Death Gulch is a small and gloomy ravine in the northeast corner of the Yellowstone National Park. "In this region the lavas which fill the ancient basin of the park rest upon the flanks of mountains formed of fragmentary volcanic ejecta, ... while the hydrothermal forces of the central portion of the park show but feeble manifestations of their energy in the almost extinct hot-spring areas of Soda Butte, Lamar River, Cache Creek, and Miller Creek." Although hot water no longer flows from these vents, "gaseous emanations are now given off in considerable volume." On Cache Creek, about two miles above its confluence with Lamar River, are deposits of altered and crystalline travertine, with pools in the creek violently effervescing locally. This is due to the copious emission of gas. Above these deposits "the creek cuts into a bank of sulphur and gravel cemented by this material, and a few yards beyond is the _débouchure_ of a small lateral gully coming down from the mountainside. In its bottom is a small stream of clear and cold water, sour with sulphuric acid, and flowing down a narrow and steep channel cut in beds of dark-gray volcanic tuff. Ascending this gulch, the sides, closing together, become very steep slopes of white, decomposed rock.... The only springs now flowing are small oozes of water issuing from the base of these slopes, or from the channel bed, forming a thick, creamy, white deposit about the vents, and covering the stream bed. This deposit consists largely of sulphate of alumina.... About one hundred and fifty feet above the main stream these oozing springs of acid water cease, but the character of the gulch remains the same. The odor of sulphur now becomes stronger, though producing no other effect than a slight irritation of the lungs.