270 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



carboniferous in the north and extending up into the ter- 

 tiary at the south. The strike is east and west, the dip 

 south from 5 to 45. Working to the westward, Mr. Holmes 

 found the whole series flattening out, i. e., approaching a 

 horizontal position. At the same time a gentle rise toward 

 the northwest brings the cretaceous rocks to the surface, or, 

 at least up to the general level of the country. The lignitic 

 group is, therefore, confined to the southeast. From Station 

 1 an outcrop of the light-colored sandstones, belonging to the 

 base of this series, could be traced along its entire course 

 through his district. 



The heaviest seam of coal examined in these beds is twen- 

 ty-six feet in thickness. It is rather light and impure on the 

 surface, but probably of moderately good quality. A num- 

 ber of less important seams could also be recognized. 



West of the Rio La Plata the upper cretaceous beds are 

 raised to a higher plain by a slight monoclinal fold, after 

 which they spread out to the west, forming the Mesa Verde. 

 This plateau extends nearly to the San Juan on the south, 

 west beyond the Rio Mancos, and north to the middle of the 

 district, an area of more than seven hundred square miles. 

 On these three sides the Mesa breaks abruptly off in lines of 

 irregular escarped cliffs, generally from one thousand to two 

 thousand feet in height. 



The striking features of this series are the exposure of 

 two horizons of massive sandstones. The upper forms the 

 top of the Mesa, the lower, one thousand feet below, pro- 

 duces a subordinate shelf. Shales intervene between the 

 sandstones of the lignitic and the upper sandstones of the 

 Musa, and between these and the lower sandstones. Around 

 the base of the Mesa the lower cretaceous shales outcrop. 

 The belt covered by these is narrow, and is followed by the 

 hard sandstones of the Dakota group, which is very persist- 

 ent here as elsewhere, and occupies the higher level of the 

 entire Mesa country to the west and north. The Jurassic 

 strata and the "Red Beds" are exposed in the sides and 

 bottoms of the numerous canons and stream courses, the lat- 

 ter only in the greater valleys, and in patches about the 

 bases of the trachytic areas. The Jurassic section is, in the 

 upper part, almost identical with the corresponding series 

 in other parts of Colorado, but at the base has a larger de- 



