ENDLicH.] TOPOGRAPHY. 67 



almosfc inaccessible, but the western slope is more gentle. This hog- 

 back ridge 52 miles in length, is about 1,400 feet above the valley east 

 of it, presenting, as it does, good points for topographical and geologi- 

 cal stations. East of the valley the hills rise to considerable elevation, 

 for that section of country, so that Stations 3 and 6 are located at alti- 

 tudes, respectively, of 9,904 feet and 8,5 53 feet. Cattle Creek flows north- 

 ward through an almost straight, grassy valley into the White ', a type 

 of valley that is generally formed, of greater or less extent, wherever 

 Colorado shales are overlying Dakota sandstones. A low divide con- 

 nects this with Eifle Valley. Travelling down this latter we reach the 

 Grand. At that locality this river flows in a broad valley, hugging the 

 rising region on the south side. Low bluffs of variegated marls are 

 found north of it, forming a transition between the steep hogback ridge 

 and the valley proper. Looking off westward we see the nearly straight 

 line of the Book Cliff". Rising to a relative elevation of 3,000 feet they 

 present a bold escarpment to the south, one that is broken by passes at 

 a few places only. The regular stratification and the admirable carving 

 of fehe precipitous southern slope give this plateau-edge a characteristic 

 appearance. At many places the strata composing it have yielded to 

 eroding agents, and great masses have fallen down, producing vertical 

 walls, TLeir light color and well-defined stratification make them ap- 

 pear as successive shelves ; hence the name which has long since been 

 given to this elevated i)lateau. 



Immediately west of the hogbadk the geological formation of the 

 plateau and the latter itself commence. Ascending a gradual slope to 

 its summit, the divide between White and Grand, we obtain a view of 

 the entire structure. Forming a crest which trends about east to west, 

 the Book Cliffs retain a very constant absolute elevation of their highest 

 points, which, however, vary but slightly from the general altitude of 

 the ridge. On average, this may be stated as being 8,700 feet above 

 sea-level. An Indian trail runs along the entire length of the crest, as 

 this is by far the most convenient place for travelling. A number of 

 springs are found on either side of the divide, not far from its summit. 

 Kiding down any of the north ward- flowing streams, we observe that their 

 headwaters are generally contained in steep, narrow gulches, which cut 

 down deeply into the tertiary strata. Upon reaching a lower level, 

 however, the valleys widen, are very flat, and not unfrequently show 

 evidence of having at one time contained lakes of considerable extent. 

 These latter have disappeared in consequence of an enormous deposition 

 of diluvial and alluvial drift. Inflowing waters have carried with them 

 large quantities of sand and silt. Into the lakes where the rapid pro- 

 gress of the stream was checked, this ^'removed" material has been 

 deposited; thereby the level of the lake-beds has gradually been 

 raised and the water flowed off. We now have, instead of bodies of 

 water, an equivalent of alluvial and in part diluvial soil. Through 

 this the present streams and creeks cut deep, narrow gorges. Fre- 

 quently it is necessary to travel for some distance before a point can be 

 found where these gorges may be crossed by animals. During the rainy 

 season and early in the spring, water coming from the more elevated 

 portions of the pleateau transports large masses of the comparatively 

 light material, and renders the streams and White Eiver very muddy. 

 On either side the flat valleys are inclosed by more or less steep bluffs, 

 showing, generally, the exposed strata on their faces. Between the 

 streams the space is occupied by long, narrow, mesa-like ridges. East 

 and west these show steep slopes, are connected on the south with the 

 crest of the Book Cliffs, and northward slope very gently toward the 



