J. LeConte—Old River-beds of California. 189 
hus it seems to me that the four questions suggested by the 
phenomena of the old river beds and their fillings, have been 
hot only each answered, but they have been all connected 
together in a satisfactory manner. 
Sequence of Events. 
_It may be well to briefly recapitulate the main points of my 
view, by narrating rapidly the events in the order of their 
uence 
Immediately after the birth of the Sierra Nevada, at the 
nning of the Cretaceous period, a drainage system com- 
menced to be formed. This system we may be assured 
S10n slowly progressed. Then commenced the glacial cold at 
the end of the Pliocene, a rising of the Sierra region, and the 
oi some Ancient Glaciers of the Sierra. This Journal, vol. v, p. 325, 1873, and 
Vol. x, p. 126, 1875, ‘ 
Am. Jour. Sc1.—Turrp sie Vou. XIX.—No. 111, Marcu, 1880, 
