Statements of heights and depths, of geological structures, and of topographic forms are perhaps necessary to enable one to form a mental picture of a snow-crowned mountain range which will bear some faint resemblance to the mighty original; but when one threads his way through the resinous forests on the lower slopes of the Sierra Nevada, ascends some one of the profound water-cut rifts in its side, scales the steep cliffs, traverses the crystal surfaces of the small glaciers, and finally stands on a spire-like summit covered only by the dark blue of the dome above, all thoughts of the arches and walls that support the mighty cathedral are lost in wrapt wonder and admiration of the magnificent scene about him. It is this intense feeling for the sublime and beautiful in nature that the student of geography should strive to cultivate, as well as to acquire skill in reading the prosaic history written everywhere on the mountains. This important lesson can seldom be studied to greater advantage than amid the silent awe-inspiring peaks of California. The Cascade Mountains, as previously stated, are a direct continuation, so far as the relief is concerned, of the Sierra Nevada. The geological structure of the region in northern California, where the two ranges approach each other, has been studied by J. S. Diller, of the United States Geological Survey, who concludes that they present characteristic differences. In the Cascade Mountains in northern California, Oregon, and southern Washington the rocks exposed at the surface are mainly, if not entirely, of volcanic origin, and were poured out in a molten condition as lava-flows, or as fragmental ejections from volcanoes, and in part rose through fissures and formed what are termed fissure eruptions. The rocks thus extruded are mainly composed of dark, heavy basic material, such as basalt and andesite. These outpourings of molten rocks were on a grand scale, and a large number of volcanic mountains were formed which still remain as the dominant peaks of the rugged and densely forested Cascade Range. Although the evidence now available seems to show that there is a striking difference between the Sierra Nevada and the Cascade Mountains, another significant change occurs when one follows the Cascade Mountains into northern Washington. Where the Northern Pacific Railroad crosses the range the volcanic rocks are succeeded northward by granites, schists, serpentine, etc., and Cretaceous and Tertiary sedimentary beds of much the same character as those in the Sierra Nevada.