80 The American Geologist. February, 1902. 
NOTES OF A GEOLOGICAL RECONNOISSANCE IN 
EASTERN VALENCIA COUNTY,* NEW MEXICO. 
By D. WILSON JOHNSON. 
PLATES II AND III. 
Southeast of Albuquerque, New Mexico, and east of the 
Manzano mountains, lies a region of low plains bounded on the 
west by the wooded foothills of the Manzanos, and on the east 
by a low and barren ridge terminating at the north in the hills 
of Pedernal and at the south in the Animas hills. The abrupt 
exposure of the Jumanez mesa bounds this broad valley on the 
south, while to the north the plains continue almost unbroken 
to the San Pedro and Ortiz mountains, and the rough country 
east of these groups. The whole southern portion of this val- 
ley is comprised in what is known as the “Antonio Sandoval 
Grant,’ and is especially noted for the salt and alkali basins 
which occupy its central portion. 
The low ridge referred to as marking the eastern limit of 
the southern portion of this valley is not a well defined boun- 
dary line, but merely a gentle rise above the general level of 
the valley, east of which the plains stretch unbroken by any 
prominent landmark to the horizon. In two localities on these 
plains east of the dividing ridge are found basins more or less 
alkaline and saline: the first near the Mexican village of Pinos 
Wells, southeast of the Animas hills some twelve or fifteen 
miles; the second northeast of the village about fifteen 
miles. During the summer of 1900 these different basins 
were visited by the writer, in company with Harry N. Herrick, 
in the interest of the University Geological Survey. 
The geological conditions are extremely simple. There is 
a constant dip to the east, or possibly a little south of east, 
quite marked along the western border of the valley, but becom- 
ing less noticeable as one passes further east and away from 
the axis of the Carboniferous uplift which produced the Sandia, 
Manzano and more southern ranges, until it is almost if not 
quite imperceptible at the exposures about the most eastern of 
the saline basins. A few miles northwest of Berrendo springs 
there are several imperfect exposures of alternating lime and 
 *Bor the “Report of a Geological Reeonnoissance in Seater Socorro and 
and Valencia counties,’’ C. L. HERRICK, see vol. xxv, No. 6 of the AMERICAN 
GEOLOGIsT. 
7 
