HISTORICAL REVIEW OF THE LARAMIE PROBLEM. 



71 



water origin and admittedly unreliable for purposes of 

 correlation, and that the plants are of Montana types, 

 serious doubt is cast on the Laramie age of the formation. 



It now remains to consider certain dinosaur- 

 bearing beds near Ojo Alamo, N. Mex., 12 

 miles south of Farmington, which may have a 

 bearing on the "Laramie" of the San Juan 

 Basin. In 1908 James H. Gardner, then of 

 the United States Geological Survey, found 

 vertebrate remains near the head of Coal 

 Creek, 1 mile southeast of Ojo Alamo, "in 

 variegated sands, shales, and conglomerates, 

 indisputably above the unconformity at the 

 top of the Laramie." 53 These remains were 

 studied by C. W. Gilmore, who reported the 

 presence of Triceratops, Trachodon, Tyranno- 

 saurus, Aspidiretes, and crocodiles, which, he 

 said, "appears to represent a typical fauna of 

 the so-called Laramie, or better, Ceratops 

 beds." At the time this was written it was 

 thought possible that these dinosaur-bearing 

 beds might be a part of the Puerco formation, 

 but subsequent investigation has shown that 

 this is not so. 



In the same year (1909) Stanton bi listed 

 several collections of invertebrates from the so- 

 called Laramie "coal measures immediately 

 above the Lewis shale," on the line between La 

 Plata and Archuleta counties, Colo., which he 

 considered as belonging to the same fauna and 

 "at about the same horizon" as the fauna in 

 the beds at Black Buttes, Wyo. 



It appears that dinosaurs had been known 

 at the Ojo Alamo locality as early as 1902, but 

 it was not until 1904 that a systematic attempt 

 was made to collect them. In that year 

 Barnum Brown, of the American Museum of 

 Natural History, made a reconnaissance trip to 

 the locality and procured "a' small but inter- 

 esting collection of fossils." His report on 

 these fossils, however, was not published until 

 1910. 55 He said: 



This collection is of special interest, as it represents a 

 fauna that is distinctly older than that of the "Lance 

 Creek beds or Ceratops zone" and "Hell Creek beds" of 

 the Laramie Cretaceous. I am unable definitely to 

 correlate the horizon in which these bones occur, but 



» ICnowlton, F. EL., The stratigraphic relations and paleontology of 

 the "Hell Creek beds," " Ceratops beds," and equivalents: Washington 

 Acad. Sei. Proc, vol. 11, p. 233, 1909. 



" Stanton, T. W., The age and stratigraphic relations of the " Ceratops 

 beds" of Wyoming and Montana: Washington Acad. Sci. Proc, vol. 11, 

 p. 274, 1909. 



» Brown, Barnum, The Cretaceous Ojo Alamo beds of New Mexico, 

 with description of the new dinosaur genus Kritosawus: Am. Mus. Nat. 

 Hist. Bull., vol. 28, pp. 267-274, 1910. 



the faunal fades appears to be even older than that of 

 Black Buttes, Wyo., and probably represents a period 

 synchronous with the lower part of the Edmonton series 

 of Alberta, Canada. * * * 



Less than a mile south of the store at Ojo Alamo the 

 Puerco formation rests unconformably on a conglomerate 

 that is composed of red, gray, yellow, and white pebbles. 

 The position of these beds is below what may be called 

 the type of the Puerco or basal Eocene, and their uncon- 

 formable relation is highly significant. * * * Below 

 the conglomerate there is a series of shales and sandstones ( 

 evenly stratified and usually horizontal, in which there is 

 much less cross-bedding than commonly occurs in the 

 Laramie of the northern United States. 



The shales below the conglomerate that contain numer- 

 ous dinosaur and turtle remains I shall designate as the 

 Ojo Alamo beds. They are estimated to be about 200 feet 

 thick, but owing to lack of time I was unable to deter- 

 mine their relation to the underlying formations. The 

 vertebrate remains were numerous in several places from 

 30 to 100 feet below the conglomerate. 



The new dinosaurian was described as 

 Kritosaurus navajovicus. 



During the summer of 1909 James H. Gard- 

 ner, in company with James W. Gidley, of the 

 United States National Museum, spent two 

 days in the vicinity of Ojo Alamo and obtained 

 a number of remains of turtles from Brown's 

 Ojo Alamo beds. These were described by 

 O. P. Hay 56 the following year. Concerning 

 the stratigraphic relations Hay said : 



In this region they found two distinct formations. In 

 the lower, composed of sandstones, clays, and a bed of 

 conglomerate, there were found fragmentary remains of 

 dinosaurs and the turtles below described. * * * These 

 beds are probably the equivalent of the Lance Creek 

 beds. 



Also in 1910 Gardner" published a paper 

 on "The Puerco and Torrejon formations of 

 the Nacimiento group," which involved, inci- 

 dentally, the beds under discussion. He re- 

 corded the Puerco as resting unconformably on 

 the "Laramie" of the region, as Brown had re- 

 ported, and he stated that at Ojo Alamo he 

 " obtained dinosaurs from beds unconformably 

 above the 'Laramie' and below the. Wasatch." 

 These beds are, of course, the Ojo Alamo beds 

 of Brown, and Gardner's discovery tended to 

 establish the fact that these dinosaur-bearing 

 beds rest unconformably on the "Laramie" 

 and are unconformably overlain by the Puerco. 



An expedition from the American Museum 

 of Natural History, under the charge of W. J. 



* Descriptions of eight new species of fossil turtles from west of the 

 one hundredth meridian: TJ. S. Nat. Mus. Proc. r vol. 38, pp. 307-326, 

 1910. 



5' Gardner, J. H., Jour. Geology, vol. 18, pp. 702-741, 1910. 



