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 mould, 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 Oreodon, an animal allied in some things to the camel and in others to the tapir family. Another animal of a tapir-like appearance, but called by geologists Lophiodon , also lived during this period, and left his bones in the muddy lake margins to become part of earth’s history. Also a peccary of large size, and an animal bearing some resemblance to the horse, called the Anchitherium ,—found also in France and in the Mauvaises Terres of Nebraska. The hipparion, or small three-toed horse, and a great number of cat-like, dog-like, and hyena-like animals, besides rabbits and squirrel-like creatures, belonged to this period, as their fossilized remains demonstrate.
Following this age was one of volcanic action and the outpouring of immense quantities of ashes and lava. By the lava-streams issuing from the Blue Mountains new barriers were raised, dividing the northern portion of the great lake of East Oregon more completely from the southern, which, by reason of superior drainage, was the first to become dry land. The lake on the northern side of the Blue Mountains, remaining longest a lake, continued to receive the drift of its shores for a longer period, and consequently offers a more perfect record of the changes which took place through all the Tertiary periods. Several of the strata formed in this lake are of pure volcanic ashes, still rough as pumice stone to the touch.
Thus this Middle Tertiary period was closed in violence. Volcanic fire, earthquake-shocks, and molten lava d
