72 



LARAMIE FLORA OF THE DEN^^;R BASIN. 



Sinclair and Walter Granger,'* spent the, 

 seagon of 1913 in collecting fossils from the 

 Puerco and Torrejon formations of New Mex- 

 ico. Although these authors were concerned 

 mainly in procuring mammal remains from 

 the formations mentioned, they recorded cer- 

 tain important observations on the under- 

 lying dinosaur-bearing or Ojo Alamo beds. 

 They agreed with Brown and Gardner in find- 

 ing the Puerco resting with marked erbsional 

 discordance on the underlying beds. The rep- 

 tilian and other vertebrate material procured 

 by Sinclair and Granger from the Ojo Alamo 

 beds was studied by Brown, whose report they 

 quoted. From this it appears that Brown's 

 KrUosauriDi was regarded as generically iden- 

 tical with Gryposaurus, described later by 

 Lambe '' from the Belly River formation of 

 Canada. Continuing, Brown said: 



The fauna of the Ojo Alamo beds is certainly older than 

 that of the Lance, and I have expressed the opinion that 

 it is probably synchronous w-ith the Edmonton. Krito- 

 saitrus is now known from the Belly River beds and has 

 not yet appeared in extensive collections from the Ed- 

 monton, and as other reptilian remains are of primitive 

 facies the Ojo Alamo beds may well be of Judith River age. 



Sinclair and Granger did not attempt to 

 reach any decision concerning the age of the 

 Ojo Alamo beds, though they gave an alterna- 

 tive hypothesis, as follows : 



Willis T. Lee favors a correlation of the dinosaur beds 

 and associated conglomerate members with the Animas 

 formation. If the Animas is in turn to be correlated with 

 the Lance, * * * then the line between Cretaceous 

 and Tertiary in the Ojo Alamo region would have to be 

 drawn * * * not at the unconformity below the 

 Puerco, where the vertebrate paleontologist would incline 

 to put it, but at some level not yet discovered. 



The probable correlation of the Ojo Alamo 

 beds was suggested by me '"' as follows : 



The Puerco formation rests unconformably on dinosaur- 

 bearing beds, beneath which is the "Laramie' of the 



" Paleocene deposits o( the San Juan Basin, N. Mex.: Am. Mus. Nat. 

 Hist. Bull., vol. 33, pp. 297-316, 1914. 



» Lambe, L. M., Ottawa NaturalLst, vol. 27, p. U.i, 1914. 



«' Knowlton, F.H.,Creta?eou5-Tortiaryboundaryinthe Rocky Moim- 

 tiin region: Geol. Soc. .\merica Bull., vol. 2.), p. 338, 1914. 



region. I have .shown elsewhere, however, that these 

 later beds are undoubtedly much older than Laramie. 

 The "Ceratops beds," immediately beneath those con- 

 taining the Puerco fauna, have been practically traced 

 into the Animas formation, which Cross holds is of Denver 

 age. The .\nimas formation is now known to extend east- 

 ward to the eastern border of the San Juan Basin, near 

 Dulce, N. Mex., where it is conglomeratic at the base and 

 consists of an andesitic matrix, in which are pebbles of 

 many kinds of older rocks; above this conglomerate are 

 Eocene leaves. 



The last published contribution to the geol- 

 ogy and paleontology of the San Juan Basin 

 was made in 1916, when four short papers by 

 C. M. Bauer, C. W. Gilmore, T. W. Stanton, 

 and me were issued under the general caption 

 "Contributions to the geology and paleontology 

 of San Juan County, N. Mex." "" The first paper 

 of the series, bj' Bauer, was entitled ''Stratig- 

 raphy of a part of the Chaco River valley" and 

 was based on field work and collections made 

 in 1915. The thesis of Bauer's paper he gave 

 as "an attempt to set forth the principal features 

 of the stratigraphy in a part of the San Juan 

 Basin — to describe the succession of strata 

 irrespective of possible correlations and thereby 

 to establish a type section for the formations 

 exposed and to bring out their relations to the 

 strata immediately above and below." 



In the complex generally designated by 

 previous writers as Laramie Bauer was able to 

 differentiate two additional formational units. 

 The lower of these, called the Fruitland forma- 

 tion, rests conformably on the Pictured Cliffs 

 sandstone, has a thickness of 49 to 275 feet, 

 and contains the coal of .the region. Conform- 

 ably above this formation is the Kirtland shale, 

 with a maximum thickness of 1,1S0 feet and 

 including what is called the Farmington sand- 

 stone member, which reaches a thickness of 455 

 feet. Above the Kirtland is the Ojo Alamo 

 sandstone of Brown. The relation between 

 the newer and older interpretations was shown 

 in the following table : 



•'U.S. Geol. Survey Prof. Paper 98, pp. 271-353, 1916. 



