TO JUNCTION OF GRAND AND GREEN RIVERS. 67 



Knife. By both these axes the sedimentary rocks arc much disturbed and metamor- 

 phosed. 



On the north side of the river at Abiquiu, just beyond the ancient ruins whioh 

 crown the bluff, is a little valley cut from soft white and blue conglomerate, Band- 

 stones, and tufas, which, though destitute of fossils, I have suspected to be of Tertiary 

 age. This deposit is entirely local, and seems to have idled .a basin or valley, as the 

 fresh-water Tertiaries of the interior of the continent so frequently do. The strata 

 have a thickness of perhaps 150 feet, and have been worn by erosion into most strik- 

 ing imitations of spires, churches, pyramids, monumental columns, and castles. At 

 Jemez, a few miles south of Abiquiu, the picturesque buttes, which stand isolated in 



the open valley, are composed of precisely similar materials. These latter are 

 evidently remnants of a mass which once tilled the valley about them, nearly all of 

 which has been removed by erosion. They are to be classed with the other patches 

 of fresh-water Tertiary in the vicinity of Santa EM; local deposits made after all the 

 great topographical features of the surrounding country had received nearly their 

 present forms. As the most perfect parallelism seems to exist between the castellated 

 buttes of Abiquiu and Jemez, I am disposed to refer them to the same epoch. 



Above Abiquiu the Chama flows through a country quite different from that which 

 I have described. West of the Yalles, the Nacinriento Mountain terminates abruptly, 

 leaving a large area of open country between it and the mountains which may be 

 supposed to be its representative on the north. This area, topographically and geo- 

 logically, is but a portion of the great Colorado plateau ; there being nothing but a, 

 low line of elevation — the prolongation of the Xacimiento axis, by which the strata 

 are not often broken through — to separate it from the table-lands bordering Canon 

 Largo and the Upper San Juan. After leaving the mountains in which it takes its 

 rise, the valley of the Chama is, therefore, as far as Abiquiu, a valley of erosion, and 

 is bordered on either side by the cut edges of the different steps of the plateau. Im- 

 mediately above Abiquiu, the sides of the valley are composed of the Triassic forma- 

 tion. A few miles further west, the Lower Cretaceous sandstones cap the table-lands 

 and floor a plain, the precise counterpart, except in extent, of the great sage-plain west 

 of tlu' Sierra de la Plata. At the Yada del Chama, still higher up the stream, wereach 

 the base of a wall, more than a thousand feet in height, composed of the Middle and 

 Upper Cretaceous strata, corresponding, and perhaps connecting, with the table-land 

 bordering ('anon Largo, of which a full description will be given hereafter. 



ABIQUIU COPPER .AH MIS. 



In a former chapter I have referred to the deposits of copper found in the sedi- 

 mentary strata in various portions of New Mexico, and have enumerated several locali- 

 ties — San Miguel, Jemez, &C. — where this copper exists in considerable abundance, 

 and where mines were formerly extensively worked to obtain it. r J ne old mines of 

 Abiquiu belong to this category. To the residents of the vicinity they are objects of 

 much interest and some wonder, and having had our curiosity excited by their glow- 

 ing accounts of them, while our party was at Abiquiu we paid them a visit, under the 

 guidance of Mr. Albert II. Pfeiffer, resident Indian agent, whoso intimate knowledge 



