DESCRIPTIVE details: CERRILLOS FIELD 643 



for many years. The coal-bearing rocks occupy a syncline between the 

 Ortiz Mountains and Galisteo Creek and extend from the town of Galis- 

 teo westward for a distance of about 14 miles. The syncline is unsym- 

 metrical and the rocks are warped and faulted in many places, but in 

 general they dip from all directions toward the center of the syncline. 

 The general geology of this .field has been described by D. W. Johnson 

 (83), and no space will be devoted to it in this paper farther than is 

 necessary for an understanding of the age and structural relations of the 

 Cretaceous and younger formations. The coal-bearing rocks are referred 

 to the Mesaverde and are correlated with those of the Hagan, Tijeras, 

 Eio Puerco, and Cabezon coal fields, as indicated in figure 2. 



The principal coal beds of the upper part of the Mesaverde formation 

 have been opened at Madrid and their thickness, character, and strati- 

 graphic position are well known from mining operations. Coal has been 

 mined from three beds, the lowest of which, known as the Cook and White 

 coal bed, averages 3 feet in thickness. One hundred feet stratigraphic- 

 ally above this is the Peacock coal bed, averaging 1 foot 8 inches in 

 thickness, and 22 feet higher is the White Ash coal, which normally con- 

 tains coking bituminous coal, averaging 5 feet 6 inches in thickness. Near 

 Madrid this White Ash coal has been changed to anthracite by the intru- 

 sion above the bed of a sheet of igneous rock 400 to 500 feet thick. The 

 anthracite coal averages 3 feet in thickness. From data obtained in min- 

 ing and kindly furnished to the writer by Mr. G. A. Kaseman, the follow- 

 ing section of the coal-bearing rocks at Madrid has been constructed. 

 This section probably furnishes the best standard with which to compare 

 others measured in the Cerrillos coal field, although fossils are so scarce 

 as to be of little assistance in correlating other sections with it. 



Section of Rocks exposed at Madrid, New Mexico 



Feet Inches 



Intrusive igneous rock 



Shale, containing fossil plants ; Gcinitzia sp 5± 



Coal, White Ash bed 5 



Shale and sandstone 22 



Coal, Peacock bed 1 



Shale and sandstone 8 



Sandstone 20 



Shale 20 



Sandstone 20 



Shale with thin seams of coal 2 



Shale 6 



Sandstone 20 



Shale ,3 



Coal, Cook and White bed 3 



