The route southward into the Park crosses mountain ridges and over stretches of lava and ashes and other volcanic formations, through woods and past gorges, and reaches the Obsidian Creek, which flows near the Obsidian Cliff. This remarkable structure is a mountain of black glass of volcanic formation, rising six hundred feet, with the road hewn along its edge. It looks as if a series of blasting explosions had blown its face into pieces, smashing the glass into great heaps of _débris_ that have fallen down in front. The formation is columnar, rising from a morass adjoining Beaver Lake, which is a mile long. The divide is thus crossed between the Gardiner and Gibbon Rivers, the latter flowing into the Madison, and here, twenty-five miles from the Mammoth Hot Springs, is the Norris Geyser Basin. In approaching, seen over the low trees, the place looks much like the manufacturing quarter of a city, steam jets rising out of many orifices, and a hissing being heard as of sundry engine exhausts. The basin covers about one hundred and fifty acres, and is depressed below the general level. The whole surface is lime, silica, sulphur and sand, fused together and baked hard by the great heat, cracked into fissures, and, as it is walked over, giving out hollow sounds, showing that beneath are subterranean caves and passages in which boil huge cauldrons. There is a background formed by the bleak-looking mountains of the Quadrate range, having snow upon their tops and sides. The steam blows off with the noise of a hundred exhaust pipes, and little geysers boil everywhere, occasionally spurting up like the bursting of a boiler. In one place on the hillside the escaping steam from the "Steamboat" keeps up a loud and steady roar; in another is the deeper tone of the "Black Growler." As a general thing, the higher vents on the hill give off steam only, while the lower ones are geysers. The trees are coated with the deposits, the surface is hot, and all underneath seems an immense mass of boiling water, impregnated with sulphur, giving off powerful odors, while brimstone and lime-dust encrust everything, and a large amount of valuable steam-power goes to waste.