390 Gordon and Graton — Formations in New Mexico. 



Art. XXXY. — Lower Paleozoic Formations in New Mex- 

 ico;* by C. H. Gordon and L. C. Graton. 



Students of New Mexico geology have hitherto generally 

 agreed in asserting the absence of the older Paleozoic forma- 

 tions in that region. Endlich,f followed by Clark,^: considered 

 certain limestones and quartzites occurring at the base of the 

 sedimentary section of Lake Yallej r , Sierra County, to be 

 Silurian, and some quartzites east of the Sandia Mountains, in 

 Sandoval and Bernalillo counties, have been regarded, probably 

 erroneously, as Cambrian. § With these and possibly a few 

 other exceptions, it has commonly been stated that rocks rep- 

 resenting the Lower Paleozoic periods are wanting in the 

 Territory, and that the Carboniferous formations rest directly 

 on granites, gneisses and schists, which are generally considered 

 to be pre-Cambrian, although in some cases the granites are 

 thought to be of later age. This prevailing view has recently 

 been summarized as follows : 



" At present there is no reliable evidence that any of the 

 Lower Paleozoic beds are represented within the limits of 

 New Mexico. The great Cambrian, Silurian, Ordovician and 

 Devonian systems which are so extensively developed in other 

 parts of the American continent have thus far failed to be 

 observed in the southern Rocky Mountain region." | 



Herrick states that in southwestern New Mexico occur 

 strata supposed to be older than the Burlington ' w some of which 

 have been referred to the Devonian (Hamilton)," but adds that 

 " as far north as Socorro County the stratified rocks overlying 

 the granite have revealed no remains indicating an earlier age 

 than the Carboniferous, and the writer knows of no positive 

 datum representing anything older than the Coal Measures.*^ 



During the past season a reconnaissance study of the mining 

 districts of New Mexico was carried on by the U. S. Geologi- 

 cal Survey under the direction of Mr. Waldemar Lindgren. 

 In the prosecution of this study many facts of stratigraphic 

 significance were obtained, and it soon became evident that in 

 certain places ,pre-Carboniferous .strata are present. Although 



* Published by permission of the Director of the U. S. Geo 1 ogical Survey. 



f The mining regions of southern New Mexico. Am. Nat. , vol. 17, pp. 

 149-157, Feb. 1883. 



\ The silver mines of Lake Valley, N. M., Trans. A. I. M. E., vol. 24, 1895, 

 pp. 188-167. 



SYung and McCaffery, Trans. A. I. M. E., vol. 33, p. 354, 1903. 



I Keyes, C. R., Geological formations of New Mexico, Report of Governor 

 for 1908, p. 338. See also U. S. G. S., Water Supply Paper No. 123, p. 20, 

 1905. 



TT Herrick. C. L., A Coal Measure forest near Socorro, N. M., Journal 

 Geol., vol. xii, p. 238, Apr. -May, 1904. 



