SHUMARD—GEOLOGY OF N. MEXICo. 287 
e being composed of fine-textured 
gray granite. At the point of eat the valley is abou 
and has a smooth, even ce, COV- 
ered, for the most part, with short grass; but, after en 
it, we pass coarse, reddish s: detritus of eruptive 
Bl. ~After donvell for twenty-eight 
miles, over these deposits of sand sak etcteels, wieteaced tip 
ssl y gral dence ints te valoy ofthe Ta 
ene by ag it into the valley of the I 
ie, G * : : L -¢ - of 
smooth valley, from a fourth to a half a mile ‘wi 
terminate mm “The Ps 
