406 
TURNER. 
of the river gravels which now give evidence of the former 
existence of the river above mentioned. It could be also 
shown that the amount of faulting between the middle 
block, having its eastern escarpment along Little Grizzly 
Creek, and the eastern block, with its escarpment east of 
Thompson Peak, has been comparatively slight at the place 
where the river crossed the fault line. 
The highest gravel area observed which is ascribed to the 
ancient river lies about one mile north of Haskell Peak at 
an elevation of 7,000 feet. The most northern area observed 
lies to the east of Little Grizzly Creek and north of the 
fortieth parallel at an elevation of about 5,800 feet. The 
gravel deposits of this old river are well exposed by hydraulic 
washings at several points, particularly at the Cascade gravel 
mine. The river probably existed in Eocene and Miocene 
times. 
Mr. Diller informs me that he has traced the same chan¬ 
nel still further north, and that he believes the river to have 
had a northerly course. During a subsequent season I hope 
to get positive evidence as to the course of this ancient river 
and its bearing on the question of faulting. 
Professor Whitney believes the Sierra Nevada to have had 
substantially the same elevation in Tertiary times as now. 
(XVII, page 342.) 
He accounts for the large accumulations of auriferous- 
gravels in Tertiary times by supposing the precipitation, and 
consequently the volume, of water in the rivers to have been 
far greater at that time, and thinks that the present narrow 
and deep canons were cut by streams constantly diminish¬ 
ing in volume. 
In an excellent paper on “ The Ancient Biver Beds of the 
Forest Hill Divide ” (II, page 435) Mr. R. E. Browne gives 
the results of his investigations of certain channels in Placer 
county, California, which have been pretty thoroughly ex¬ 
posed by mining operations. He has been able to show that 
there are several channels of different ages, and has been 
able to map with absolute certainty portions of the courses 
