328 



SHORTER CONTRIBUTIONS TO GENERAL GEOLOGY, 1916. 



west of longitude 107° 30'. The beds here dis- 

 cussed were also referred by Shaler to the Lara- 

 mie without qualification, on the basis, it is 

 stated, of fossils studied by T. W. vStanton and 

 F. H. Knowlton, though the evidence is not 

 presented in detail. On looking over the origi- 

 nal reports on the plants collected by Shaler and 

 others in this region, I find that they were few 

 and fragmentary collections ordy, and the ten- 

 dency was to regard them as mainly older than 

 Laramie. 



The status of the "Laramie" in the region 

 under consideration was so well summed up 

 by Lee ' in 1912 that his statement is quoted 

 entire as follows: 



The "Laramie" formation occurs within the area 

 described in this paper only in the San Juan Basin. It 

 is more than 1,000 feet thick in the southern rim of the 

 basin but is thiimer in the eastern rim, probably due to 

 post-Cretaceous erosion. At Dulce it is only 225 feet 

 thick. The formation lies conformably on Lewis shale 

 and probably for this reason more than any other has been 

 called Laramie, although Dr. Cross several years ago called 

 attention to the fact that investigation had ' ' failed to bring 

 to light vaUd ground for assigning any of the beds in ques- 

 tion to the Laramie, wliile there is some reason to believe 

 that more than the lower sandstone belongs to the Mon- 

 tana group." Since that time a considerable number of 

 fossils, both of invertebrates and of plants, have been 

 collected from these beds in the Durango region. The 

 base of the formation^the Pictured Cliff sandstone — con- 

 tains marine invertebrates, and the lower part of the 

 coal-bearing rocks above this sandstone contains brackish- 

 water invertebrates, several of which occiu- in the Mesa- 

 verde of other fields. But liigher in the formation the 

 rocks contain fresh-water invertebrates wluch Dr. Stanton 

 regards as Laramie and fossil plants wliich Dr. Knowlton 

 regards as older than Laramie. The fossil plants have 

 been given in the table * * * and from this table 

 as well as from the accompanying statement by Dr. Knowl- 

 ton [see below] it will be seen that the flora differs but 

 little from that of the Mesaverde farther to the south. 

 The name "Laramie" is here used for this formation not 

 because the writer wishes to argue for the Laramie age 

 of the rocks, but because the name is in use and because 

 in tliis paper the writer is intentionally avoiding the 

 introduction of new names for rock formations. It must 

 be noted, however, that while the formation is called 

 "I^aramie " it contains a flora wliich denotes Montana age, 

 having notliing in common with the Laramie flora of the 

 Denver Basin. 



The statement by me to which Lee alludes 

 is as follows : n 



Near Dulce, N. Mex., and near Durango, Colo., there 

 have been obtained two collections of plants from above 

 the Lewis shale in coal-bearing rocks that have been 

 referred to the so-called "Laramie " of this region. These 

 collections are very full and embrace a number of easily 



' Lee, W. T., Stratigraphy of the coal fields of northern New Mexico: 

 Geol. Soc. America Bull., vol. 23, pp. 607-fl08, 1912. 



recognized species; hence their identification is satis- 

 factory and complete. These collections prove clearly 

 that these beds do not belong to the Laramie, since, so 

 far as known to the writer, not a single species there present 

 has been found in beds of tliis age. On the other Iiand, the 

 plants indicate beyond question that they belong to the 

 Montana, there being, for instance, Ficus spedosissima, 

 Ficus sp. (narrow, tliree-nerved type), Ficus sp., type of 

 F. lanceolala, a palm, etc., wliich link them with the 

 Mesaverde floras to tlie south and the beds aheady dis- 

 cussed in the Raton Mesa region. Associated with these, 

 however, and tending to give them a sUghtly higlier posi- 

 tion, though still witliin the Montana, are such forms as 

 Brachyophyllum, Cunninghamites, Cieinitzia, Sequoia, 

 etc., all of wliich are beyond doubt Montana types not 

 found in the Laramie. 



A number of collections were made by J. H. Gardner 

 in the Ignacio quadrangle, east of Durango, Colo., from 

 beds regarded as the Laramie of that area. The plants 

 in these collections, almost species by species, are iden- 

 tical with the forms from near Dulce and near Durango, 

 and I have no hesitation in saying that they occupy the 

 same stratigraphic position and are of the same age, viz, 

 Montana. 



It now remains to consider certain dinosaur- 

 bearing beds first reported near Ojo Alamo, 

 N. Mex., which may have a bearmg on the 

 "Laramie" of the San Juan Basin region. 

 In 1908 James H. Gardner, then of the United 

 States Geological Survey, found reptilian 

 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.^ These remains were 

 studied, by C. W. GUmore, who states that this 

 famia "appears to represent a typical fauna 

 of the so-called Laramie or better Ceratops 

 beds." 



It appears that dinosaiu- remams had been 

 known at the Ojo Alamo locality as early as 1902, 

 but it was not imtil 1904 that a systematic 

 attempt was made to collect them. In this 

 year Barnmn Brown, of the American Museum 

 of Natural History, made a reconnaissance 

 trip to the locality and obtained "a small 

 but interesting collection of fossils." These, 

 however, were not described in print until 

 1910.' Concerning the stratigraphic relations 

 of these beds Brown says: 



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

 Puerco formation rests unconformably on a conglomerate 



- Gardner, J. H., in Knowlton, F. H., The stratigraphic relations and 

 paleontology of the "Hell Creek beds," "Ceratops beds," and equiva- 

 lents, and their reference to the Fort Union formation: Washington 

 Acad. Sei. Proc, vol. 11, p. 32.3, 1909. 



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

 with description of the dinosaur genus Kritosaurus: Am. Mus. Nat. 

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



