Page:Transactions of the Geological Society, 1st series, vol. 4.djvu/330

 indeed be distinguished (but with more difficulty) if viewed in profile. In the part which I am now describing the lines are narrow and the declination of their surfaces from the horizontal plane is considerable, as the profiles will show. This ground is rocky and irregular, the natural rock being visible in many places, while in the rest of the glen it is but rarely seen; and it may be remarked that wherever the natural rock comes to light these marks or lines are always least discernible, being of much smaller dimensions, and having a much greater conformity in their slopes to the natural slope of the hill. Whatever loose matter occurs here consists of large fragments, which have evidently descended from the hill above. That this is their origin and that they are not transported materials is plain, since they are not rounded and since they exactly resemble the natural rock, which is of a remarkable character, consisting of mica slate traversed by numerous veins of red granite; a rock which is limited to the upper part of the glen and is not found in the neighbouring hills. The natural rock projects in many parts of the line so as to interrupt it; or it is wanting wherever a solid mass of rock occurs in its course. As I am here only describing the appearances, I will not anticipate the arguments by asking whether the line has not been sometimes overwhelmed by the fall of rubbish; in many cases however its obscurity evidently arises from the refractory nature of the materials on which it is traced. Obscure marks of two similar lines are here and there visible on the left hand side in this place, particularly on certain projecting faces where the surface of the hill is, from its outline, evidently covered with a coat of alluvial matter. Independently of these fragments of the two principal lines, many short indistinct traces are to be seen at different levels from those on