Sept. 12, 1872] 



NATURE 



399 



uncommon, and are at some seasons of the year very- 

 severe. 



Yellowstone Lake itself has at all seasons the tempera- 

 ture nearly of cold sprin;^- water, and its area is gradually 

 but vcr\- slowly diminishing. Mr. Hayden estimates thit 

 since the period of volcanic activity the depth of the lake 

 has been .about 500 feet greater than at present, the shore 

 line having then been high up on the sides of the sur- 

 rounding mountain?. 



Warm springs are not uncommon in the valley of the 

 lower Yellowstone, but the temperature is seldom higher 

 than 60° or So°. It is not until we reach Gardiner's 

 River, a small branch flowing into the Yellowstone on the 

 left side, opposite the third canon, that the true hot springs 

 commence in their full force. About three miles above 

 its junction with the Yellowstone, the valley bottom is 



covered with a thick calcareous crust, the deposits of hot 

 springs which are now extinct ; but llowing swiftly from 

 beneath this crust is a stream of hot water six feet wide 

 and two feet deep, with a temperature of 132°. A little 

 distance farther up is a high hill, on the slops 

 of which has been formed a system of terraces, each 

 from 200 ft. to 300 ft. in height, and covered with a thick 

 deposit of lime. On the ascent of the hill, about three- 

 fourths of a mile from the river bottom, there is to be 

 met with one of the most remarkable exhibitions of hot 

 spring deposits that is to be seen in this land of wonders. 

 In the distance it looks like a vast glacier of snow and 

 ice, on which account it has been named the White 

 Mountain. Indeed, the different terraces can be com- 

 pared, for their wonderful beauty, only to a frozen cascade. 

 The remains of once active springs are plainly visible ; 



Fig. 3. — Sulphur and Mu J Springs, Six Miles below ihe Lake. 



old chimneys, irregular opening3,like entrances to caverns, 

 which extend beneath the crust, are numirous. This 

 crust is probably from 20 ft. to 50 ft. in thickness, and 

 undcrneith it is supposed that the surplus water from the 

 active springs above flows down to the river. A little 

 f.irther up is a series of basin-like pools, from 4 ft. to 8 ft. 

 in diameter, and on a terrace about 200 ft. farther still 

 are numb .;r3 of active springs, with basins 20 ft. to 50 ft. 

 in diameter, some of them with several centres of violent 

 eouilition in the sam? basin. The temperature at the 

 outflow varies from 150' to 162". 



Upon the terrace, down about midway on the side of 

 the mountain covered with this deposit, the principal 

 active springs are now located, and here is pre- 



sented another picture to the eye which tran3cen;ls 

 any description in words. Th; water is pjrfc;tly trans- 

 pirent, and dovn in the clear depths cm be seen dis- 

 tinctly the minutest orni'iieat upjn the inner sides of the 

 basin ; ani the exquisite bjiuty of the colouring and 

 the variety of forins bitfle any attempt to portray them, 

 either with pen or pencil ; various shides of red, fro n 

 the m)3t brilliant scarlet to light purple; yellow, from 

 deep-b;ight sulphur thrju^h all the shades to light creim 

 colour ; and green of various shades. These springs also 

 are full of a kind of vegetation, which under the micro- 

 scope proves to be composed of diatoms, among which Dr. 

 Billings discovers Palin:lLi and Oscillaria. There are 

 also in the quiet springs, ani in the little springs that flow 



