GEOLOGY AND PALEONTOLOGY 
7 
tion. Volume hi goes into greater detail, comparing the 
condition of glaciers in 1899 with their condition as pre¬ 
viously observed, so as to infer changes, and making sys¬ 
tematic records of the positions of ice fronts, in order to 
facilitate future comparisons. It treats also of features 
tending to throw light on problems of Pleistocene glacia¬ 
tion in the eastern United States, discusses the Pleisto¬ 
cene glaciation of Alaska, and incidentally makes a con¬ 
tribution to earlier geologic history by describing certain 
peneplains belonging to the pre-Pleistocene topography. 
A noteworthy result in stratigraphic geology is the cor¬ 
relation, on fossil evidence, of slates and shales in three 
widely separated localities — Yakutat Bay, Prince William 
Sound, and Kadiak Island — and the determination of their 
age as early Jurassic. The formation or series thus con¬ 
stituted — named Yakutat by Russell — covers large areas, 
is elaborately and intricately folded, and is the domin¬ 
ant constituent of mountain masses which have a long 
history, including base-leveling and subsequent uplift and 
dissection. 
The Alaska Peninsula, which so bristles with volcanic 
peaks as to appear from a distance characteristically 
igneous, was found, at a point where narrowed by oppos¬ 
ing bays, to contain a ridge of uplifted marine strata of 
Eocene age. These strata contain a molluscan fauna, the 
first of that age discovered in Alaska, and show also, 
by their physical constitution, that the region was already 
the scene of volcanic activity in early Tertiary time. A 
collection of Eocene plants was also obtained from another 
point on the coast of the peninsula. 
The paleontologic collections include a number of new 
species, thirty-eight of which are described in this volume. 
Twelve are Jurassic and the remainder Eocene. Of the 
Jurassic species seven were found to be so peculiar as to 
require the erection of new genera. 
