GEOLOGY. 333 



here, lie says, is difficult of description, and the effect can only be known by 

 one who has heard the wild rush of steam, the rude sounds of the mud ex- 

 plosions, and the dull murmur of the boiling cauldrons of slime. The space 

 occupied by the Salses is a parallelogram, 500 yards long and 350 broad a 

 table of hardened bluish clay, a little elevated above the surrounding plain. 

 The adjacent ground is low and muddy, and during the rains is entirely cov- 

 ered with water. There is a gentle slope towards the north and east, the 

 mud and water of the Salses running off slowly in that direction, where a 

 lake of salt water exists in the rainy season, but presenting now a vast sheet 

 of crystalline chlorid of sodium. Into this lake the arm of the Colorado, 

 known as New River, discharges itself. The lake, having no outlet, would 

 probably soon regain its ancient area if the channel of New River afforded a 

 regular and more generous supply of water. 



The steam-jets of the Salse issue from conical mounds of mud varying 

 from three to fifteen feet in height, the sides presenting various angles, some 

 being sharp and slender cones, others dome-shaped mounds that seem to 

 have spread and flattened out with their own weight, upon the discon- 

 tinuance of the action that formed them. Out of some of the cones the 

 steam rushes in a continuous stream, with a roaring or Avhizzing sound, as 

 the orifices vary in diameter or the jets differ in velocity. In others the 

 action is intermittant, and each recurring rush of steam is accompanied by a 

 discharge of a shower of hot mud, masses of which are thrown sometimes 

 to the height of a hundred feet. These discharges take place every few 

 minutes from some of the mounds, while others seem to have been quiet for 

 weeks or months. During our short stay we had specimens of the rapidity 

 with which a sharp, conical mound could be built up and again tumbled 

 down. In one place a stream of hot water was thrown up from fifteen to 

 thirty feet, falling in a copious shower on every side, forming a circle within 

 which one might stand without danger from the scalding drops, unless the 

 wind chanced to drive them from their regular course. It issued from a su- 

 perficial mound, out of an opening about six inches in diameter; but the 

 column of steam and water, immediately upon issuing, expanded to a much 

 greater size. The orifice was lined with an incrustation of carbonate of lime, 

 and around it, and particularly on the southeast side, stood a miniature 

 grove of slender stalagmitic arborescent concretions of the same substance. 

 They were from half an inch to one and a half inches in diameter, and from 

 four to eight inches in height. Many of them were branched, and the tips 

 colored red, contrasting beautifully with the marble-whiteness of the trunk, 

 and resembling much a coral grove. Some were hollow, and delicate jets of 

 steam issued from their summits, and this seemed to explain the mode of 

 their formation. Some were not hollow throughout, being closed at the sum- 

 mit ; but when detached from their base, a small orifice in the centre suffered 

 hot steam to pass, and some degree of caution was required to remove them 

 without scalded fingers. To approach the spot was a feat of some difficult}', 

 surrounded as it was by a magic circle of hot rain. I retreated, scalded, 

 from the only attempt I dared to make ; but my son, more adventurous, or 

 more attracted by the beauty of the specimens, succeeded in bringing away 

 several. The falling water ran off into a pool a foot deep, but what became 

 of it was not apparent, as it had no seeming outlet. I brought away a bot- 

 tle of it for examination. It was transparent, but had an intensely bitter 

 and saline taste. A little beyond, on either hand, are two huge cauldron-like 

 basins, sunk five or six feet below the general level, and near a hundred feet 



