Fig. 10.—A portion of the coast of Maine.
The northern and western coasts of Alaska are mostly low, and correspond in a general way with the coastal plan of the Carolina region. The last well-marked movement of the land in that region has been in the direction of an elevation, and we find low shores, with but few harbours, similar in many ways to the coast of Texas.
It is probably true, as already stated, that the Aleutian Islands, although in part the result of recent volcanic activity, owe their peculiar and exceptional characteristics to the partial subsidence of a deeply sculptured mountain range. On the south coast of Alaska, in the region of
Mount St. Elias and Mount Fairweather, a recent and extensive elevation has occurred, which, however, did not bring the bottom of the adjacent portion of the ocean above the sea-level. This apparent anomaly seems to be due to an uprising of the rocks along the north side of a break, or belt of branching fractures, which closely approximates to the coast-line and has determined the position of the continental border in that region. The facts, so far as known, appear to show that we have here what geologists term a fault, the north or landward side of which has been raised at least 5,000 feet in very modern times, but, so far as we can judge, without disturbing the seaward border of the break. The coast between Mount Fairweather and Mount St. Elias is by far the boldest, and from a scenic point of view the most impressive, portion of the entire shore-line of North America. The mountains are young and among the highest on the continent. They rise precipitously from the margin of the sea, and are sheathed in snow and ice from base to summit throughout the year.
The margin of the continent southward from Mount Fairweather to the Columbia River, a distance in a straight line of about 1,200 miles, furnishes some of the best illustrations of the changes in coastal geography due to subsidence that our continent affords (Fig. 11). This wonderfully irregular coast is fringed with a belt of mountainous islands from 50 to 100 or more miles broad. The inlets between the bold capes and the straits separating the numerous islands are deep. The rugged, forest-clothed slopes with precipitous, and in many instances nearly vertical walls, descend into water that is frequently from 50 to over 200 fathoms deep. In brief, a deeply dissected mountain range more than 1,000 miles in length has there been depressed at least 2,000 feet below its former altitude, thus allowing the sea to flood its deep, picturesque valleys.
Puget Sound, with its numerous and frequently narrow arms (Fig. 23), is the southward extension of the partially inundated country considered above. To the west of this magnificent sound rise the Olympic Mountains, which barely escape being an island at the present stage of the
swaying of the land. On the west, as on the east border of the continent, there are drowned river-valleys, such as the Stikine, Frazer, Columbia, and Sacramento. It is not to be understood, however, that the entire Pacific coast region has been raised or depressed as a unit. There have been differential movements in some of its parts, but these are not as yet well known. In southern California, for example, raised beaches and a narrow coastal plain about Los Angeles give evidence of a modern rise of the land.