REVIEWS AND BOOK NOTICES. i {ao 
“ We may conclude, not only that the carving out of the chan- 
nel of the Grand Cañon was a very modern event, but that the 
deposition of the entire material which forms the cañon is, in a ge- 
ological sense, quite a modern occurrence. The drainage of the 
country commenced long before the excavation of the present water- 
courses, but it is difficult to answer the question how this great 
drainage was brought about, unless we account for it by a general 
elevation of the entire country, gradually sending this immense 
body of water, which must have prevailed all over the northwest 
_ at least, perhaps all over the Rocky Mountain region, westward 
into the Pacific and eastward into the Atlantic. As the waters 
slowly subsided they were separated into lakes of greater or less 
size, and then came the excavation of the Grand Canon, which 
slowly drained the great lake-basin above the falls so that now 
we have only the comparatively small remnant, the Yellowstone 
Lake. Other small fragments are scattered about in the vi- 
cinity, which now form reservoirs for the local drainage. Un- 
doubtedly the same series of remarkable physical events occurred 
in Oregon and California and in Idaho and Washington Terri- 
tories, and, perhaps, far southward into Mexico, judging from the 
published reports. The Hot Springs, which are now slowly dying 
out, are, of course, the last of this series of events. The evidence 
seems clear that all over the West, during this great period of vol- 
canic activity, the hot springs and perhaps even geysers were very 
numerous. We everywhere find the remains or deposits in all the 
states and territories west of the Mississippi, and now and then 
a warm or hot spring remains to indicate the story of their former 
power.”’ 
How these valleys were eroded may be inferred from the fol- 
lowing remarks. ‘On the west side of the Madison there are three 
mountain-gorges we see the sources of the myriad small branches 
which, in the aggregate, form the large river. Nestled among the 
craggy cliffs are here and there little ponds of clear water, derived 
from the melting of the snows, seldom ever seen except by the 
birds and the game that visit them to quench their thirst. The 
tendency of all these gorges is to work their way inward toward 
the divide. Great masses of snow and ice accumulate in them 
during the winter ; and the water, flowing down among the fractured 
_ Masses, freezes and expands with a force that year by year tears 
_ down a portion, which falls into the depths below and is swept down 
or four peaks which are at least 10,000 feet high. Among these s 
