It will be remembered that, when the cutting was made, early in 1846, athwart the shoulder of Arthur's Seat above Samson's Ribs, for the formation of the Queen's Drive, the rock was found hollowed in a trough-form for a space of about eighty yards, and smoothed and striated in the manner of a glacier-bed of the Alps. The striæ were in the direction of the hollow, pointing to east 20° south. The whole was covered over with a brown tenacious clay, containing fragments of rocks of the district, along with some supposed to have come from a distance.