Page:Centennial History of Oregon 1811-1912, Volume 1.djvu/239



state including the Coos Bay country and the valley of the Unipqua ; also an island extending northwest from Monroe to Albany, and the Nehalem and Tilla- mook coal fields.

THE MIOCENE AGE

The Oregon Eocene age drifted into Miocene time without striking topograph- ical changes. The broad, low basement of the Cascade mountains must have been growing for in addition to other evidence it is said that a large part of the deposits in which our Eocene age leaves were buried is fine volcanic ash, probably drifted from the volcanoes among the Cascade hills. If these fine particles fell in distant lakes of Oregon, Washington and Idaho, the "Cascade Barrier" must have already commenced that long period of vulcanism that slowly piled up ashes, cinders, bombs and lava into the grand mountain range of the future.

The land in the line of the Coast mountains was also becoming more elevated and of greater extent. A strip of Eocene sea bed was elevated into an island extending from near Monroe northward and including the hills west of Corvallis and Albany, where many characteristic Eocene shells are found.

The valley of the Umpqua was elevated above the sea level and the Calapooya mountains were probably connected with the present coast line by land of suf- ficient height to exclude the ocean from southwestei'n Oregon ; for Eocene shells are the latest positively identified in that region, except those found along the present ocean beaches. But the Miocene ocean still filled the Willamette valley with marine life, there were not only a great variety of shell fish, but seals must have been at home in these sheltered waters. The primitive seal of this period was quite different from modern forms and was perhaps an ancestral type from which the common seal, the sea lion, the walrus, and fur seal have since diverged. But life for these seals was not all sheltered peace, for there w^ere sharks in these same waters, some of their teeth have been taken from the old Miocene sea bed, now quarried for building stone, both in Polk county and at Eugene.

Eastern Oregon, Washington and Idaho was still a country of beautiful lakes with a warm, moist climate and luxuriant vegetation. One of the mysteries of our western geology is the sudden appearance in eastern Oregon of a most inter- esting and extensive fauna. By consulting a map of the Northwest it will be seen that the northern extension of the Wasatch mountains is the only barrier between Idaho and Wyoming. Now all through the Eocene there lived in Wyoming great numbers of strangely interesting Mammalian animals, while just west of these mountains in Idaho and the adjacent states of Oregon and Washington no Eo- cene mammals have been found. But the iliocene age dawns upon the descend- ants of these animals making themselves perfectly at home on the hills and marshy meadows that surrounded the large Pliocene lake that filled the John Day Valley. Many books might be written of these old "Oregon pioneers."

There was a primitive camel, the Poebrotheriura ; and they tell us the camel was originally a purely North American bred animal. One of the most formid- , able animals to be seen in those old Miocene woods was the Elotherium or Entelo- Idon. Of it Dr. Merriam, of Berkeley, writes.- "Probably few animals ever ex- listed better able to protect themselves than those huge Miocene boars." While