SHUMARD—GEOL. OF N. MEXICO. 851 
fable 
hills the lava stream was observed gradu aly dastehadins aiid 
branching, it being in a number of ees = through by the 
Rio Grande, which wi winds a tortuous course over vol- 
canic rocks, and affords, by its smooth skiing surface and 
grassy borders, a vetoed ——— to the otherwise barren and 
Ponty character of the scenery. 
ite in the day, we ahivea at the “Fra Cristoval Moun- 
tain? it is about eighteen miles in length, and rises abruptly 
_ tothe height of fifteen hundred or two thousand feet. Its 
os ening is pretty generally north and a and_ its 
is partly washed by the waters of the Rio 
posing this mountain are principally massive 
hard bie and gray suberys talline cae tee of the 
“vuerous group. In places, the beds are largely com- 
| of the remains of Cris sirnpsral ged triegiel ona, green-_ 
fibrous gypsum are seen traversing them in various 
in W. noe ie 
aed at oe of t 
» Grande, The 
