74 The American Geologist. February, i303. 
as the Canyon de Los Jemez. On the western side of this patch 
the strata dip southeast at an angle of 40*^, and on its eastern 
terminus west at a still greater angle. The rocks of this age 
exposed in the Jemez arch are limestone and shale ; Carbon- 
iferous shale appears in the lowest exposed strata. The thick- 
ness of all the strata exposed is about 700 feet. The rocks are 
upper Carboniferous as is attested by their fossils. Among 
the fossils identified by the writer and by Dr. C. L. Herrick 
are: Spirifer striatiis, Smninnla argeiitia (Athyris suhtilita), 
Productiis mcsialis, P. punctatus and P. riehrascensis, and My- 
alina siibqnadrata. 
The Permian. 
Resting conformably upon the Carboniferous strata 
are from 100 to 200 feet of reddish brown calcareous 
sandstone and shale. This area is divided into two parts by 
the granite dike which extends to the southeast through this 
region from the south tenninus of the Nacimiento mountains. 
The strata of the Permian on the one side of this dike dips 
southeast and on the other side toward the southwest, that is, 
away from the dike. That these strata are Permian is beyond 
question. Many Permian fossils were found by the writer, 
among which was Pseitdomonitis hazvni. To be sure that 
the writer was not mistaken in his decision, he submitted many 
of the fossils of these beds to Dr. C. L. Herrick with the result 
that his identification was confirmed. The strata here described 
are Permian. 
The Red Beds. — Immediately overlying the known Per- 
mian and conformable with it are blood red sandstones and 
shales fading out to white at the surface of the mesa. The rocks 
are so red that they reflect the rays of the sun, and in the morn- 
ing the reflected red light from these red mesas shines in at 
the west windows of the houses at Jemez, a mile away and 
gives every th,ing a peculiar appearance. 1600 feet of these 
Red Bed strata are exposed here. The area of the two mesas, 
previously mentioned, aggregates about thirty-seven square 
miles. Besides these two areas to the west of Jemez Pueblo 
and south of the Nacimiento mountains, a triangular area oc- 
cupies the space between the canyons Guadalupe and San Di- 
ego from Canyon de Los Jemez on the south to near the top 
of the Jemez plateau on the north. Another area occupies 
