Perhaps no portion of the earth's surface is more irremediably sterile, none more hopelessly lost to human occupation, and yet, an eminent geologist has said, it is the wreck of a region once rich and beautiful, changed and impoverished by the deepening of its draining streams--the most striking and suggestive example of over-drainage of which we have any knowledge. Though valueless to the agriculturist, dreaded and shunned by the emigrant, the miner and the trapper, the Colorado plateau is a paradise to the geologist, for nowhere else are the secrets of the earth's structure so fully revealed as here. Winding through it is the profound chasm within which the river flows from three thousand to six thousand feet below the general level for five hundred miles in unimaginable solitude and gloom, and the perpendicular crags and precipices which imprison the stream exhibit with, unusual clearness the zoological and physical history of the land. [Illustration: SWALLOW CAVE, GREEN RIVER.] [Illustration: INDIANS NEAR FLAMING GORGE (SAI-AR AND FAMILY).] It was this chasm, with its cliffs of unparalleled magnitude and its turbulent waters, that Major Powell explored, and no chapter of Western adventure is more interesting than his experiences. His starting-point was Green River City, Wyoming Territory, which is now reached from the East by the Union Pacific Railway. On the second morning out from Omaha the passengers find themselves whirling through sandy yellowish gullies, and, having completed their toilettes amid the flying dust, they emerge at about eight o'clock in a basin of gigantic and abnormal forms, upon which lie bands of dull gold, pink, orange and vermilion. In some instances the massive sandstones have curious architectural resemblances, as if they had been designed and scaled on a draughting-board, but they have been so oddly worked upon by the elements, by the attrition of their own disintegrated particles and the intangible carving of water, that while one block stands out as a castle embattled on a lofty precipice, another looms up in the quivering air with a quaint likeness to something neither human nor divine. This is where the Overland traveller makes his first acquaintance with those erosions which are a characterizing element of Western scenery. A broad stream flows easily through the valley, and acquires a vivid emerald hue from the shales in its bed, whence its name is derived. Under one of the highest buttes a small town of newish wooden buildings is scattered, and this is ambitiously designated Green River City, which, if for nothing else, is memorable to the tourist for the excellence of the breakfast which the tavern-keeper serves. [Illustration: INDIAN LODGE NEAR FLAMING GORGE.]