Page:Oregon Historical Quarterly volume 13.djvu/16

8 the present Polk County Hills reaching from near Salem northwest to Amity. Then there was the island of the Waldo Hills and Knox's, Ward's and Peterson's Buttes of Linn County, while far to the south there were small low lying islands, the buttes of Lane County, and old Spencer towering above them all in his solemn dignity.

We have seen that Oregon still had many glaciers, that were remnants of the age of ice. Glaciers, as you know, are only slowly moving and solidly frozen rivers. But the waters of a river pass swiftly on leaving the larger stones found in their pathway, while a glacier slowly reaches out or down and freezes to the loose stones as it passes on, making them a part of its own frozen mass. When in the progress of its journey it reaches warmer waters, a great mass of ice often splits off from the front of the glaciers and the iceberg sails away like a phantom ship, carrying the frozen load of rocks which it has gathered in the heart of the far distant mountains. It was so on the Willamette Sound. We have no native granite in the valley, but throughout its entire length from near Portland and Forest Grove to near Eugene, granite boulders, varying from hand specimens to the weight of several tons, were dropped into the Willamette Sound by melting icebergs. An eminent authority assures us that very large boulders found in Yamhill County are of British-American type of granite. And these must have been carried through Puget Sound across the Columbia Valley and into Willamette Sound from some point beyond our northern boundary.

For ages before the ice period many varieties of the horse and camel had made their home in Oregon. But as the climate became colder a part of these evidently migrated to South America, while it is thought many may have died of some