But, besides that no force which can ever be ascribed to a torrent could have removed at once bodies of strata 300 or 400 feet, nay even 800 or 1000 in thickness, which must have been the case if this were the true explanation of the fact, there is a circumstance which may perhaps enable us to explain these phenomena without the assistance of any extraordinary cause. The secondary strata in which the whinstone hills are found in this part of Scotland, are not horizontal, but rise or _head_ towards the west, dipping towards the east. The side, therefore, of the whinstone hills which is precipitous, is the same with that towards which the strata rise. Now, from the manner in which these hills are supposed to have been elevated, the strata are likely to have been most broken and shattered towards that side, while, on the opposite, they had the support of the whinstone rock. They would become a prey, therefore, more easily to the common causes of erosion and waste on the upper side than on the lower. The streams that flowed from the higher grounds would wear them on the former most readily; and the action of these streams would be resisted by the superior hardness of the whinstone, just as the great torrent of the _debacle_ is supposed to have been. It should also be observed, that this fact of the uniform direction of the abrupt faces of mountains, is often too hastily generalized. In primitive countries, it is no farther observed than by the steep faces of the mountains being most frequently turned toward the central chain. In Scotland, as soon as you leave the flat country, and enter the Highlands, the scarps of the hills face indiscriminately all the points of the compass, and are directed as often to the east as to the west.