248 ANNUAL KECORD OF SCIENCE AND INDUSTRY. 



west and southwest for about 15 miles, when it again turns, 

 and flows generally northwest until it joins the Dolores. 

 Between the San Miguel and Lone Cone, the sandstones of 

 the Dakota group (or 'No. 1 cretaceous) are nearly horizontal, 

 forming a plateau which, on approaching the mountains, has 

 a capping of cretaceous shales. 



Bevond the bend, the San Migjuel flows in a monoclinal 

 valley, in which the canon walls are of the same description 

 as in the upper part of its course. As the mouth is ap- 

 proached the red beds appear. Between this portion of the 

 course of the San Miguel and the almost parallel course of 

 the Dolores, which is in a similar monoclinal rift, there are 

 tw^o anticlinal and two synclinal valleys parallel to each 

 other. They are all occupied by branches of the Dolores. 

 Lower Cretaceous, Jurassic, and Triassic strata outcrop, and 

 present some interesting geological details, which will be 

 fully considered in the report on the district. The Dolores 

 River comes from a high plateau in a zigzag course, flowing 

 sometimes with the strike and sometimes with the dip of 

 the strata. Its general course on the western line is about 

 northwest, from which it turns to the northward and west- 

 ward, finally changing to northwest again to its junction 

 with the Grand. It is in caiion the greater part of its 

 course. In the region of country north of Grand lliver the 

 geological formations extend uninterrujjtedly from the red 

 beds exposed on Grand River to the white tertiary cliffs 

 forming the summit of the "Roan Mountains," or Book Cliffs. 

 The Grand is generally in a caiion in the red beds. 



On the north side the No. 1 cretaceous sandstone forms 

 a hog-back sloping toward the cliff's. Between the crest 

 of this hog -back and the cliffs there is a broad valley 

 formed by the erosion of the soft cretaceous shales which ex- 

 tend to the base of the cliff's, and in some places form their 

 lower portion. The cliff's are composed mainly of cretaceous 

 beds, rising one above another in steps, until an elevation of 

 about 8000 feet is reached. The summit is the edge of a 

 plateau sloping K.N.E. This plateau is cut by the drainage 

 flowing into the White River from the south. These streams 

 rarely cut through the tertiary series. 



Coal of poor quality is found in the sandstones of the 

 Dakota group, and also in the sandstones above the middle 



