132 The American Geologist. February, 1901. 
the path of the glacier wliich lias not been able to destroy or seriously 
erode it. 
Prof. A. C. Lawsoii presented a series of arguments drawn from 
the superficial structure of the region tending to show that the elevation 
of the Sierra Nevada was in date later than that of the Coast ranges. He 
argued that the river-valleys of the two regions presented marked dif- 
ferences — that the drainage in the Sierra Nevada is consequent and 
the system therefore immature, while in the Coast range the drainage 
is subsequent and the geomorphy mature. Illustrations were drawn 
from the branches of the Klamath, Eel and Sacramento rivers in sup- 
port of the views advocated in the paper. 
Prof. Lawson also spoke briefly on a specimen of feldspar-bearing 
corundum, from Plumas county, California, which occurs as a dyke 
cutting serpentine on the eastern flank of Spanish peak. He spoke of 
the rocks as supersaturated with alumina, and said, the feldspar was 
an oligoclase containing by an analysis 16 per cent of corundum. 
Prof. J. C. Merriam, of Berkeley, spoke of the John Day beds ex- 
posed on the river of the same name. The canyon is cut through an 
immense series of strata about 10,000 feet in thickness and ranging 
from the Jurassic to the Quaternary and composed of nine or ten dis- 
tinct beds. These include large quantities of volcanic tuffs and ashes, 
with andesitic and rhyolitic lavas lying on the John Day beds and 
tilted with them to an angle of 30** over which are seen 1,500 feet of 
Columbian lavas. The abundance of land shells of such genera as 
Helix, the scattering of the bones of the skeletons and the absence of 
fish remains were mentioned as tending to cast some doubt on the 
lacustrine nature of the deposit. Ten skeletons have been found whole 
and very few. plant remains occur. The Cretaceous beds are of the age 
of the lower Chico. 
Mr. H. M. Turner, of Washington, D. C, spoke on the Geology of 
the Great Basin in California and Nevada. The address was illustrated 
with lantern slides. The ridges of the western edge of the Great 
Basin in Nevada and eastern California, are usually very complex in 
structure and composition. They comprise sediments of Paleozoic 
and Juratrias age much disturbed at some points by intrusions of 
granolytes. In Tertiary time there were extensive lakes, and con- 
temporaneous with these lakes, and also later, lavas and tuffs 
in large amount, chiefly rhyolytes, andesytes and basalts. The for- 
mation of the ranges or at least their latest uplifts date from the 
Tertiary or post-Tertiary. They were elevated along normal faults, 
the valleys being subsided areas, often of the nature of rock basins, 
whose rims are made up of rocks older than the desert detritus. 
There are some gneisses pretty certainly of pre-Cambrian age. 
These gneisses underlie lower Cambrian slates and limestone There 
is an extensive chert series rich in graptolites supposed to be of lower 
Silurian age. There arc also lower Trias beds in the Inyo range and in 
the Pilot mountains Jurassic limestone and slate. The Tertiary lava 
beds contain abundant plant, molluscan and fish remains. 
