"Beginning at the hill-tops," says Geikie, "we first meet with the spring or 'well-eye,' from which the river takes its rise. A patch of bright green, mottling the brown heathy slope, shows where the water comes to the surface, a treacherous covering of verdure often concealing a deep pool beneath. From this source the rivulet trickles along the grass and heath, which it soon cuts through, reaching the black, peaty layer below, and running in it for a short way as in a gutter. Excavating its channel in the peat, it comes down to the soil, often a stony earth bleached white by the peat. Deepening and widening the channel as it gathers force with the increasing slope, the water digs into the coating of drift or loose decomposed rock that covers the hillside. In favourable localities a narrow precipitous gully, twenty or thirty feet deep, may thus be scooped out in the course of a few years." If, however, we trace one of the Swiss rivers to its source we shall generally find that it begins in a snow field or _neve_ nestled in a shoulder of some great mountain. Below the _neve_ lies a glacier, on, in, and under which the water runs in a thousand little streams, eventually emerging at the end, in some cases forming a beautiful blue cavern, though in others the end of the glacier is encumbered and concealed by earth and stones. [Illustration: Fig. 24.--Upper Valley of St. Gotthard.] The uppermost Alpine valleys are perhaps generally, though by no means always, a little desolate and severe, as, for instance, that of St. Gotthard (Fig. 24). The sides are clothed with rough pasture, which is flowery indeed, though of course the flowers are not visible at a distance, interspersed with live rock and fallen masses, while along the bottom rushes a white torrent. The snowy peaks are generally more or less hidden by the shoulders of the hills.