described. The absolute identity of its aspect, composition, and mode of weathering, might perhaps be sufficient to prove the identity of its nature, but this is put out of all doubt by finding that it is here followed by the same set of beds which succeed to it in that place where the sandstone precedes it, and of which the continuity can be traced between the two points. The drawings (Pl. 2. fig. 1.) which accompany this paper, will explain better than words this very essential circumstance in the geological history of Sky.
There is here an opportunity of tracing by a very perfect natural section the change which it undergoes between the very regular beds which lie near it on the one hand and the irregular surface of syenite with which it is in contact on the other. At this surface it bears no marks of stratification, but is an irregular and almost shapeless mass, while near the former beds, which also consist of limestone, it becomes first vertical and gradually more regular, till at the end its general bearing, although much deformed by counter fissures, partakes most decidedly of the general inclination of the stratified rock, which is here about 25°. In geographical distribution it may be here traced in two divisions, separated from each other by syenite and intersected by trap veins, both of these divisions extending towards Broadford and uniting into one scattered and irregular mass about three or four miles short of that place. The uniformity of its character, as well as its continuity throughout this tract, is such as to leave no doubt that the marble of Broadford already mentioned, and which I shall hereafter more fully describe when I speak of individual minerals, is a continuation of this portion of the limestone beds. When it has once quitted the sandstone that rock is no longer seen, but the whole remaining portions of the limestone, occupying a great space from the hills which skirt the eastern side of Strath to the foot of the syenite mountains on the opposite side, is
