Jcuicz — Albuquerque, N. Mex. — Regan. TJ 
The Gypsum Series. — The gypsum series consists of dark 
blood red, soft sandstones and variegated shales, covered in all 
cases where exposed, with a gypsum cap. These rocks most 
always rest upon the Red Beds, above mentioned ; but the writ- 
er was not able to determine whether they were conformable 
with the Red Beds or not. They, however, seem to be con- 
formable. 
These series only occur in patches. One large area is 
known as Mesa Blanco. Another area is just across Salt river 
opposite Mesa Blanco. Several exposures lie west of the Nac- 
imiento mountains. A very small area is exposed about six 
miles southeast of Jemez Pubelo north of the Jemez-Santa Fe 
wagon road. Other areas are exposed northeast of Tejon. 
Alesa Blanco is situated three miles southwest of the Mex- 
ican village of San Isidro south of Salt river. Its northern 
border is a fault scarp 600 feet in bight. This scarp faces Salt 
river which rests on the down faulted portion to the north of 
the fault line. Of this 600 feet the lower 550 feet are com- 
posed of characteristic dark blood red sandstones and varie- 
gated shales of the series. The upper fifty feet are gypsum. 
The northern border of Mesa Blanco is eight miles in length. 
It tapers to a point at the south. Its area is about half a town- 
ship. Its strata dip to the southeast at an angle of 40°. 
Just to the west of this mesa, and standing against it, is a 
ridge of this series wdiich extends twelve miles in a north and 
south direction. This ridge averages about a half mile in 
width, though in many places it does not exceed 100 yards, 
notwithstanding that, its altitude is most always from 300 to 
500 feet greater than that of the surrounding strata. The 
gypsum is on the western slope.. It dips west at an angle ex- 
ceeding 70°. This ridge is the southern extension of the Nac- 
imiento mountain uplift. 
The gypsum area north of Salt river and opposite Mesa 
Blanco, occupies a space of less than forty acres. It is sur- 
rounded on all sides, except the west, by Pleistocene and Ter- 
tiary deposits. The rock to the west is the Red Beds series 
from w^hich it is separated by a fault. The strata of this area' 
dip isouth and a little east at an angle of 40°. The uppermost 
exposed rock is a thirty foot gypsum stratum. This gypsum 
is of good quality ; and is used by the Mexicans and Indians 
