observed that in that space there are at least three tongues or upward projections of the upper limit of the dyke. Several additional examples of the same structure are to be seen further east towards the last visible outcrop of the dyke. [Illustration: Fig. 242.--Section along the course of the Cleveland Dyke, at the head of Lonsdale, Yorkshire (G. Barrow, in the _Memoirs of the Geol. Surrey_, Geology of Cleveland, p. 61). _a_, Liassic shales, sandstones and ironstones; _b_, the dyke.] Another feature connected with the upward termination of the dyke is well seen in some parts of the ground through which the two foregoing sections are taken. Mr. Barrow informs me that at Ayton a level course has been driven into the hill for mining operations, at a height of 400 feet above sea-level, and the dyke has there been ascertained to be 80 feet broad. Higher on the hill, close to the 750 feet contour--line, its breadth is only 20 feet, so that it narrows upward as much as 60 feet in a vertical height of 350 feet. Its contraction in width during the last twenty feet is still more rapid, and in the last few yards it diminishes to two or three feet, and has a rounded top over which the strata are bent upward. The accompanying section (Fig. 243) across the upper part of the dyke will make these features clear. [Illustration: Fig. 243.--Section across the extreme upper limit of Cleveland Dyke, on the scale of 20 feet to one inch (Mr. G. Barrow). _a_ _a_, Jurassic shales, etc.; _b_, Dyke.] [Illustration: Fig. 244.--Upper limit of Cleveland Dyke in quarry near Cockfield (after Mr. Teall). _a_ _a_, Carboniferous shales; _b_, dyke.] Further to the west an exposure of the upper limit of the dyke has been described and figured by Mr. Teall. In 1882, at one of the Cockfield quarries (Fig. 244), the dyke was "seen to terminate upwards very abruptly in the form of a low and somewhat irregular dome, over which the Coal-measure shales passed without any fracture, and only with a slight upward arching."[189] [Footnote 189: _Quart. Jour. Geol. Soc._ xl. p. 210.]