108 



GEOLOGICAL SURVEY OF THE TERRITORIES. 



with twenty or thirty of these puffs, which are bursting each second, 

 tossing the mud in every direction on to the broad rounded rim. There 

 are several other mud-puffs in the vicinity, but they do not differ ma- 

 terially from the last, except in size. Within a few feet of the mud- 

 spring, there is a large clear spring, 40 by 60 feet, with perhaps fifty cen- 

 ters of ebullition, filled with the rusty leathery deposit, and all around 

 the basin where the waters overflow there is an extensive deposit of the 



iron. The temperature is 

 140°. About one-fourth 

 of a mile west of the large 

 mud-pots are some exten- 

 sive fissure-springs, one of 

 them 100 feet long and of 

 variable width, 4 to 10 

 feet. These appear to be 

 merely openings in the 

 g crust or deposit which 



< covers the entire surface. 

 ^ Quite a large stream flows 

 I from this spring. Many 

 g of the springs seem to re- 

 « main full to the rim of the 

 S crater, and are in a con- 

 ^^ tinual state of greater or 

 I less ebullition, and yet no 



water flows from them. 



Others discharge great 



quantities. The aggregate 



^ of the surplus water usu- 



Z ally forms a good sized 



1 stream, as is shown on the 

 '^ mai). In this group are a 



2 few springs that have pre- 



< cipitated a small amount of 

 ^ sulphur, the first observed 

 g in the Fire- Hole Valley. 

 ° (Fig. 40.) Silica and iron 

 I seem to be the dominant 

 ^ constituent in nearly all 

 > the deposits. There are 



numerous springs that de- 

 posit a curious black sed- 

 iment like |ine gun-pow- 

 der, and send forth a very 

 disagreeable odor. On 

 the southeast side of the 

 basin, it will be seen by 

 reference to the chart, that 

 there is a long group of 

 sj^rings extending high up 

 into the mountains. This is a most interesting group, and many of tbem 

 are of the largest size. There are not many geysers, and none of the 

 first class, yet nearly all of them are in a more or less intense state of 

 ebullition, shooting up a column of water varying from a few inches to 

 8 or 10 feet. Many of them are surrounded with a deposit tinged with 

 the b'^ightest of pink and rose tints from the oxide of iron. Theaggre- 



