io6 Bulletin of Laboratories of Denison University [Voi. xi- 
south, first, South Mountain with its westward extension 
of granite hills, which we may call the San Antonito mountains. 
Next north is the San Pedro peak with its foot hills. Then the 
Ortiz group and, finally, north of the Galisteo creek, the Cer- 
rillos range. In all these, except the San Pedro mountain, the 
greater part of the uplift seems to be of granite of the meta- 
morphic series. The Carboniferous limestone skirts the south- 
ern border of South Mountain and extends nearly to San An- 
tonito and encloses the area of Cretaceous and Jura Trias ex- 
tending from Tijeras to the latter place. Directly west of South 
mountain there is preserved a bold escarpment of the Carbon- 
iferous. Here the granite is exposed from time to time below 
the Carboniferous but the lower 175 to 185 feet is partly cov- 
ered and partly obscured by an interpolated intrusive. (A 
section of this rock shows it to be an orthoclase porphyry 
with hornblende and diallage ?) The upper part of this 
portion seems to be an earthly limestone. This is followed 
by ten feet of fine shale such is commonly found within 
a hundred feet of the quartzite, and this is followed by a 
fossiliferous shale with the characteristic faces of the lower 
member of the series. Productus Spirifer opima and Mar- 
tinia are abundant. Seventy-five feet of dark bedded lime 
follow, after which the lime has a vescicular character with 
nodules of chert for one hundred and ten feet. The next 120 
feet is more homogeneous and of a gray color and has a large 
species of Athyris as the characteristic fossil. The upper twenty 
feet of this member inclines to be shaly with a yellow color and 
is filled with bryozoa. At this level too is a belt of Fusulina 
limestone. The remaining forty-five feet is made up of massive 
dark gray lime with bryozoa. It is evident that this section 
lacks the upper portion and the sandy beds noticed in sections 
further south and west are here absent. 
From this exposure to a point west of the Ortiz mountains 
the limestone is the country rock, though it nowhere rises to 
so high a level as here. It apparently extends uninterruptedly 
between South Mountain and San Pedro Mountain and not far 
east of the town of San Pedro it is sufficiently charged with 
