drained respectively by the Columbia and the Colorado rivers; but not until by deposits of various character the bottoms of these basins became sufficiently elevated.
In like manner, the later upheaval of the Coast Range caused to be inclosed between these mountains and the Cascade Range another immense body of water, which became fresh in time like the older lakes, and with the gradual elevation of the sedimentary deposits was finally drained off like them. That the dates of the formation of these lakes were widely separated is evident from the fossils of each, which indicate the geologic period to which they belonged; the deposits of the Wallamet Valley being the most recent.
In the meantime, vegetable and animal life flourished along the shores of these inland seas, or lakes. There are canyons in Eastern Oregon, fifteen hundred feet in depth, whose walls present a complete and undisturbed record of the geologic periods. First of all in this record is the old ocean-bed of the Cretaceous period, teeming with myriads of marine shells, perfectly preserved in form, though frequently containing, as a mold, a filling of chalcedony or calcareous spar, making specimens of the highest beauty.
Next above the salt-water deposits, come those of the earlier Tertiary periods. In this division, we find the leaf impressions of those grand trees that flourished during ages of tropical warmth and moisture: palms, yew-trees, immense ferns. In some places an oak-leaf, or an acorn-cup, has left its print in the rocks.
Contemporaneous with the palms and ferns were two species of rhinoceros, and three or four species of
