Page:Centennial History of Oregon 1811-1912, Volume 1.djvu/247



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even this thin covering has been blown away, leaving the bones exposed to the summer sun or winter snow. They will be highly prized as a nucleus for a high school museum or gladly received at the State University, for the dishonest gi-eed of an Eastern scientist has left Oi'egon without any collection of bird bones, which are so rare among fossils that an eminent paleontologist has spoken of these from Fossil lake and the Cretficeous birds of Kansas, as being the only fine collections of fossil birds in the United States.

In this Fossil lake region many mammal bones have also been found, includ-- ing three species of the modern one-toed horse and a great sloth-like animal as large as the grizzly bear, called the mylodon. There were also bears, coyotes, rabbits, gophers, otters, beavers, a mammoth elephant and at least four kinds of camel, ranging in size from a modern camel to the smaller auehenia. Most of these animals have also been found in a narrow lake in the Upper John Day val- ley, although bird bones are there extremely rare.

During the Pliocene age, especially near its close there was great activity in mountain building on our coast, not in the elevation of new ranges, for the Cas- cades and Sierra and the Coast mountains were all in place, but upon the broad dome-shaped basement story of the Cascades a grand super-structure was now built up, for it is to the Pliocene we owe much of the grandeur of the Cascades and High Sierra mountains. For their lofty summits, their towering peaks and castles, their volcanoes and grand snow peaks we are largely indebted to the Plio- cene and the following Pleistocene period.

We have noted the great outpouring of lava from cracks or fissure eruptions and that the fine ashy sediments in which the Eocene' and Miocene leaves were buried is proof that volcanoes then existed, probably in the Cascade and Cali- pooya mountains; but the Oregon portion of the Cascade range was then not of sufficient elevation to obstruct the ocean breeze in its progress toward eastern Oregon. The moisture-laden clouds had kept the lake shores and hillsides green with rich and luxuriant forest even to the close of the Miocene. But during the Pliocene all this was changing, the Cascade mountains were becoming a lofty mountain range, the climate was cooler, eastern Oregon and Washington were being ti-ansformed into a high table land and a fine grazing country, over which roamed herds of wild horses and camels. But the luxuriant forests were slowly retreating toward the south. For the whole North Temperate Zone was being elevated and the cold of the glacial period was gradually creeping over the land.

THE PLEISTOCENE AGE

When finally the Pliocene had passed and the Pleistocene with its glacial pe- riod had covered most of our northern states with a sheet of ice and snow, "Ore- gon was not under a continuous mantle of ice but had many independent glaciers of its own." Remnants of these still remain in place and the previous existence of others is proven by ice scratches, terminal moraines and other evidence of gla- cial action found in many of our mountain valleys. The glaciers of Rainier. Adams, Hood, Jefferson, Three Sisters and Mount Mazama were much greater than now. Lindgren tells us the Eagle Creek mountains and the Elkhorn and Greenhorn mountains all had their glaciers. Russell writes of glaciers in the Stein mountains. A glacier was plowing its way over the hills .just back o