During our afternoon ride from Tasseremout to the Ourika river, our course lay to the SW., along the base of the escarpment which had so much attracted our notice from a distance; and much discussion arose as to the origin of the vast masses of boulders that were spread along the comparatively level shelf along which we rode, and descended, in some places at least, to the margin of the plain. During the ascent from our camp of last night to Tasseremout, we first made acquaintance with these deposits, at a height of about 3,000 feet above the sea, that of the olive grove at Tasseremout being 3,534 feet. On the slope to the right of our track a mass of irregular weather-worn blocks of sandstone lay in disorder, the most prominent characteristic being that they were all of large size (measuring from ten to twenty cubic yards, according to Maw), with little or no intermixture of finer materials. Maw was disposed to consider these as glacial deposits;[5] but, among other difficulties, it was urged that the moraines of glaciers descending from a great mountain chain always include a large proportion of finer materials along with large blocks, and that these include fragments of the various rocks through which the glacier flows, while it was _primâ facie_ improbable that such a mountain chain as that before us should be altogether formed of the sandstone of which, so far as we could see, the blocks before us were exclusively composed. Soon after leaving Tasseremout, we came to the opening of a narrow valley or ravine cutting through the escarpment, and exposing to view great piles of boulders similar to those seen below, but on a larger scale. After this, the escarpment showed an unbroken face for a distance of about ten miles. Seen near at hand the slope, which from a distance seemed nearly vertical, appeared to have an inclination of from 35° to 45°, and rose to an average height of about 1,000 feet above its base. The upper beds, whose exposed edges were everywhere seen, seemed to consist of hard limestone with siliceous concretions; while the lower beds were of less consistent shaly limestone.