100 REPORT UNITED STATES GEOLOGICAL SURVEY. 



IS". P. Langford, speaking of the change from 1870 to 1872, says: 



Tlie jet of the Mnd Geyser was thrown with greater force [in 1870] and to a loftier 

 height, and its basin, but partly filled in 1870, now overflowed whenever an explosion 

 occurred.* 



I am inclined therefore to think that there has actually been a de- 

 crease. 



Gianfs Caldron or Mud Volcano. — This is perhaps equally interesting 

 with the Mud Geyser. Its crater or excavation is about 25 to 30 feet 

 in diameter and 20 to 30 feet deep, situated on the slope of a wooded 

 ravine. The deposit surrounding it is a dark gray mud, consisting mainly 

 of alumina. The contents consist of thin blackish mud in a state of 

 constant ebullition, and from its surface a column of steam escapes 

 with such volume that it can be seen for miles. This mud spring has 

 given name to the locality, and was first seen by the Washburn party 

 of 1870. I shall give the descriptions chronologically, as in the case of 

 the Mud Geyser. 



1870. — Lieutenant Doane describes the Mud Volcano as follows : 



Heavy volumes of steam escaped from the opening, ascending to the height of 300 

 feet. From far down in the earth came a jarring sound, in regular beats of five seconds, 

 with a concussion that shook the ground at 200 yards distant. After each concussion 

 came a splash of mud, as if thrown to a great height; sometimes it could be seen from 

 the edge of the crater, but none was entirely ejected while we were there. Occasion- 

 ally an explosion was heard like the bursting of heavy guns behind an embankment, 

 and causing the earth to tremble for a mile around. These explosions were accom- 

 panied by a vast increase of the volumes of steam poured forth from the crater. This 

 volcano has not been long in operation, as young pines, crushed flat to the earth under 

 the rim of mud, were still alive at the tops. The amount of matter ejected was not 

 great, considering the power of the volcano. The distances to which the mud has been 

 thrown are truly astonishing. Directly above the crater rises a steep bank, a hundred 

 feet in height, on the apex of which the tallest tree near is 110 feet high. The top- 

 most branches of this tree were loaded with mud 200 feet above, and 50 feet laterally 

 away from the crater. The ground and fallen trees near by were splashed at a hori- 

 zontal distance of 200 feet. The trees below were either broken down or their branches 

 festooned with dry mud which appeared in the tops of trees growing on the hill- 

 side from the same level with the crater, 50 feet in height, and at a dist-mce of 180 

 feet from the volcano. * * * It was with difficulty that we could believe the 

 evidence of our senses, and only after the most careful measurements could we realize 

 the immensity of this wonderful phenomenon. t 



1871. — We had no difficulty in recognizing the Mud Volcano in 3871. 

 A dense column of steam constantly escaped from the orifice, and it was 

 only when a puif of wind blew it aside that we could look into it and see 

 the seething contents, 30 feet below the surface. No eruption took 

 place during our stay. The steam poured forth with a steady roar. 

 The coating of the trees with mud was noticed, and small pines were 

 seen still alive within 10 or 20 feet of the orifice. We still supposed 

 that eruptions of mud occurred, but concluded that they must occur at 

 long intervals. 



1872. — The Mud Volcano appeared to be in much the same condition 

 as in 1871. Mr. Langford, who had not seen it since 1870, however, 

 saw great changes in it. He says : 



The crater, which in 1870 was in a state of constant ebullition, the report which 

 resembled the noise of distant artillery, the cone which had been builded by a constant 

 accretion of varied deposits, all had disappeared. A large excavation remained, and a 

 seething, bubbling mass of mud, with several tree-tops swaying to and fro in the midst, 

 told how terrible and how effectual must have been the explosion which produced 

 such devastation. I could not realize that in this unsightly hole I beheld all that was 

 left of the rarest of those physical wonders which filled this extraordinary region.^ 



* Scribner's Magazine, Vol. VI. 



t Yellowstone Expedition of 1870. Senate Ex. Doc. No. 51, 41st Congress, 3d session^ 

 pp. 17, 18. 

 t Scribner's Magazine, Vol. VI. 



