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. [Illustration: FIG. 11.--Coast of southeastern Alaska.] In reference to the broad generalization that the continental mass of North America has undergone up and down movements, greatest at the north and decreasing southward, as if moving on a hinge-line running east and west in the region of the Gulf of Mexico, it is of interest to note that the ragged coasts of Maine, Nova Scotia, Newfoundland and Labrador, due to the partial submergence of a rugged land, lie in the same latitudes as the equally ragged coast of Washington, British Columbia, and Alaska. This is more than a coincidence. The rocks on the two coasts are similar, being for the most part resistant crystalline schists, gneisses, granites, etc., and in each instance stood high above the sea for a long period during which they were deeply trenched by streams and by great glaciers, and then at about the same time, as nearly as can be judged, each region was depressed so as to allow the sea to encroach upon it. While a deeply sculptured land when partially submerged gives origin to a ragged coast, a region of similar elevation, but not cut by streams or other agencies so as to have deep valleys, when subsidence occurs produces a bold, harbourless shore without islands. The striking contrast between the deeply indented border of the continent, with its broad fringe of islands, from Mount Fairweather southward to Mount Olympus, and the remarkably uniform although bold coast-line from Mount Olympus southward to Mexico, and indeed nearly to Cape Horn, has much significance in this connection.