Page:Centennial History of Oregon 1811-1912, Volume 1.djvu/236

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Cascade hills and Blue mountain valleys must have been very beautiful with their grand forests and many flowering shrubs; for Knowlton tells us the magnolia and cinnamon and fig trees were there, and before the close of the Eocene he adds the sycamore and sweet gum tree, the walnut, the dogwood and seven species of oak. There were sequoias to which genus the California redwood belongs, and our state flower, the Oregon grape, was then here, almost the same in species as the tall shrub, with which, we are so familiar, there were also climbing ferns and sweet mountain ferns, all flourishing in the Blue mountains or Shoshone region on the borders of a large lake that filled the John Day Valley.

During at least part of this time Payette lake covered the greater part of southern Idaho and the adjacent region of southeastern Oregon.

In the distant background of Payette lake was the majestic Wasatch range and the Owyhee mountains formed a conspicuous island in its vast expanse of waters, while on the shores grew the same rich forests that clothed the Blue mountain country.

."Western Oregon was represented during the Eocene age by a few low-lying islands in the line of the present Coast mountains, but sea shells of the period are scattered from the northern border of Siskiyou region through the valley of the Umpqua, the Willamette valley and on northward through the Puget sound country, proving that most of western Oregon was still a waste of ocean.

THE EOCENE COAL AGE

The coal-producing period in the United States east of the Mississippi river was the Carboniferous. The Rocky Mountain region looks to the Cretaceous for its supply of coal, while we of the Pacific coast are thankful for the later coal of the Eocene.

The most important field so far discovered was formed on the northern shore of our old Siskiyou region. Prof. Diller, who has made a careful study of this field, reports the land as gradually sinking during the Eocene period although with long intervals of rest. At times the field would be covered by fresh water or brackish swamps on which flourished a rank growth of vegetation destined to become a seam of glistening coal.

Then for a time the sea wOuld gain upon the land, leaving a deposit of sand and mud which later formed a layer of sandstone and shale containing Eocene shells.

Then another interval of rest and filling in of sediment would produce the broad expanse of rich swamp vegetation, which in time contributed its seam of coal. This same process repeated again and again through a long period of time gave us our Coos Bay coal. Later the old level lines of deposit became tilted and broken into endless confusion of outline.

The Tillamook and Nehalem coal was formed on an Eocene island, which like the other coal fields, experienced many quiet changes of level, sometimes covered by the life of the sea, then by the verdure of coal-producing swamps.

Prof. Diller suggests that Oregon has probably many undiscovered coal de- posits hidden away in our coast mountains and on the western side of the Cas- cades, covered now perhaps by a dense growth of forest trees.

The Eocene indicated on the map is found in the southwestern part of the