Geological Notes on the Sierra Nevada. — Turner. 243 
tained by the Pleistocene gulf waters. The Pleistocene shore 
gravels have been proved at many points auriferous. They 
have been extensively washed on the plateau southwest of 
Camanehe, and also along- the Mokelumne near Camanche, at 
the North Hill mine near Jenny Lind, at Irish Hill, and other 
points. 
The river deposits of early Pleistocene age consisi of gravels along the 
present rivers lying usually less than one hundred feel above the presenl 
river level. There is much more variety in the pebbles of these gravels 
they having been formed chiefly from the hard pre-Cretaceous nicks, in 
which the river canyons are cut. The early Pleistocene river gravels 
have, as a rule, proved highly auriferous. Some of the Pleistocene 
streams have changed their courses tor short distances, having cut 
through some harrier. This is the case with the Mokelumne river, 
mile west of Lanclia Plana, on the Jackson sheet, and also with Slate 
creek, on the Bidwell Bar sheet, just before it joins the Yuba river. 
The gravels in the deserted beds of both of these streams have been 
mined for gold. 
Some of the valleys of the range were occupied in early Pleistocene 
time by lakes. This is the case with Mohawk valley- in Plumas 
county, and with Meadow valley, at the head of Spanish creek. The 
fake in Mohawk valley was caused by the waters of the Feather river 
being dammed back by an eruption of andesite-breccia, while the basin 
of Meadow valley appears to have been formed bj orographic causes. 
The gravel-benches aboul Meadow valley thai were formed bj this'early 
Pleistocene lake, attain an altitude of more than 4.0(10 feet, the lowest 
part. of the valley having an altitude of 3,700 feet Sierra valley was 
doubtless formerly occupied by a shallow sheet of water. 
Moraines are ver\ abundant and finely preserved in all that portion of 
the range where the higher points attained an altitude of 8,000 feet or 
more. The glaciers were local and with onlj minor exceptions they 
followed "the course of the presenl drainage system. Thej evidently at- 
tained their maximum development after the formal ion of the present 
canyons. As was stated bj Prof. I.e. Russell, \ there are rudimentary 
glaciers still in existence in the high Sierra region east of Ybsemite 
valley. One of the most easily seen of these was visited l>\ the writer. 
This is on the north side of Mi. Dana. There is here a verj prettj cres- 
cent-shaped terminal moraine, and the water of the little lakes below 
I he glacier is yellowish from the sill, presumably due to I he erosive ac- 
i ion of the glaciers. 
Prof. Joseph Le Conie| has studied the glaciers ai Mono lake and lake 
Tahoe. 
•Bull. Phil. Soc. of Washington, vol. 11, pp. 385-410. 
IKi.e-hth Annual Report, U. S. Geol. Survey. Pari I. 
JAin. .lour. Sri.. 3d Ser., vol. 10, pp. 126-130. 
