74 
GEOLOGICAL REPORT-THIRTY-FIFTH PARALLEL. 
the position of the strata is found in the notes under date of August 22, when they were 
observed to he horizontal or nearly so. This was between Camps No. 21 and No. 22. The 
next day, beyond Camp 22, the strata were observed to dip southwest at an angle of from five 
to ten degrees. At Camp 28 the strata were inclined at an angle of ten degrees towards the 
south, tl e trend being east, and west. Beyond Camp 28 the strata were horizontal. Tin's was 
in the vicinity of Roc k Mary and other natural mounds formed by the denudation of horizontal 
strata. The great beds of gypsum at and near Camp 30 were horizontal ; but near Camp 31 a 
bed of gypsum dipped towards the north at an angle of ten degrees. From this place to the 
vicinity of Canon Blanco (Camp 54) the strata appear to be horizontal; but in the canon they, 
together with the upper strata—the Jurassic, according to Mr. Marcou—are inclined towards 
the southeast, and the heads of the beds are turned towards the mountains. Beyond this, and 
on the next day, a line of hills was passed, in which the strata were uplifted and dipped each 
way under various angles, from fifteen to sixty degrees. The disturbance was so great that 
portions of the upper strata, the yellow sandstone, had slid upon the marls of the formation, 
and in some places were overturned. (October 1.) The explorations of the next day developed 
the existence of dykes of trap, one being found ten feet wide, cutting the strata in a direction 
“ 30° E E N. to 30° W.W.S.” Beyond this the beds of the “Trias’’ are said to be upheaved, 
and generall}' inclined to the south-southeast, under angles of ten or fifteen degrees. A short 
distance beyond Camp 57, on the Santa Fe river, Mr. Marcou saw, in the north, elevated hori¬ 
zontal beds of “ New Red,” capped with a layer of basaltic lava. This locality is almost south 
of Santa Fe, and beyond the Santa Fe mountains. At San Antonio, on the eastern side of the 
Sandia or Albuquerque mountains, the strata dipped towards the east, the angle of inclination 
varying from twenty to forty-five degrees. A few miles northeast of this place trap dykes were 
found traversing the “ Trias” in several directions, as has been already described. 
In the valley between the Sierra Madre and the Santa Fe and Albuquerque mountains, a 
short distance beyond the Puerco, beds of greyish-blue clays and yellow sandstone dip to the 
east at angles of ten or twenty degrees. Near Sheep’s spring Mr. Marcou saw the clays and 
the red sandstone of the “Trias” rising underneath similar strata and dipping to the east at a low 
angle. This inclination is shown in a small sectional representation accompanying the notes, 
November 13. The formation, however, on this part of the line appears to be generally hori¬ 
zontal, or nearly so. Near Camp 67, on the east side of the summit of the pass in the Sierra 
Madre leading to Zuni, there are, according to Mr. Marcou, very well developed red Triassic 
sandstones, dipping S.S.E. Beyond the mountains, and in the valley of Zuni, the “Trias” 
inclines towards the east, at an angle of from ten to fifteen degrees. North of this place, and 
in the line of trend of the Sierra Madre, the red strata are, according to Mr. Campbell’s state¬ 
ments, strongly uplifted, and dip eastward and westwardly. The edges of the strata may be 
seen about Fort Defiance in high bluffs. This is a region where trap dykes abound, a large 
one being found near the fort. 
At many points west of those last mentioned, the beds of the gypsum formation were found 
to be upraised at slight angles dipping east, west, or north, but. these angles in no instance were 
greater than ten degrees. Mr. Marcou refers the disturbances to three lines of dislocation. The 
dip along the Colorado Chiquito is from eight to ten degrees northward, and the strata were, to 
all appearance, dipping away from the Sierra Mogoyon, where the plateau seemed to end, the 
surface being gently ascending in that direction. 
We thus find that the line of greatest disturbance or inclination of the strata of the formation 
is on the eastern side of the Albuquerque and Gold mountains, where it reaches forty and sixty 
degrees. The inclination at other points seldom is as great as fifteen degrees. The principal 
disturbance appears to be confined to one line, and this a line of erupted trappean rocks in the 
form of dykes, whose presence is a sufficient explanation for the dislocations of the strata. So, 
also, at Fort Defiance, where the uplifts are great., we find trap dykes, which are conspicuous 
features in the scenery of the region. The flexures along the Washita and the Canadian, 
