This view of Mr. Becker is amply sustained by many other obvious facts, some of which may be easily observed by tourists who visit the Yosemite Park. The freedom of the abutting walls of this cañon from talus, as well as the freshness of the glacial scratches upon both the walls and the floor of the tributary cañons, all indicate a lapse of centuries only, rather than of thousands of years, since their occupation by glacial ice. The freshness of the high-level terraces surrounding the valleys of Great Salt Lake, in Utah, and of Pyramid and North Carson Lakes, in Nevada, and the small amount of erosion which has taken place since the formation of these terraces, point in the same direction--namely, to a very recent date for the glaciation of the Pacific coast. We have already detailed the facts concerning the formation of these terraces and the evidence of their probable connection with the Glacial period. It is sufficient, therefore, here to add that, according to Mr. Russell and Mr. Gilbert (two of the most eminent members of the United States Geological Survey, who have each published monographs minutely embodying the results of their extensive observations in this region), the erosion of present streams in the beds which were deposited during the enlargement of the lakes is very slight, and the modification of the shores since the formation of the high terraces has been insignificant. According to Mr. Gilbert: "The Bonneville shores are almost unmodified. Intersecting streams, it is true, have scored them and interrupted their continuity for brief spaces; but the beating of the rain has hardly left a trace. The sea-cliffs still stand as they first stood, except that frost has wrought upon their faces so as to crumble away a portion and make a low talus at the base. The embankments and beaches and bars are almost as perfect as though the lake had left them yesterday, and many of them rival in the symmetry and perfection of their contours the most elaborate work of the engineer. There are places where boulders of quartzite or other enduring rock still retain the smooth, glistening surfaces which the waves scoured upon them by clashing against them the sands of the beach. "When this preservation is compared with that of the lowest Tertiary rocks of the region--the Pliocene beds to which King has given the name Humboldt--the difference is most impressive. The Pliocene shore-lines have disappeared.