No. 405.] REVIEWS OF RECENT LITERATURE. 771 
overlying the Laramie and beneath the earlier volcanics is here 
conspicuous and is believed to be of Eocene age. 
An interesting physiographic feature described by Mr. Hague is 
the old outlet of Yellowstone Lake, which formerly drained off to 
the southward by way of Snake River, and sent its waters to the 
Pacific. The outflow was through Outlet Canyon, south of the lake, 
and this gorge was so obscured by forest and glacial drift that for 
many years it was not suspected as being so important a key to the 
physiography. It is described as a “ broad, deep gorge, and through- 
out a long period of time evidently served as the channel for a rapid, 
powerful stream carrying a large volume of water. To-day its bot- 
tom is a flat, grassy meadow.” . .. An old terminal moraine across 
the bottom of the canyon marks the course of the present continen- 
tal divide. A mighty change was effected in late geologic times by 
the damming of the lake to the southward. and its overflow through 
the decomposed rhyolite on the north, so that the whole vast basin 
was diverted to form Yellowstone River and drain to the Altan- 
tic. The Yellowstone canyon and falls are results of this natural 
accident. 
Professor Knowlton’s study of the fossil flora, largely collected 
from the Tertiary tuffs and breccias, is a valuable contribution to 
paleobotany. Many species new to science are described, and it is 
shown that the present flora of the park is wholly distinct from that 
of Tertiary time.  * Climatic conditions must have greatly changed. 
The climate during Tertiary time, as made out by the vegetation, 
was a temperate or subtemperate one, not unlike that of Virginia at 
the present time, and the presence of the numerous species of Ficus 
would indicate that it even bordered on subtropical." 
The volume consists of goo pages of heavy paper, exclusive of 
plates, and there are 121 plates, in part map folders and thick helio- 
types. A book, 12 X 9 inches, of this thickness, is, to say the least, 
unwieldy, and it seems undesirable to bind together diverse material, 
by various authors, in such bulky tomes. The margins are unneces- 
sarily wide, and a book of this sort is extremely difficult to handle, 
and absolutely useless for the geologist in the field. As all the 
chapters are distinct in authorship, and the sequence is of no especial 
significance, such a work might much better be bound in a number 
of smaller volumes by separate authors. 
The microphotographs by Iddings are of unusual excellence, and 
most of the illustrations are good. The reconstruction of geologic 
cross-sections in the air (Pls. V, XXXII), for heights of 10,000 feet, 
