134 The American Geologist. Feb. 1891 
time, perhaps occasionally interrupted by dry climate and fall of the 
water, too low to maintain itsoutlet. 
Glaciers descending the canons on the west front of the Wasatch range 
attained their maxium extent, pushing their moraines into lake Bonne- 
ville, during the time of formation of the Provo shore-line. From these 
moraines and from those of Sierra Nevada extending iuto the Pleisto- 
cene area of lake Mono, the glaciation of the Cordilleran region is 
known to have been contemporaneous with the epochs of humid climate 
and extension of lakes in the Great Basin, the interlacustrine epoch be- 
ing attended probably with a nearly or quite complete departure of the 
glaciers and ice-fields on the mountains. 
Inquiring what were the causes of these great climatic changes, the 
author shows that a bodily uplift of the entire district, including the 
Great Basin and the adjacent mountains, would favor the growth of both 
lakes and glaciers, while conversely they would be diminished by de- 
pression of the district. Evidences of Pleistocene elevation of the land, 
corresponding to the glacial and lacustrine epochs, are found in the 
■deeply submerged channels near Cape Mendocino, which have been 
described by Prof. George Davidson of the U. S. Coast Survey. On the 
other hand, proofs of Pleistocene depression, referable probably to the 
time of temporary retreat of the glaciers and lowering or desiccation of 
lakes in the Great Basin between their two stages of high water, are 
supplied by the marine terraces of the Columbia and Frazer basins cited 
by Gilbert, and by the Pleistocene beds of theCalifornian coast recently 
described by Dall as rising gradually toward the south until at Monterey 
and southward they are about 600 feet above the sea level. 
Frequent eruptions of basalt have occurred within the area of lake 
Bonneville, the earliest belonging to the Tertiary era, long before the 
existence of the lake, others successively to the time between its first 
and second maximum stages, to the date of the Provo shore-line, and to 
the recent epoch since lake Bonneville was reduced to the Great Salt lake. 
Uplifting of the Wasatch range is shown to be still in progress by 
post-Bonneville fault scarps. Independent of these, a deformation of 
the area of the Pleistocene lake has taken place, by which its central por- 
tion is uplifted about 170 feet in comparison with its boundary ; and this 
deformation of the planes of the old shore-lines is regarded by the author 
as probably due to the drying away of the lake, the removal of this weight 
of water being attended by viscous distortion of the earth's crust. 
The last chapter of this valuable and very interesting monograph dis- 
cusses the age of the Equus fauna, which at its type locality is contained 
in lake beds that are correlated with the uppermost of the Lahontan and 
Bonneville beds ; and the conclusion is reached that this fauna, pre- 
viously called late Pliocene, is instead to be referred to a late stage of 
the Pleistocene or Glacial period. 
Preliminary Account of the Fossil Mammals from the White River 
and Loup Fork formations contained in the Museum of Comparative 
