THE MUD VOLCANO.
"This volcano, as is evident from the freshness of the vegetation and the particles of dried clay adhering to the topmost branches of the trees surrounding it, is of very recent formation. Probably it burst forth but a few months ago. Its first explosion must have been terrible. We saw limbs of trees 125 feet high encased in clay, and found its scattered contents two hundred feet from it."
On the east side of the Yellowstone, close to the margin of the river, are a few turbid springs, and mud-springs strongly impregnated with alum. The mud is yellow and contains much sulphur. These, the discoverers, Dr. Hayden and his company, called Mud-sulphur Springs. The main basin is 15 by 30 feet, and has three centres of ebullition, showing that deep in the earth are three independent orifices for the emission of heated waters. Dr. Hayden's description of the roaring spring issuing from a cavern, coincides with that given above. He called it the Grotto. Around all these springs he observed an abundance of grasses, rushes, mosses, and other plants growing with a surprising luxuriance. The recent mud-volcano described by Mr. Langford was considered by Dr. Hayden as the most remarkable mud-spring thus far discovered in the West.
"It does not boil with an impulse like most of the mud-springs," he says, "but with a constant roar which shakes the ground for a considerable distance, and may be heard for half a mile. A dense column of steam is ever rising, filling the crater, but now and then a passing breeze will remove it for a moment, revealing one of the most terrific sights one could well imagine. The contents are composed of thin mud in a continual state of the most violent agitation, like an immense caldron of mush submitted to a constant, uniform, but most intense heat.... All the indications around this most remarkable caldron show that it has broken out at a recent period; that the caving in of the sides so choked up the orifice that it relieved itself, hurling the muddy contents over the living pines in the vicinity."
The steam rising from this spring—the Giant's Caldron—can be seen for many miles in every direction. The movements of Muddy Geyser were closely watched for twenty-four hours by Mr. Campbell Carrington, who was specially detailed for that duty by Dr. Hayden. His observations began about nine o'clock A.M., July 1st. Then the pool was calm. Shortly after, he heard the loud, hissing noise of escaping steam. Hurrying to the geyser, he saw a wave about three feet in height rise and die away to the left; three similar waves followed in quick succession. Their dense columns of steam burst up to the height of twenty feet, with a dull, heavy explosion, the action continuing for fifteen minutes, when the spring ceased flowing as suddenly as it had begun. The average height of the flowing was about fifteen feet, though some of the jets reached fully thirty feet. Five minutes after the eruption the pool measured twenty-five feet in circumference and three in depth, where before it was a hundred feet in circumference and eleven in depth. Ten minutes later the mud began to rise slowly in the pool. This continued for a little over three hours, when the spring began to boil near the centre. The ebullition gradually increased in violence for twenty minutes, then it suddenly stopped, and the eruption began as at first. This rising, falling, and overflowing took place eight times in twenty-four hours. The following table shows the time of the observed flowings and their length:
"First flowing, 9.20 A.M. to 9.35 A.M.; length, 15 minutes.