On the Excavation of the Valleys in the Tabular Hills, as shown by the Configuration of Yedmandale, near Scarbro’

Abstract

The Tabular Hills are a range of flat-topped hills, extending from Scarbro’ westwards to near Thirst. They are composed of coralline oolite, or calcareous grit, at the top, overlying Oxford clay, Kelloway’s rock, cornbrash, and the upper sandstone and shales; and their peculiar configuration is very clearly traceable to this structure. The part to which I shall particularly refer is that near Scarbro’. Proceeding from the low flat tract of the vale of Pickering, the surface of the hills rises gradually to the north for some distance, and then the top becomes nearly level, having no undulations, and diversified only by deep-cut ravine-shaped valleys; the configuration and origin of which is the subject to which I wish to call your attention. The nature of these valleys will be best understood from See. 5, Plate III., where a portion of the level top will be seen on both sides, and the ravine-shaped valley cut sharply out, with the sides inclined at an angle of 30°. We have, therefore, in these valleys a case in which it might with considerable propriety be concluded that they had been produced by the action of the streams now running in them, in as much as their form is the same as would be produced by such action, continued for a long period. We have, however, in the case of Yedmandale, an association of circumstances that have, in a remarkable manner, preserved phenomena which clearly prove that they are not due to this agency, but to ...