All winter bands of Rocky Mountain trappers under Fitzpatrick and Bridger and Sublette had been sweeping, two hundred strong, like foraging bandits, from the head waters of the Missouri, where was one mountain pass to the head waters of the Platte, where was a second pass much used by the mountaineers. Summer came with the heat that wakens all the mountain silences to a roar of rampant life. Summer came with the fresh-loosened rocks clattering down the mountain slopes in a landslide, and the avalanches booming over the precipices in a Niagara of snow, and the swollen torrents shouting to each other in a thousand voices till the valleys vibrated to that grandest of all music--the voice of many waters. Summer came with the heat that drives the game up to the cool heights of the wind-swept peaks; and the hunters of the game began retracing their way from valley to valley, gathering the furs cached during the winter hunt. Then the cavalcade set out for the _rendezvous_: grizzled men in tattered buckskins, with long hair and unkempt beards and bronzed skin, men who rode as if they were part of the saddle, easy and careless but always with eyes alert and one hand near the thing in their holsters; long lines of pack-horses laden with furs climbing the mountains in a zigzag trail like a spiral stair, crawling along the face of cliffs barely wide enough to give a horse footing, skirting the sky-line between lofty peaks in order to avoid the detour round the broadened bases, frequently swimming raging torrents whose force carried them half a mile off their trail; always following the long slopes, for the long slopes were most easily climbed; seldom following a water-course, for mountain torrents take short cuts over precipices; packers scattering to right and left at the fording-places, to be rounded back by the collie-dog and the shouting drivers, and the old bell-mare darting after the bolters with her ears laid flat. Not a sign by the way escaped the mountaineer's eye. Here the tumbling torrent is clear and sparkling and cold as champagne. He knows that stream comes from snow. A glacial stream would be milky blue or milky green from glacial silts; and while game seeks the cool heights in summer, the animals prefer the snow-line and avoid the chill of the iced masses in a glacier. There will be game coming down from the source of that stream when he passes back this way in the fall. Ah! what is that little indurated line running up the side of the cliff--just a displacement of the rock chips here, a hardening of the earth that winds in and out among the devil's-club and painter's-brush and mountain laurel and rock crop and heather? "Something has been going up and down here to a drinking-place," says the mountaineer.