DESCRirTivE details: tijeras coal field 629 



Feet Inches 



Shale, yellow to chocolate-colored 57 



Shale, carbonaceous 5 



Sandstone, massive, yellow (Punta de la Mesa sandstone), con- 

 taining Inoceramus deformis Meek?; Avicula sp. ; Mactra sp. ; 

 Cardium sp. ; Anisomyon? sp. ; Cyprimeria? sp. (U. S. G. S. 

 locality Nos. 3514 and 3519) 77 



1,703 8 



TIJERAS COAL FIELD 



The Tijeras coal field is located in central New Mexico, about 14 miles 

 south of Hagan and 20 miles east of Albuquerque, on the eastern slope 

 of the Sandia Mountains. The coal-bearing rocks occupy the center of a 

 syncline of irregular outline about 5 miles long and, 2 miles wide (see 

 figure 4), lying between the Sandia uplift on the west, the South Moun- 

 tain uplift on the northeast, and a broad but less well defined uplift on 

 the southeast, which manifests itself within the area mapped by a fault 

 which brings the Carboniferous red beds in contact with the Mancos 

 shale. The coal-bearing rocks are much disturbed by faulting, warping, 

 and crushing, but in general dip from all directions toward the center of 

 the syncline. Along the western margin of the field the strata are up- 

 turned to a nearly vertical position. Across the edges of these upturned 

 beds at San Antonio the part of the accompanying section below the coal 

 beds was measured. In the central part of the syncline, although the 

 rocks lie more or less horizontal, they are warped, faulted, and crushed 

 to such an extent that any measurement of their thickness is likely to be 

 deceptive. The part of the accompanying section above the Mancos shale 

 was measured in a canyon at Holmes mine near the center of the syncline, 

 where the rocks seem to be disturbed less than they are in some other 

 places. Nevertheless, the section is given here with some hesitancy be- 

 cause the measured thickness may prove to be quite different from the 

 thicknesses of the beds as originally laid down. The section as measured 

 is as follows: 



