Jcinea — Albuquerque, N. Mex. — Regan. 71 
angle to the southwest, followed by a mile of Pleistocene in 
the Salt River gap. After crossing this gap, there are three 
miles of gypsum-capped Jurassic rock, with strata dipping to- 
ward the southeast at a considerable angle, followed by Cre- 
taceous, which extends for two miles or thereabouts. The 
area here is much broken. The rocks all dip toward the south- 
east. At the south edge of the Cretaceous area the Fort Un- 
ion coal is brought to the surface by a succession of minor 
faults and a: major fault. The Fort Union is exposed for 
nearly a mile. Then the Puerco clays are to be climbed over 
for about a half-mile. On tracing the top of the divide to the 
south of the coal fields, the strata overlying the Zia mesa are 
the Zia marls. These continue in unbroken series to the Rio 
Puerco. 
Traversing the section from La Vantana to Tejon, we cross 
the following country rock : from La Vantana for a distance 
of six miles the strata are Puerco ; to the southeast of this is 
a small gypsum patch (Jurassic) probably a mile in width. 
This gypsum together with the above mentioned Puerco dips 
west at a considerable angle. Leaving the gypsum, the ex- 
posed granite core of the Nacimiento mountains, some six 
miles in width, is crossed. To the east of these mountains 
the country rock is Carboniferous, the strata of which dip at 
a steep angle toward the southeast. Crossing the Jemez river 
at Cafion, the exposed rocks for three miles are Red Beds, fol- 
lowed by Pleistocene and Eocene respectively. The Eocene 
continues to and beyond the Rio Grande for a distance of 
twenty miles ; but throughout the greater part of this distance 
it is overlaid with lava flows. From the Rio Grande east of 
south, for seven miles, the country is Pleistocene, Tertiary or 
Cretaceous, depending upon the amount of erosion. Beyond 
this point we pass over about a quarter of a mile of Carbon- 
iferous rocks; and then one mile to Tejon, over Red Beds 
'Strata which dip at an angle of 45° to the east. 
Nacimiento Mountains. — The Nacimiento mountains, the 
west extension of the Jemez group of mountains, have a core 
of red feldspathic porphyry (commonly called granite) and 
red orthoclace. The latter occupies a peripheral position and 
in one instance extends to the east of the main range for a 
short distance. A spur of eruptive granite also extends south- 
