On Beds of supposed Rothliegende Age, near Knaresborough

Abstract

By permission of the Director-General of the Geological Survey I am enabled to lay before the Society a brief outline of some observations made during the past summer in the course of my professional duties. In the neighbourhood of Knaresborough occur certain very well-marked and distinctive grits of a red or purplish-red colour; for the most part these rocks are coarse, frequently quite conglomeratic; oftentimes, however, they are mere sandstones, while in some places they pass into sandy shales. In some localities, as near Plumpton, the proportion of red felspar in the grit is very great, while in others white specks of decomposed mineral matter are scattered profusely through the mass. The quartz-pebbles are very often as large as pigeons' eggs, and form well-marked layers, generally at the base of the separate beds of grit. The grit in the neighbourhood of Plumpton, near Knaresborough, forms most picturesque weathered masses. Between Spofforth and Plumpton, on the slope immediately below the magnesian-limestone escarpment, stand numerous detached pillars and masses of rock, some rising 15 feet above the level of the surrounding ground, others but barely protruding, their surfaces presenting all those curiosities of atmospheric action, in the shape of perforations, basin-holes, honeycombing along the planes of bedding, &c., which, although in many cases difficult to explain fully, yet seem still to be in process of forming. The soil of the fields in which these detached and picturesque rocks rise consists, as one would expect, of the decomposed grit, and seems of a