94 



EEPORT UNITED STATES GEOLOGICAL SURVEY. 



The following table gives the comparison of the temperatures taken 

 in the two years, and completes the list of springs in this locality : 



Name. 



Size. 



Tempera- 

 tures in 1871. 



Tempera- 

 tures in 1872. 



Yellow Sulphur Spring 



Locomotive Jet 



Steam Jet s, near Sulphur Spring 



Turbid Blue Mud Spring 



Blue Mud Pot 



Sulphur Spring (ea«it of hills) 



Sulphur Spring (in north part of hills). 



12 to 15 feet diameter 



Opening 6 inches diameter. 



45 feet by 60 feet. 

 4 feet by 10 feet.. 



°F. 

 183J to 197 

 191 



130 

 140 



178 



The deposits at Crater Hills are mainly siliceous, but sulphur is a 

 characteristic of many of the springs, and the springs therefore give acid 

 reactions. An analysis made in 1872 of a specimen from the Yellow 

 Sulphur Spring gave 3.23 per cent, of sulphur after 23.48 per cent, of 

 water had been expelled by ignition.* 



The surface surrounding the springs, at many places, consists merely 

 of a crust, and the under side as is shown on breaking it is coated with 

 crystals of sulj)hnr. Nearly all the springs give off sulphuretted hydro- 

 gen gas. The deposits of alum are due to the action of the sulphurous 

 waters upon the alumina and iron in the clay banks through which the 

 acid waters pass on their way to the surface. The small stream which 

 carries the water from these springs is strongly impregnated with alum. 

 This creek is known in the reports for 1871 and 1872 as Alu7n CreeJi, 

 but on the map of the Park in this volume the main stream of the valley, 

 which enters the Yellowstone a short distance below, is called Akim 

 CreeJc. On the map accompanying Comstock's report this is called 

 Warm Spring Creek. Iron is also present in the springs, as the weath- 

 ered deposits show ; the red stains on the white hills being one of the 

 characteristic appearances. The area occupied by the remains of ex- 

 tinct springs is much larger than that occupied by those that are now 

 active. 



On the east side of the Yellowstone, opposite Crater Hills, there are 

 sulphur springs along the edge of the hills, but none of any importance 

 until the mud volcanoes are reached. They are not indicated on the 

 map. 



MUD VOLCANOES OE MUD SPRINGS, 



This locality, which is designated on the maps as Mud Geysers, is 4 

 miles below Yellowstone Lake and 6 miles from Crater Hills. It is the 

 point from which Howard's wagon road starts for the East Fork of the 

 Fire Hole or Madison Eiver. Its name designates the character of its 

 springs and salses. The name " Mud Volcanoes" is taken from the fact 

 that one of the principal springs here is the Giant's Caldron or Mud Vol- 

 cano. Besides this there are a number of mud springs with craters like 

 miniature volcanic craters. Besides the Mud Volcano there is here a 

 muddy sulphur geyser, which is the first geyser met with by parties en- 

 tering the region via Bozeman Botteler's and the Mount Washburn route. 

 I prefer to keep the name by which I designated the locality in 1871 and 

 1872. 



The springs occupy an area of about three acres, and are found in 

 ravines and gullies cut into sandstones which were deposited when Yel- 

 lowstone Lake spread over the entire area of Hayden's Valley. 



These at the base are rather coarse, as shown in the exposures along 



*Eeport for 1872, p. 137. 



