Where perhaps some beauty lies,
The cynosure of neighbouring eyes."
With a little rearrangement of the lines, the sequence we have indicated above would be well illustrated. The mountains must come first; then the clouds, ready to bring forth their rain; then the brooks and rivers, then "russet lawns and fallows grey,"—with their "nibbling flocks." Then come the human elements in the scene,—the "towers and battlements," containing armed warriors, well fed, no doubt, and ready to do their master's bidding; lastly, the lady who adorns the home of her lord, and, let us hope, makes it worth fighting for.
For commercial purposes, large navigable rivers are of great use. And in spite of the modern railway, rivers still exert an influence in determining the routes followed by trade. London, Liverpool, Glasgow, and other busy centres of life owe their importance to the rivers which flow through them, especially since they are tidal rivers. Heavily laden barges may be seen from London Bridge going up and down with the tide every day.
Since the direction as well as the existence of large rivers is regulated by mountains, it is clear that mountains have a very direct influence on the trade of the world.
Mountains supply many of our wants. Besides water and soil, how many useful things come from the hills! Their slopes, watered by the clouds, frequently support an abundant growth of pine forest; and thus we get wood for the shipwright and joiner. Again, mountains are composed of harder rocks than we find in the plains, and that is one reason why they stand out high above the rest of the world. Their substance has been hardened to withstand for a longer time the destruction to which all rocks are subjected. They have been greatly compressed and generally more or less hardened by subterranean heat. We bake clay and make it into hard bricks; so Nature has baked and otherwise hardened the once soft strata of which mountains are chiefly composed, converting them into slates, schist, gneiss, and other kinds of rock called "metamorphic" by geologists, because they have been altered or metamorphosed from their original condition (see chapter viii., page [277]). Again, granite, basalt, and other rocks known as "igneous," which once existed in a molten condition, have forced their way up from subterranean regions into the rocks forming mountain-chains; and a good deal of the hardening just alluded to is due to the presence of these fiery intruders, which have baked and hardened the rocks around them to a considerable extent, altering at the same time their mineral composition. The same causes which led to the injection of granite, basalt, and other igneous rocks in mountain-ranges brought other consequences in their train. Whatever the causes, they were closely connected with volcanic eruptions, so that highly heated water and steam found their way through cracks and other fissures in the rocks; and in the course of time the chemical actions thus set up led to the deposition of valuable metallic ores within these fissures. In this way mineral veins were formed; and volcanic action seems to be largely responsible for the production of minerals. Thus we find around Vesuvius, and in fact in all volcanic regions, large and varied supplies of minerals. Now, the geologist discovers that many mountain-chains—such, for example, as the Grampians, Alps, and Carpathians—have in past geological periods been the seats of volcanic action on a grand scale; and so we need not be surprised to learn that mountainous countries yield large supplies of valuable gems and metallic ores (see chapter viii., page [277]). Even in the days of Solomon, the active and business-like Phœnicians were carrying on trade with Great Britain; and the tin came from Cornwall. Besides tin, gold, silver, lead, copper, zinc, and other metals come from our hills. Now, however, we get our copper mostly from the Andes, and our gold from Australia or South Africa, because it can be got more cheaply from these countries, to which many of our Cornish miners have emigrated.
Precious stones also come chiefly from the hills, for the same reason; for they were formed at the same time and by the same causes. Cairngorms, agates, chalcedony, jasper, onyx, topaz, diamonds, and many other gems are silent but certain witnesses to the action of subterranean heat, acting long ago on the rocks which we now see standing up high above the general surface of the ground, though once they were buried deep down below the surface. Diamonds as well as gold are often got from the beds of streams, but this is easily accounted for; the streams have washed them out and brought them down from the hills.
The following words from the Book of Job (xxviii. 5) might well be applied to the hills.
"As for the earth, out of it cometh bread:
And underneath it is turned up as it were by fire.