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Show • • CHAPTER XI. ON THE PBYSIOAL FEATURES OF Tng VALIJEY OF THE OOLORADO. The topographic features of tho valley of the Colorado, or the area drained by the Colorado River and its tributaries, are, in many respects, unique,'as some of the e features, perhaps, are not reproduced, except to a very limited extent, on any other portion of the surface of the globe. Mountains, hills, plateaus, plains, and valleys are hero found, as elsewhere throughout the earth; but, in addition to these topographic elements in the scenic features of the region, we find buttes, outlying musses of stratified rocks, often of great altitude, not as dome shaped or conical mounds, but usually having angular outlines; their sides are vertical walls, ten·aced or buttressed, and broken by deep, re-entering angles, and often naked of soil and vegetntion. ' rrhen we find Jines of cliffs, abrupt escarpments of rock, of grea.t length and great height, revealing the cut edges of strata swept away from the lower side. Thirdly, we find canons, narrow gorges, scores or hundreds of miles in length, and hundreds or thousands of feet in depth, with walls of precipitous rocks. In tho arid region of the western portion of the Unite~l States, there aro certain tracts of country which have received the name of mauvaises terres, or bad-lands. "rhese arc dreary wastes-naked hills, with rounded or conical forms, composed of sand, sandy clays, or fino fragments of shaly rocks, with stoep slopes, and, yielding to tho pressure of the foot, they are climbed only by the greatest toil, and it is a labor of no inconsiderable magnitude to penetrate or cross such a di trict of cou ntry. The stoop hills are crowded together, and the water-ways separating them arc deep ar1·oyas. \Vhere the mud rocks or sandy clayR and shales, of which the hills are eomposed: are intorstratified with occat~ional harder bed ·, the slopes nrc terra,ced; and when these thinly bedded, though hardei·, rockii prevn.il, tlw |