GEOLOGICAL SURVEY OF THE TERRITOEIES. 181 



the thick, blue mud in a state of violent agitation, sometimes throwing 

 it to the height of 15 or 20 feet. This mud contained — 



Sulphate of iron and alumina, 



Sulphate of magnesia, 



Chloride of magnesium, 



Alumina, 



Sulphur, 



Silica. 

 Near these mud-craters there were also some alum-pools containing 

 alum and sulphur. On the edges of these pools there were a number 

 of holes, from which there was a bubbling of water that flowed into the 

 springs. Upon ascending the hill, at whose base these springs were 

 situated, we could see immense volumes of steam rising toward the 

 southeast. Proceeding in that direction about 400 yards we came to a 

 sort of a cave in a sandstone rock. The entrance is about 15 feet high, 

 and it gradually slopes inward for about 20 feet. At this point, at regu- 

 lar intervals of a few seconds, there bursts forth a mass of steam, with a 

 pulsation which shakes the ground, while a stream of clear water flows 

 from the mouth of the cavern. Its temperature was 184° F. The 

 water had a very faint alum taste, and gave off a slight odor of sul- 

 phureted hydrogen. This S])riug we named the Grotto. A little far- 

 ther on, after passing a large muddy sulphur pool of about 20 feet in 

 diameter, we found on the side of the hill a huge mud-crater. Its orifice 

 is circular and from it there escapes a dense volume of steam, obscuring 

 for the greater part of the time the view of the boiling mass of mud, which 

 is 20 feet below the surface. It was too deep for us to determine its tem- 

 perature. The mud seems to be very thin and of a blackish color. Some 

 of the mud from the rim of the crater contains alumina and silica, with a 

 ; little iron, lime, soda, and potassa. It is jjiobably a true mud-geyser, for 

 the appearance of the crater and the trees around it would indicate that 

 at times it ejects its contents to a considerable height. The trees within 

 200 feet of it are coated with dri.ed mud even to their topmost branches. 

 During our stay, however, it had no eruption. About three hundred 

 yards southeast of this crater we discovered another muddy geyser. 

 The basin of this geyser was about 50 feet in diameter, and situated in 

 a basin circular in shape, containing two other springs. Its tempera- 

 ture was 191° F. The trapper who was with us, and who had visited 

 the place before, assured us that about 6 o'clock p. m. it would com- 

 mence spouting. ^We waited somewhat incredulously, for the spring 

 was quite placid. Soon, however, there began a slight bubbling in the 

 center, and the water began to rise gradually in the basin until sud- 

 denly it was thrown into violent agitation, the contents becoming very 

 muddy. Immense volumes of steam escaped, throwing the water to 

 the height of 20 feet. The eruption lasted about a quarter of an hour, 

 when it ceased as suddenly as it began, and the surface of the water 

 was more placid than before. This eruption took place eight times in 

 twenty- six hours. These salses, or mud -volcanoes, are known to all vol- 

 canic regions. They are found in South America, in Italy, in Java, in 

 New Zealand, and in Iceland. We found them always where the water 

 w^as obliged to pass through a bed of clay. In the last group I have de- 

 scribed, in one case, that of the " Grotto," the water came through sand- 

 stone and was ijerfectly transparent and clear. Had it been situated in a 

 bed of clay it would probably have been a mud-spring. In all of these 

 we found sulphureted hydrogen gas to a greater or less degree, and 

 they were all impregnated with alum. The sulphureted hydrogen is 

 probably decomposed, losing its hydrogen. The sulphur, becoming 



