HENDERSON] GEOLOOY AND TOPOGRAPHY 27 



further dissected by numbers of lateral streams, perennial and inter- 

 mittent, and has weathered in many places into "bad-land" monu- 

 mental and castellated forms. 



These Tertiary deposits, called the Santa Fe marls, were originally 

 assigned by Cope and Stevenson to the later (Pliocene) division of 

 the Tertiary sj^stem, but later writers consider them older, chiefly 

 Mocene.^ There is little doubt that strata of very different age have 

 been confused under one name in the area at present under considera- 

 tion, which may represent the time from ISIiocene to Recent. 



Early writers agreed in supposing that all the beds designated Santa 

 Fe marls were deposited in a great lake, but if any definite evidence 

 inchcating such origin has been published the writer has overlooked it. 

 An examination of the various descriptions of the formation, as well 

 as Ms own brief examination near Buckman, has convinced the writer 

 that the evidence points to fluviatile and eolian origin. _ 



Johnson ^ assigned the Santa Fe formation to subaerial origin and 

 did not separate it from the Quaternary. In the abstract of a paper 

 read in 1905, which abstract was. not published until 1907, Keyes ^ 

 was made to say: 



Tlie recent ascribing of a fluviatile origin to most of the Tertiary formations of the 

 region is l)elieved to he erroneous, and is d^ie^rgely to a confusion of Quaternary 

 deposits with more recent Tertiary lieds. 



In a paper under the same title read before the Iowa Acadeni}- of 

 Science early in 1905 and published late in the same year, the same 

 objection does not appear, a circumstance from which it is fair to 

 assume that he has accepted the more recent view of the origin of 

 these beds or at least does not consider his former objection tenable. 

 Extensive deposits of approximately the same age elsewhere were at 

 first attributed to lakes, but are now believed to be of fluviatile 

 origin. 



After the deposition of at least part of the beds that liave been 

 included in the Santa Fe formation, probably followed by some 

 erosion, there came a period of tremendous volcanic activity, which 

 resulted in spreading a thick sheet of volcanic tuft" (tufa) over a 



1 Cope, E. D., Notes on the Santa Fe Marls and some of the Contained Vertebrate Fossils, in Proc. 

 Acad. Nat. Sci. Phila., xxvi, 147-52, 1S74; The Extinct Vertebrata Obtained in New Mexico by Parties 

 of the Expedition of 1874, in U. S. Geol. Ezpl. & Surv. W. of 100th Merid., Final Rep. iv, pt. n, 20, 1877; 

 Stevenson, John J., Systematic Geology, ibid., m, suppl., pt. n, 102-6;^, 1881; Reagan, Albert B., 

 Geology of the Jemez-Albuquerque Region, New Mexico, in Amer. Geol., xxxi, 67-111, 19a3; Dall, 

 Wm. H., and Harris, G. D., Correlation Papers— Neocene, in Bull. 84, U. S. Geol. Surv., 303, 1892; 

 Matthew, W. D., A Provisional Classification of the Fresh-water Tertiary of the West, in Bull. Amer. 

 ^fu.t. \at. Hist., xn, 05, 1899; Johnson, D. W., The Geology of the Cerrillos Hills, New Mexico, in School 

 of Mines Quarterly, xxiv, 329-32, 1903; Keyes, C. R., Tertiary Terranes of New Mexico, in Proc. Iowa 

 Acad. ScL, xiv, 223, 1907; Osbom, H. F., Cenozoic Mammal Horizons of Western North America, in 

 Bull. S61, U. S. Geol. Surv., 05, 1909; Osborn, The Age of Mammals, p. 298, 1910. 



2 Johnson, D. W., op. cit., pp. 325-29, 1903. See also Lee, Willis T., Water Resources of the Rio Grande 

 Valley in New Mexico and Their Development, in U. S. Geol. Surv., Water Supp. and Irr. Paper no. 188, 

 p. 20, 1907. 



3 Keyes, C. R., Tertiary Terranes of New Mexico (abstract), Bull. Geol. Soc. Amer., xvii, 725, 1907; 

 also a paper (in full) under same title in Proc. loua Acad. Sci., xiv, pp. 223-28, 1907. 



