Firehole River, the main fork of the Madison, has its source in Madison Lake, a beautiful sheet of water set like a gem among the mountains, dense forests of pines coming down to the very shores. A pointed ridge extends into the lake on the west side about half a mile, giving it the form of a heart. Its area is about three miles from north to south, and two from east to west. Its shores are paved with masses of trachyte and obsidian. The high mountains about the lake and along the river are gashed with deep gorges, with steep and jagged sides. Pines grow upon the mountain-sides where the declivity is so great that they cannot be scaled. In the obstructed gorges and on the mountain-tops, from 9,000 to 10,000 feet above the sea, little lakes occur every mile or so, nestled among the pines. Clear-watered mountain-torrents tumble down the almost vertical ridges to swell the Firehole, making cascades that in any other region would enjoy world-wide fame. Just before reaching the geyser-basin, some ten miles below the lake, the river roars through a deep gorge in the trachyte rock, and as it emerges, dashes over two cliffs, one twenty, the other fifty feet in height. "These pretty falls," writes Lieutenant Doane, "if located on an Eastern stream, would be celebrated in history and song; here, amid objects so grand as to strain conception and stagger belief, they were passed without a halt." Shortly after, the cañon widens and the dominion of the Fire King begins. Scattered along both banks of the river are boiling springs from two to twelve feet across, all in active eruption. The craters of these springs are from three to forty feet high. Like the springs on Gardiner's River, these gradually seal themselves up by depositing mineral matter around and over their orifices. Numbers of such self-extinguished craters, now cones of solid rock, are scattered along the river-side. Two miles further down the stream is the upper geyser-basin, an open, rolling valley, two miles wide and three long, the mountains on either side rising 1,500 feet above the valley, with steep, heavily-timbered ledges of dark rock.