SPRINGS AND GEYSERS 



would hi- thrown depends upon the amount of steam, the size and 

 >trui.u r litnr>s of the tube, etc. 



It is clear that everything which impedes convection in the 

 geyser tube will hasten the 

 period of eruption, since im- 

 peded circulation will have the 

 effect of holding the hot water 

 down, and so of bringing the 

 water at some level below the 

 top more quickly to boiling. 

 It follows that anything which 

 chokes the tube, or which in- 

 creases the viscosity of the 

 water, hastens an eruption. 1 



Some geysers build up 

 crater-like basins or cones 

 30 to 32) about them- 

 selves, the cone being of mate- 

 rial deposited from solution 





ilia 



Fig. 30. The cone of Lone Star Gey- 

 ser, Yellowstone National Park. (U. S. 

 Geol. Surv.) 



(? 3?)- The brilliant colors 



of' some of the deposits about 



the springs in the Yellowstone Park are attributed to the little 



plants which cause the deposition. When the water from any 



geyser or hot spring ceases to flow, the plants die and the colors 



disappear. 



The heating of geyser water must cool the lava or other source 

 heat below. As this takes place, the time between eruptions 

 ;comes longer and longer. In the course of time, therefore, the 

 geyser must cease to be eruptive, and when this change is brought 

 about, the geyser becomes a hot spring. Within historic time 

 :veral geysers in the Yellowstone Park have ceased to erupt and 

 lew ones have been developed. There are something like 3,000 

 r ents of all sorts in this park, hot springs which are not eruptive 

 greatly outnumbering geysers. 



A few geysers have somewhat definite periods of eruption. Of 

 such "Old Faithful" is the type; but even this geyser, which 

 formerly erupted at regular intervals of about an hour, is losing the 

 reputation on which its name was based. Not only is its period 



I eruption lengthening, but it is becoming irregular, and the 

 1 Weed. Am. Jour. Sci., Vol. XXXVII, 1889, pp. 351-59. 



