Art. v.] Herrick, Geology of New Mexico. lot 
the mesa flora to rise to near the summit. A deep canon in the 
north end known as Placitos canon serves to collect the water 
from the northern part of the range and forms a most fruitful 
valley. 
The Tijeras canon on the south cuts the range abruptly off 
and the whole area from this canon to a point some miles south 
of Canon Largo, a distance of at least ten miles, has dropped 
out of conformity with the portion of the range both to the 
north and to the south. 
The cause of the fracture in the case of Tijeras canon 
is not far to seek but consists in a massive upthrust of a 
quartzose rock which passes obliquely across the range from 
southwest to northeast, terminating at the western end in the 
neighborhood of Coyote springs and at the eastern extremity 
in the vicinity of Whitcomb’s springs. It is a curious fact that 
the opposite ends should give rise to nearly the same conditions, 
the springs in both cases being highly mineralized. At Coyote 
especially the springs are highiy carbonated. 
The following is the result of the analysis of a sample of 
Whitcomb spring water by Prof. Randolph W. Tinsley, of the 
University of Mexico: 
Sodium Chloride, grains per gallon 
Calcium Sulphate, grains per gallon 
' Calcicum Carbonate, grains per gallon 
Magnesium Carbonate, grains per gallon 
Total 
The width of this axial dyke varies from 25 to over 50 
feet, and it is flanked by metamorphic rocks like hornblende 
and mica schists and diorite. Near the eastern end of the 
canon the schist and diorite come into close proximity to the 
limestone and the latter is greatly faulted and dislocated. At 
the east end of the canon the strata of the Jura-triassic and 
Cretaceous abutt upon the Carboniferous, so that the town of 
Tijeras is on the Jura-triassic area. 
.1927 
1.4360 
8.1896 
1.5188 
11-3371 
