The Lost Rivers of Idaho.
ONE of the most singular features in the scenery of the Territory of Idaho, is the occurrence of dark, rocky chasms, into which large streams and creeks suddenly discharge themselves, disappear, and are never more seen. These fissures are old lava channels, produced by the outside of the molten mass cooling and forming a tube, which, on the fiery stream becoming exhausted, has been left empty, while the roof of the lava duct having at some point fallen in, presents there the opening into which the river plunges and is lost. At one place on the precipitous banks of the Snake, one of these underground rivers comes gushing into light from a cleft high up in the basaltic wall, where it leaps in the form of a cataract into the torrent below. Where this stream has its origin, or at what point it is swallowed up, is utterly unknown, though it is believed that its sources are a long way up in the north country. Besides becoming the channels of living streams, these lava conduits are frequently found impacted with ice masses, which never entirely melt.