93 
The continental deposits which have furnished these most interesting 
plants are not continuous, but represent basin deposits whose lower and 
upper limits probably do not exactly coincide from basin to basin any 
better than do the similar basin deposits throughout the western United 
States. The fossil plants, which are so abundant at some of the localities, 
flourished under somewhat different environments, according as they were 
subject to the humid winds from the Pacific ocean, with its warm currents, 
as was the Puget flora; or had this oceanic, moist, and generally equable 
climate modified by distance from the sea and by intervening topography. 
The plants described in the following pages are distinctly temperate 
types. Opinions differ as to the interpretation to be put on them, but I am 
inclined to consider them as indicating cool rather than warm temperate 
conditions, with abundant moisture. They are certainly in striking contrast 
climatically with the contemporaneous floras of the southeastern United 
States, and they mark about the southern limits of this essentially conifer- 
ous — hickory, oak, birch, alder, hazel — flora, that extends from the neighbour- 
hood of the present International Boundary, northward throughout the 
lands of the Arctic, and constitutes the so-called Arctic “Miocene” flora, 
which is known to be really much older, and, in all probability, Upper 
Eocene. 
These northern floras were probably enabled to flourish north of their 
existing northern limits by reason of the cumulative climatic effect of the 
restricted land areas of the Middle Eocene and the expanded equatorial 
oceans of that time, and the free water circulation from the latter north- 
ward. This was interrupted at the close of the Eocene, as the record of 
terrestrial plants and animals unite in proving, and was never renewed to 
the extent that it had had previously. This is one of the most cogent 
reasons for regarding all of these northern Tertiary floras as pre-Oligocene, 
irrespective of their particular facies. 
An interesting feature of the flora described in the following pagesj 
and of the Kenai flora as well, one that cannot be precisely evaluated at 
the present time, is the strong resemblance of many of its members to exist- 
ing types of eastern Asia, particularly those of the mountains of central 
China, which last region is coming to be recognized as a sort of immense 
pre-Pleistocene floral retreat. The genera Ginkgo and Glyptostrobus, so 
common in the Canadian Eocene, survive only in that region: the so- 
called Carpinus grandis of this report is close to the existing Carpinus 
seemeniana Diels of central China; Alnus cremastogynoides is much like 
Alnus mastogyne Burkill of the same region; Corylus macquanrii , in some 
of its forms is very similar to the restricted Chinese genus Ostryopsis, 
others are much like the existing Corylus colurna Linnaeus, and others like 
Corylus ferox Wall., both Asiatic; the fossil genus Trochodendroides appears 
to represent the restricted eastern Asiatic family Trochodendraceae; and 
most of the remaining genera, notably Taxodium, Liriodendron, and 
Sassafras, represent types which survive at the present time in only south- 
eastern Asia and southeastern North America, or in some few cases, as 
for example Sequoia, in the Pacific Coast region. 
10277—7 
