GEOLOGIC RECONNAISSANCE OF TAOS RANGE 737 



Two pre-Cambrian inliers that cannot be classified outcrop on 

 Pueblo Creek. Quartz and mica schists and some amphibolite 

 are the only rocks in these inliers seen by the writer. 



CARBONIFEROUS SEDIMENTARY ROCKS 



In the district mapped all sedimentary rocks belong to the 

 Pennsylvanian series. Stevenson' described them as Carbonif- 

 erous, attempting no further divisions then. Later writers, espe- 

 cially W. T. Lee,^ who examined parts of this series farther east 

 and north, recognized them as belonging to the Pennsylvanian 

 series only. A number of fossils, collected by the present writer 

 near the base of the sedimentary series, belong to the Penn- 

 sylvanian fauna. Six species were identified: Lopophyllum 

 profundum, Siminula subtilita, Spirijer earner atus, Spirifer roeky- 

 montanus, Produetus eora, Produetus semiretieulatus . 



No generahzations concerning the thicknesses and divisions of 

 the series can be given in this paper with the exception of the state- 

 ment that by far the largest portion of the beds is composed of 

 clastic material. The lowest member is usually a basal con- 

 glomerate grading into a sandstone, but in some localities limestone 

 overHes directly the pre-Cambrian, and the sequence is reversed. 

 It is very common to see a limestone in sharp contact with a coarse 

 clastic in some places. On the other hand, formations hundreds 

 of feet thick are found in which the transitions from one member 

 into another are very gradual. Lithologically very similar beds 

 of clastic material occur at many different horizons of the series 

 and some of them are of such thickness that even considerable 

 displacements by faults may be easily overlooked. The fact that 

 all the faults seen by the writer in the sediments are normal and 

 that evidence of folding due to lateral compression is absent seems 

 to indicate that the Taos Range, if not the whole Sangre de Cristo 

 Range, was formed solely by intrusive activity, probably in early 

 Tertiary time. 



' Op. cit. 



2 W. T. Lee, "Geology and Paleontology of Raton Mesa and Other Regions in 

 Colorado and New Mexico," Prof. Paper loi (1918), pp. 41-42. 



