But even mountain races are often a good deal mixed, and in the Pyrenees we find the descendants of the Iberians, who, a very long time ago, were driven from the lowlands of France and Spain. These Iberians are a very interesting race, of short stature, with long heads, and dark hair and eyes. This old type is to be met with in Wales and the Highlands even in the present day. And so we learn--if these conclusions are sound--that even the Celts in their early days were invaders, and drove before them an older population. This race, it seems, lived in Europe a very long time ago, before the discovery of metals, when people made axes, hammers, and spear-heads out of flints or other stones; and so they are said to belong to "the Stone Age." Their remains are found in many of the caves which of late years have been explored. Possibly the ancient people of Switzerland who lived in wooden houses, erected on piles near the shores of lakes (probably for safety), were also of the same stock. It is curious to find how people living in separate valleys among the mountains of Switzerland have, in the course of time, become so much unlike their neighbours that they can hardly understand each other's speech, so effectually have the mountains kept them apart. In some districts almost every valley has its separate dialect. Switzerland is only twice the size of Wales, yet the local names are derived from half a dozen different languages, three or four of which are still spoken by the people. In the Alps, too, the same mixture of Celtic with an older Iberian stock has been detected. A curious reversal of the usual order of things is noticed by the late Dean Stanley in his "Sinai and Palestine." He points out that the Jews took possession of many of the hills of Palestine soon after the invasion under Joshua, but could not drive out the peoples of the plains, because they were better armed, and had chariots of iron in great number. The conquerors in this case kept to the hills; while the Canaanites, Philistines, and other inhabitants of the country retained for a long time their hold of the lower ground. CHAPTER II. THE USES OF MOUNTAINS. The valleys only feed; the mountains feed and guard and strengthen us.--RUSKIN. It is not an exaggeration to say that there are no physical features of the surface of the earth which render such a variety of services as mountains. The operations which they perform involve such far-reaching consequences that it is difficult to say where their effects cease. Indeed, it might almost be maintained that they are the mainspring of the world,--as far as its surface is concerned,--for it would fare ill with mankind if they were removed or in some way destroyed. Things would then very soon come to a standstill. The soil would become exhausted; streams would cease to flow; and the world would become a kind of stagnant pool. The three main services of the hills are these:--