36 J. LeConte—Extinct Volcanoes about Lake Mono. 
former times. In any case, the lake waters are now but the 
concentrated residues of a much larger body of water, as plainly 
shown by the terraces to be presently described. During 
the process of concentration the less soluble lime carbonate has 
been deposited in strange irregular masses of calcareous tufa. 
These curious fungoid and coralloid masses, some of them six 
to ten feet in height, stand up thickly on the level shores and 
in the shallow marginal waters of the lake. Ata distance they 2 
look like the half-submerged stumps of a forest of gigantic 
This carbonate of lime deposit is evidently identical a 
t fe : 
trees. 
With the thinolite deposit deseri 
tmmoende oo ed lL, 
yt 
Kingt as occurring in 
such i quantities about the residual lakes of the Nevada a 
basin farther north, and which as he shows is a —— h 3 
itions under 
ever, slightly different from those in Nevada, and I believe 
quent paper. Farther east, near Columbus, Nevada, in the 
region of the dried-up lakes left at the extreme southern exten- 
* This Journal, IIT, v, 325. + Geol. Exploration 40th Parallel, i, 508, and seq. 
