GEOLOGICAL SURVEY OF THE TERRITOEIES. 329 



My researclies at and around Golden have been rewarded by the dis- 

 covery of the finest and best preserved specimens of fossil-leaves that have 

 ever been found in this country, with the exception, perhaps, of those of 

 Black Butte. They were obtained, 1st. From the hard white sandstone 

 under and interlying the beds of coal, the white sandstone hardened 

 by metamorphism as described above; 2d. From beds of white clay 

 upheaved against the sides of the basaltic dike, a clay hard as silex from 

 metamorphism, having mostly remains of palm-leaves ; 3d. From three 

 miles south of Golden, from a sandstone still upheaved near the tail of 

 the dike, but scarcely changed by heat and easily cut in large pieces. 

 These specimens should indicate a different degree of hardening by heat, 

 according to distance from the granitic mountains on one side, and from 

 the basaltic dike on the other. It is remarkable, however, that the lignite 

 obtained from the mines at Golden, like this plant-bearing sandstone, 

 scarcely bears any trace of the action of heat. 



In following the narrow valley from Golden to Marphy's coal-beds, 

 tbe same strata worked at both places have been traced all along in a dis- 

 tance of more than five miles. From Murphy's or Ealston Creek, the 

 Lignitic is covered by debris^ under which evidently the same formation 

 is hidden, with the same kind of strata. For the lignite is worked 

 at Leiden's, about two miles north of Murphy's, from same nearly 

 vertical strata; and five miles farther north, the formation cut by Coal 

 Creek exposes still the same Lignitic measures, now tending to their 

 natural horizontal position by the disappearance of the basaltic dike. 

 StiU farther north, in the valley of Boulder Creek, at Marshall's, 

 Wilson's, Brigg's, Erie, &c., the Lignitic exposes, by the number and 

 thickness of its veins of coal and of its beds of sandstone, a fullness of 

 development remarkable indeed, and scarcely seen elsewhere. From 

 Golden to Marshall's I have not obtained any specimens of fossil-plants. 

 A careful examination of the numerous beds of sandstone exposed there 

 would have demanded much more time than I had at my disposal. At 

 Marshall's, besides specimens of interesting dicotyledonous leaves, I 

 found few fucoidal remains, the lower sandstone being there below the 

 level of the country. The main coal, by the abundance of large trunks 

 of half-carbonized, half-petrified wood, shows a character v/hich is re- 

 marked, too, at the main coal of the Arkansas Eiver on the land of the 

 Colorado Improvement Company. At Erie, the Lignitic is worked as 

 at Marshall's, near the level of thecountry, and therefore no sandstone 

 is exposed. In the shaly, sandy clay overlying the coal, I found only 

 remains of dicotyledonous leaves and palms. 



The continuity of the Lignitic formation is still traced farther north 

 by Dr. Hayden, who, in his report of 1869, indicates a bed of coal opened 

 and wrought to some extent, twenty miles south of Cheyenne. The 

 section of the locality, as given on page 17, positively marks the position 

 of this Lignitic as above a massive sandstone 50 feet thick overlying 

 Cretaceous Xo. 5 ; and the same section, too, identifies some of the 

 strata with those of Marshall's and of Black Butte by beds or aggrega- 

 tions of oyster-shells, Ostrea subtrigonalisf curiously represented by 

 homologous or identical species at about the same horizon at these 

 named localities. I believe that farther north, to Cheyenne, the same 

 formations are still present, only hidden by the mass of detritus brought 

 over them from the mountains. 



Around Cheyenne the predominant formation is a thick bed or a suc- 

 cession of beds of conglomerate sandstone of the same composition and 

 in the same position as the conglomerate of Gehrung's or of Monument 

 Park in Colorado. It here overlies, as at Gehrung's, thick beds of black 



