90 SURVEY OF COLORADO AND NEW MEXICO. 



"beds of lignite, or impure coal, or carbonaceous clay, are found in groups 

 of strata which should be classed as middle tertiary -, but these do not 

 seem in any case to be of any economical importance. 



ISTear Hard Scrabble Creek, a small branch running into the Arkansas 

 Eiver just below Canon City, there is a small area, about eight miles 

 square, occupied by coal strata, for which I propose the pro\isional 

 name of Cation City group. I have but little doubt that careful study 

 will show that it is a fragment of the great lignite group of the North. 

 The next group comprises the coal beds of the Eaton Hills, which 

 I suspect is also a portion of the great lignite group, and will event- 

 ually be found to be synchronous with it. I have called it the Eaton 

 Hills group. 



The next group of coal strata occurs in Placer Mountains, New Mex- 

 ico, about thirty miles south of Santa Fe. The lithological character of 

 the beds or rocks are very similar to those of the lignite group further 

 north, but the evidence in regard to their age, or i)arallelism with the 

 lignite group, is not so clear. While I regard the true coal beds of the 

 West as lower tertiary, yet these Placer Mountain beds present the 

 appearance of greater antiquity than the coal beds further north. Still, 

 the numerous varieties of deciduous leaves which I have obtained from 

 rocks just overlying the coal beds indicate that they are lower tertiary ; 

 and with this belief I have named them the Placer Mountain group. 



Overlying the Placer Mountain beds, in the valley of Gallisteo Creek, 

 is a vast thickness of exceedingly variegated sands, sandstones, and 

 calcareous sandstones, characterized mostly by containing an abundance 

 of silicified wood; but no other fossils have, as yet, been discovered. 

 I have given this series of beds the name of Gallisteo sands, and they 

 are doubtless middle tertiary. 



In the valley of the Eio Grande, at least from Albuquerque to the 

 north end of San Luis Yalley, a series of marly sands of a -light color 

 prevail to a greater or less extent. They exhibit their greatest thick- 

 ness north of Santa Fe. To this group I have given the name of Santa 

 Fe marls; and they are doubtless of the age of upper tertiary, and 

 synchronous with the upper beds of the White Eiver group as seen 

 along the North and South Forks of the Platte and near Cheyenne. 



In the valley of the Arkansas, north of the Poncha Pass, is a line 

 development of the light-colored marls, doubtless of the same age with 

 the Santa Fe marls, which I have designated by the name of the 

 Arkansas marls. I have as yet obtained no well-defined fossils from 

 either the Santa Fe or Arkansas marls ; yet bones of some large ani- 

 mal, probably mastodon or elephant, have been found in them. I have 

 no doubt that more careful explorations will show that a fauna and 

 flora of greater or less extent will characterize all these grou])s. 



Along the Union Pacific railroad we find in the Laramie Plains a most 

 extensive exhibition of the great lignite grouj). The first coal beds of 

 great economical value occur near Carbon and at Separation. From 

 Creston to Bitter Creek there are a series of purely fresh-water beds, 

 with some beds of impure lignite, with vast quantities of fossils be- 

 longing to the genera Unio, Afelania, Yivipara, Selix, &c. This group I 

 regard as middle tertiary, and the strata are very nearly horizontal. I 

 have regarded these beds as separated from the lower tertiary or true 

 lignite group, and have designated them by the name of the Wash^kee 

 g TjQ up- A little east of Eock Sj^ring station a new group commences, 

 composed of thinly laminated chalky shales, which I have called the 

 Green Eiver shales, because they are best displayed along Green Eiver. 

 They are evidently of purely fresh- water origin, and of middle tertiary 



