Geology and Mineralogy. 67 
rwas published. The result of this investigation has been to cor- 
r 
-calls the feldspars in certain rocks, sanidin, when they are really 
Shasta and Lassen’s Peak, and the announcemen 
t de 
they are andesitic volcanoes, not a single trachyte being included 
. . . 
to notice further, is a series of ‘‘ Accompanying Papers” as follows: 
rica, by C. A. White. 
rof. Marsh in his paper gives a résumé of his investigations of 
pec The basin of Lake Lahontan, a Quarternary lake of 
characterizing three distinct deposits in the basin. They are— 
designated, in the order of their age, as lithoid, thinolitic, and den- 
dritie. The first of these reaches the level of the lithoid terrace 
feet. The third and most abundant ‘of all the chemically formed 
rocks of the basin, is the dendritic tufa, which is locally twenty 
feet and possibly fifty feet thick, and extends about 300 feet 
