Page:The Pacific Monthly volumes 1-3.djvu/28

 is done it is impossible to study the subject in detail.

The glacial epoch is well marked in the Northwest, and all the northern canyons of the great peaks as far south as Mount Shasta still contain glaciers, many of them exceeding the celebrated glaciers of the Alps.

The glaciers become larger and reach further down the mountain sides as you go north, until Alaska is reached, where all the mountain summits are capped with wide fields of snow, and the glaciers force their way down to the sea, and every gorge is filled. During the glacial age vast fields of ice and snow covered the Northern hemisphere of both continents for a great distance from the poles to an unknown depth, driving all existing forms of animal life towards the sub-tropical zone and substituting arctic forms.

The evidence of erosive action of glaciers is unmistakable in many localities, and one of the finest effects of such action may be seen near the city of Victoria, Vancouver island. Opposite the city, across the bridge, on the reservation, is a large area of bare basaltic rock ploughed and furrowed by glacial action, the striae running from northwest to southeast. At the time the ocean wharf was building, the rock was uncovered during the process of grading a road, and the glacial markings were bright, clean and not weathered. Long grooves, generally parallel and often 10 or 12 inches deep, gouged out of the solid ledge, looked like the handiwork of a skilled stone-mason and were polished as smooth as a piece of statuary. Science is also unable to inform us of the momentous changes that must have taken place to produce the ice age, when all plant life over a large part of the Northern hemisphere was destroyed and animal life of the temperate clime driven towards subtropical regions. Some theorists have advanced the hypothesis that the surface of the sun was to a very large extent covered with spots which are now seen to prevail at successive intervals of 11% years, and that owing to this prevalence the amount of heat and light given forth was very much lessened. This aspect of the sun being continued through many thousand years, polar conditions of climate were practically maintained over a large area of the Northern hemisphere. Gradually the ice and snow disappeared from the temperate zones, the glaciers retreated to their proper homes in the North, and life once more flourished over a smiling land.

The northwest coast, in common with all parts of the globe, has been subject to great and frequent oscillations of level, epochs of subsidence and upheaval being well marked in the Tertiary and post-Tertiary or latest geological age. These oscillations sunk the land below the surface of the ocean many thousand feet, raising it again to present elevations, as is shown by the abundance of fossil marine life on the summits of very high mountains. I have gathered shells of clams, identical with existing species, on the summit of Bald mountain, near Port Orford, 3,000 feet above the sea level. While engaged in professional duties near San Simeon, on the California coast, I discovered a bed of the "Ostrea Titan," or gigantic fossil oyster, specimens of which were two feet or more in length, with a thickness of shell near the hinges of four or five inches. A half dozen raw or on the half-shell would be a formidable dish to set before a king. Above this oyster bed was a ledge of coral rock, and there on the mountain side, among the sagebrush, blooming ceanothus and wild morning-glory, firmly cemented to the extreme point of a projecting coral rock, was the beautiful, enameled tooth of a shark. But how changed the scene; instead of some dark, unfathomed cave far beneath the blue waters, where the sea anemone opened its petals among the corals, where the fierce and predatory shark pursued its prey, the jay flew screaming down the canyon, and the wild bee hung to the nodding flowers.

The oscillations of level of the land can be studied very conveniently and near at home on the adjacent coast. There exists a long line of high cliffs between Siletz bay and the mouth of Salmon river, where the erosive action of the surf has exposed to view a great section of alternate beds of sand, gravel and marl or bog mud, in which are imbedded the roots and prostrate trunks of spruce and alder trees, of the same varieties as existing species. These trunks protrude from the banks, greatly compressed by the immense