Page:Centennial History of Oregon 1811-1912, Volume 1.djvu/240



Dr Leidy said of one of them: "It actually bears more resemblance to the great felines, lions and tigers, than to its natural ally, the hog. ' '

There were also over a dozen species of the dog family, including the ances- tors of the wolves and foxes and that ancient line of dogs that was slowly evolv- ing into the modern bear.

There were many animals of the cat tribe with long, serrated sword-like teeth more destructive of life than the modern lion or tiger. With the great wolves the savage elotheres and the fierce flesh-tearing "saber-toothed tigers," 'tis no wonder the slow, shambling little horsesi learned to strain up on their tiptoes and run for their lives.

There was, too, a small deer no larger than a rabbit, the leptomeryx. It was allied to the musk-deer and was without antlers. This evolution of antlers in the deer is typical of the increasing struggle of life. In order to protect themselves some animals grew horns and antlers, some highly specialized teeth and claws, and some learned to increase their speed and run from their enemies.

A few of these early Miocene animals, as the rhinoceros, were much like the modem types, while the diminutive horses could barely be recognized as the pro- genitors of our modern steeds. Others, as the very common Oreodon, which must have roamed over the hills in herds, was a strange "blending of forms now so remote as the hog and the deer. ' ' The lake sediments, in which these animals of the early Miocene were buried, are called the John Day Beds. This chapter of early Miocene history was followed by one of the greatest periods of vulcanism the world has ever known.

There are two distinct types of vulcanism, the one manifested by an active volcano where clouds of smoke and steam are forced from a volcanic vent, with showers of ashes, cinders, bombs, electrical displays and great streams of molten lava pour out of the crater down the sides of the volcano. Of this tjqDC are Mount Pele and Mount Vesuvius. But the other type of vulcanism is much quieter and less spectacular. A great crack opens in the surface of the earth and from its depths wide streams of lava pour out over the land ' ' as water pours from a crack in the ice." Both types of vulcanism must have existed in Oregon during this middle Miocene age ; but geologists attribute the greater part of this wonderful outpouring of molten stone to cracks or "fissure eruptions." The valleys were filled, the hills and sometimes even the mountains were buried out of sight, and only a high plateau remained to indicate where mountain, hill and valley had been. This great outpouring of basalt covered much of eastern Oregon and Washington. A fine example of its magnitude is found in southeastern Washing- ton on Snake river at Buffalo rock, where an old mountain of schist stood at least 2,000 feet high when the lava began to flow. Of its history Russell says: "The river has cut its gorge across a buried mountain so as to expose the rocks com- posing it for about a mile on each side of the stream. The horizontal layers of basalt abut against the steep sides of the older mountain and show no evidence of disturbance at the contact. It is evident that the lower rocks have not been forced up into the basalt but that the latter was poured out in successive sheets and flowed around about a mountain of schist, and finally overtopped its summit and buried it from sight. Additional overflows of the same character were spread over the site of the buried mountain and reached a thickness of fully 1,000 to 1,500 feet above its summit before Snake river began to excavate its canyon.