56 Review of decent Geological Literature. 
Synopsis of the flora of the Laramie group. By Lester F. Ward. Pages 
399 — c;^7; plates xxxi — Ixv. (Accompanying the sixth annual report of 
the director of the U. S. geological survey.) 
The history of the discussions respecting the age of the Laramie group 
occupies nearly thirty pages at the beginning of this memoir. Lying 
between the previously recognized Cretaceous and Eocene systems, its 
flora is thought by Lesquereux and others to be most allied with the latter, 
while its fauna is closely related to that of the Cretaceous. With its 
representation of earlier and later phases respectively of animal and plant 
life, it supplies a bridge across what had been regarded as one of the 
greatest breaks in geologic time. 
The Laramie group is defined as an extensive brackish-water deposit 
situated on both sides of the Rocky mountains and extending from 
Mexico far into the British North American territory, having a breadth 
of hundreds of miles and representing some 4,000 feet thickness of strata. 
When this deposit was made, its area was an immense inland sea cut off 
from the ocean by intei-vening land areas, through which, however, it is 
believed that one or more outlets existed communicating with the open 
sea at that time occupying the territory of the lower Mississippi and 
lower Rio Grande valleys. This Laramie sea existed during an immense 
period of time and was finally but very gradually drained by the eleva- 
tion of its bed, through nearly the middle of which longitudinally the 
Rocky mountains and Black hills now run. The exceeding slowness of 
this event is shown by the fact, clearly brought out by Dr. C. A. White, 
that the marine forms of the underlying Fox Hills strata, as they grad- 
vially found themselves surrounded by a less and less saline medium 
on the rising of the intervening land area, had time to become trans- 
formed and adopted to brackish-water existence, while these new-formed 
brackish-water species, when the sea at length became a chain of fresh- 
water lakes, had time again to take on the characters necessary to fresh- 
water life. 
Remains of the vegetation of the Laramie age occur far more abun- 
dantly than do those of any of the other forms of life. In its swamps 
were formed extensive beds of peat, and its vast marshes were densely 
covered with cane, bamboo, and scouring rush, the thick accumlation^ 
of which are now preseved in its beds of coal, chiefly lignite. These are 
usually overlain by strata rich in fossil plant remains, showing that the 
rate of subsidence had then exceeded that of the growth of the deposit 
and the shallow sea had gained access, burying the last of the plants 
under its siliceous or argillaceous precipitations where they are pre- 
served. In numberless places the profusion of leaves is so great that 
there is too little rock between them to render it easy or even possible to 
separate them and obtain complete specimens. 
The presence of palms, Ficus, Cinnamomum, and other tropical genera 
in the southern portion of the Laramie area, while its northern portion 
has many species of Populus, Corylus, Viburnum, and other genera 
common to cold climates, indicates, as the author believes, a greater 
