TO JUNCTION OF GRAND AND GEEEN KIVEKS. 35 



great basin in which we hud so long been journeying the- valley of the Mississippi 

 and entered that of the Rio Grande. At Las Vegas, too, the granite of the Rocky 

 Mountains is first seen in place, forming the axis of a subordinate anticlinal, on the 

 eastern flanks of which the Triassic and the Carboniferous formations re -appear in suc- 

 cession, thus bringing us to the base of the section which has occupied our attention 

 in the preceding pages. The exposures of these strata are much less full and satisfac- 

 tory here than nearer Santa Fe, where they are also less metamorphosed and more 

 lossiliferotis, and where the contrast and coincidences which their exposures present 

 with their eastern outcrops may be more accurately determined. 



