The Beds Underlying the Magnesian Limestone in Yorkshire.

This paper is the first of a series that the writer hopes to submit on the Permian rocks of the North of England. It deals with a group of rocks which is insignificant in thickness and area of outcrop, yet is the sole representative in the County of the time interval between the Lower Staffordian and the Zechstein. This group has been called by various authors the Yellow Sands,1 Quicksands2 and Basal Sands.3 Their general lithology and mineral content together with their stratigraphical relations to the beds above and below afford important evidence regarding the physiographical and climatic conditions of the interval mentioned above. Little petrographical research has been carried out on these beds. Prof. Gilligan has described the somewhat anomalous outcrop at Conisborough4 and H. P. Lewis5 has called attention to specific points in the Yellow Sands at Nitticarhill. Under the Magnesian Limestone of Durham occurs a series of loosely compacted sands which attain in places a thickness of 150 ft. At no place south of Ferryhill does such a thickness of beds of this age occur, and not until Harthill is reached does their outcrop again become continuous. In Yorkshire the Yellow Sands are found in a number of isolated outcrops and rarely attain a thickness of more than 20 ft. These outcrops occur at Crakehall near Bedale, Scriven, Thorner, Garforth and Kippax, Hampole area, Conisborough and Harthill, while in Nottinghamshire the outcrop becomes continuous and a breccia facies develops. The Geological Survey map of the Harrogate sheet ...