Everywhere we read the same story, the same circle of changes. The Alpine peak that proudly rears its head to the clouds must surely be brought low, and finally come back to the same ocean from which those clouds arose. It is in this way that the balance between land and water is preserved. In passing through such a great circle of changes, the mountains assume various forms and shapes which are determined by:-- 1. Their different ages and states of decay. 2. The different kinds of rocks of which they are composed, and especially by their "joints," or natural divisions. 3. The different positions into which these rocky layers have been squeezed, pushed, and crumpled by those stupendous forces of upheaval of which we spoke in chapter vi. Let us therefore glance at some of these external forms, and then look at the internal structure of mountains. In so doing we shall find that we have yet a good deal more to learn about mountains and how they were made; and also we shall then be in a better position to realise not only how very much denudation they have suffered, but also how greatly they have been disturbed since their rocks were first made. Every one who knows mountains must have observed how some are smooth and rounded, others sharp and jagged, with peaks and pinnacles standing out clearly against the sky; some square and massive, with steep walls forming precipices; others again spread out widely at their base, but the sloping sides end in a sharp point at the top, giving to the mountain the appearance of a cone. Their diversities of shape are so endless that we cannot attempt to describe them all. First, with regard to the general features of mountains. Looked at broadly, a mountain-range is not a mere line of hills or mountains rising straight up from a plain on each side, such as school-boys often draw in their maps; very far from it. Take the Rocky Mountains, for instance. "It has been truly said of the Rocky Mountains that the word 'range' does not express it at all. It is a whole country populous with mountains. It is as if an ocean of molten granite had been caught by instant petrifaction when its billows were rolling heaven high."[28] [28] "The Crest of the Continent," by Ernest Ingersoll, Chicago, 1885. It has often been observed by mountain climbers that when they get to the top of a high mountain, and take a bird's-eye view of the country, all the mountain-tops seem to reach to about the same height, so that a line joining them would be almost level. For this reason, perhaps, writers so often compare them to the waves of an ocean. This feature is very conspicuous in the case of the Scotch Highlands. Sir A. Geikie has well described what he saw from the top of Ben Nevis:--