328 
ORIGIN OF LIFE IN AMERICA 
to. If a Pacific continent existed, and I quite concur with 
those who are of that opinion, it must have largely subsided 
before the Tertiary Era. It seems to me as if the central 
part of it had broken down gradually, the margins slowly 
following suit, both on the eastern and western Pacific, only 
leaving here and there a few remnants which either remain 
as isolated pillars far out in the ocean or have become joined 
to more recent land-masses. I imagine that the latest pre- 
Pliocene land connection between North America and Asia was 
not the Pacific Continent, but merely its margin, which per¬ 
sisted probably until Oligocene or Miocene times. In a geo¬ 
logical sense, remarks Dr. von Drasche,* it is more correct 
to draw the western boundary of the Pacific Ocean through 
Kamchatka, Japan, the Philippines, New Guinea and New 
Caledonia, because they all possess old crystalline or ancient 
sedimentary rocks. But the oceans, as Professor Walther f 
has pointed out, are areas of depression surrounded by folds or 
flexures which, give rise to extravasation of eruptive material. 
The chain of the volcanic Aleutian islands lie in such a fold. 
Near the east coast of Japan the depth greatly increases. On 
the eastern side of the Pacific, in western North America, 
the igneous rocks skirt the coast for some distance, whereas 
in the south-west the volcanic centres lay far inland, justi¬ 
fying the assumption that the Tertiary coast-line extended 
some distance inland, which is fully established by geological 
observation. Although the Pacific is known to have invaded 
Californian territory, there is no evidence that the coast hills 
and outlying islands were covered by the sea; and these pro¬ 
bably remained as part of the marginal land which skirted the 
west coast of North America. It is from this old land, I think, 
which contained Asiatic immigrants, that North America 
received its ancient Tertiary fauna from Asia. I suggest, 
therefore, that in early Tertiary times a belt of land, possibly 
representing the margin of the more ancient Pacific Continent, 
extended from the south-west coast of North America in a 
great curve to Japan and further south (see Fig. 14). The 
extraordinary similarity of the east Asiatic, Mesozoic and 
* Drasche, E. von, “ Palaeozoische Schichten auf Kamtschatka,” p. 268. 
t Walther, J., “ Tiber den Bau der Flexuren, &c.” 
