646 W. T. LEE STRATIGRAPHY OF COAL FIELDS OF NEW MEXICO 



Feet 



Shale, carbonaceous 10 



Sandstone 6 



Intruded lava sheet 10 



Shale 4 



Coal 2 



Shale 3 



66 4- 



The rocks of this section lie stratigraphically below the Galisteo sand- 

 stone and above the intrusive sheet of igneous rock that overlies the 

 highest or White Ash coal bed at Madrid. The thickness of this intruded 

 rock is shown in the accompanying records of drill-holes. A diamond 

 drill prospect was made in the gulch a few hundred feet northeast of the 

 old mine just mentioned and about 4,500 feet east of the principal open- 

 ing at the outcrop of the White Ash coal bed. The drill penetrated some- 

 thing like 75 feet of rock that seems to belong to the Galisteo sandstone 

 before it reached the coal-bearing rocks of the Mesaverde, and then en- 

 countered beds that seem to be equivalent to those of the section just 

 given. After passing through the igneous rock, a group of coal beds was 

 encountered that doubtless is the same as those opened at Madrid. The 

 record is platted to scale in the third column of figure 5, on page 644. 



A second drill-hole was put down 6,800 feet east of the outcrop of the 

 White Ash coal bed. The drill reached a depth of 1,602 feet and pene- 

 trated not only the beds represented in the first record, but those of strati- 

 graphic horizons considerably lower. The Galisteo sandstone occupies 

 the surface in this region, but there is nothing in the record to indicate 

 its thickness at this locality except the red or variegated color, which, 

 however, may be caused by the metamorphic action of the intrusive igne- 

 ous rock. Since no coal is known to occur in the Galisteo sandstone, it 

 seems safe to draw the line of separation between this formation and the 

 Mesaverde above the highest coal bed, as has been done in figure 5. 

 This record shows the occurrence of three groups of coals. The highest 

 group obviously corresponds with that represented by the beds under- 

 neath the sheet of intrusive rock in the first record and to those of the 

 Madrid section. The two lower groups probably correspond in strati- 

 graphic position to those described later near Omera farther east and to 

 the lower coals near Eogers west of Madrid. The record is platted to 

 scale in the second column of figure 5. 



The dip of the rocks, which is 15 degrees east at Madrid, if unchanged 

 would soon carry a given bed to a considerable depth. However, the 

 dip no doubt lessens eastward toward the center of the basin, and it is 



