On the Western End of the London Basin; on the Westerly Thinning of the Lower Eocene Beds in that Basin; and on the Greywethers of Wiltshire

Abstract

Listen

Translate article

Introduction.—The above three subjects are closely akin to one another. The sections that will be described in the first part of this paper show that the "thinning" treated of ~n the secoucl is greater than has been hitherto thought; and the extent of this latter must much change our notions as to the formation from which have come the greater part of those loose blocks of Greywether-sandstone that, in many places, lie on the surface of Cretaceous and Tertiary beds. The age of the sands noticed in the thud part may also have some bearing on that of the Greywethers. The data on which a great part of this paper is founded have been in my hands for some time ; and the conclusion that I have come to with regard to the age of the Greywethers at the western end of the London Basin has been shortly given in the Geological Survey Memoir on Sheet 13 (p. 48). I have great pleasure in knowing that Prof. Ramsay wholly agrees with my views of the beds in that district, to which this paper chiefly refers. The thinning-out of the London Clay in Marlborough Forest has also been noticed at p. 54 of the above-mentioned memoir. The new points of this paper, which treats of the London Tertiary District alone, are—the proof of the occurrence of the London Clay and the Lower Bagshot Sand further westward than they have been before noticed; the thinmng of the Woolwich and Reading Beds west