gahsbtt.] GEOGRAPHY GEAND RIVER. 423 



west as the eye can reach. The cliffs on the south edge of this plateau 

 are perpendicular, and even in places overhanging, and the tops pro- 

 jecting, so that, at noon in August, they cast a shadow on the vertical 

 wall beneath. 



Below the Plateau range, the valley widens immensely. This valley 

 is not more inviting than the one above the North Mam plateau. 



In latitude 39° .08', longitude 108° .19' the Grand is crossed by the crest 

 of a range of hog-backs. This crest has a general direction slightly west 

 of north and east of south. The dip is toward the east, and is slight, 

 and as the Grand does not cross this range in a direction contrary to 

 that of the dip, but obliquely to it, the caiion which it cuts is very long, 

 being about 15 miles. It increases in depth very gradually, until, 

 at the lower end, it is about 1,800 feet. The western edge of this line of 

 hog-backs is nearly vertical, and the exit of the river from the canon is 

 very abrupt. The surface of this hog-back is very much broken and cut 

 by side-canons. 



Plateau Creek heads in the eastern part of the plateau, and about mid- 

 way between the Grand and Gunnison Rivers. It flows fir.st northwest, 

 down the slope of the plateau, cutting deeper and deeper. At station 49 

 its course changes to west, and it holds this course very constantly to its 

 mouth, in the middle of the Hog-back Canon. This plateau has an 

 enormous amount of drainage. Near its top the valleys are broad, flat, 

 and marshy, with numerous small lakes or ponds. The best land in the 

 district for agricultural and stock purposes, is that on and near the tops 

 of the high mesas ; but the great elevation precludes their use for these 

 purposes. 



Plateau Creek drains the whole of the northern slopes of the main 

 plateau and the southern slopes of the North Mam plateau. All the 

 streams flowing to it from the main plateau have a course nearly due 

 north, forming a very regular system of drainage. The valley of this 

 stream is, throughout the greater part of its course, quite wide, with, in 

 places, enormous extents of bench-land between its branches. 



At the foot of Hog-back Caiion the Grand emerges into a broad valley 

 in which it meets the Gunnison. This valley is of enormous extent, 

 stretching far dowu the Grand, even beyond the Sierra la Sal and up 

 the Gunnison ten miles above the mouth of the Uncompahgre River, 

 and up the Uncompahgre for at least forty miles. Its width, on the 

 Grand, below the mouth of the Gunnison, is about ten miles. It is 

 bordered on the northeast, for some distance, by the range of hog-backs 

 mentioned above; on the southwest, by a plateau lower than that 

 described above and of a different character. The Grand hugs closely 

 the edge of this plateau. The river-bottom of the Grand is upward of a 

 mile in width, well timbered with cottonwoods, and very fertile. The 

 rest of the valley is bench-land, elevated about 100 feet above the river, 

 at the edge, rising very gradually toward the range of hog-backs. The 

 soil is gravelly, with much alkali, and produces only greasewood and 

 sage. 



The part of this valley included between the Grand, the Gunnison, 

 and the west edge of the great plateau is nearly triangular in shape, 

 the two rivers and the edge of the plateau forming the sides. It also 

 extends up the Gunnison, east of the western edge of the plateau, to 

 longitude 107° 55'. The area of this part of the valley is three hundred 

 square miles. 



The western edge of the great plateau consists of a precipice of basalt, 

 averaging 200 feet in height, below which there are timbered ridges 



