N. these corals would indicate the uppermost beds of the limestone series of those districts, and their See also:early See also:appearance in the Yoredale area is probably entirely due to conditions of environment. Attempts have been made to correlate rocks in a number of widely separated areas with the Yoredale strata, but on wholly insufficient grounds. It is clear that the exact relation-See also:ship which the Yoredale series of the type area bears as a whole to the lower Carboniferous rocks of the Midlands, N. and S. See also:Wales, &c., on the one See also:hand, and to the Pendleside series on the other, has yet to be established on a See also:firm palaeontological basis. See Mem. Geol. Survey, " Geology of Mallerstang "; W. See also:Hind, Proc. Yorks. Geol." and Poly. See also:Soc.

(1902), xiv. part iii.; and See also:

Rep. Brit. See also:Ass., " See also:Life Zones Brit. Carb. Rocks " (1901).

End of Article: YOREDALE SERIES

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