82 DYNAMICAL GEOLOGY. 



In alkaline lakes, like Mono, immense quantities of 

 lime carbonate are depositing now, apparently from hot 

 springs containing lime, coming up in the bed of the lake. 

 These deposits take on curious coralline forms, which are 

 very characteristic. Similar rough coralline forms are 

 seen all about the margin and in the shallow water of this 

 lake, looking at a distance like the dead stumps of an old 

 forest. They show a greater extent of the lake at one 

 time than now. Immense deposits of a similar kind are 

 found in many parts of Nevada, and mark the places of 

 dried-away lakes (Fig. 42). 



