102 



LARAMIE FLORA OF THE DENVER BASIN. 



south of Golden. A discussion of its reported 

 presence at Point of Rocks and Black Buttes, 

 Wyo., will be found in the systematic treat- 

 ment of the species (p. 134). Ficus denveriana 

 (F. spectabilis Lesquereux) is essentially a 

 Denver species, and its occurrence in the Lara- 

 mie depends on a doubtfully determined leaf 

 from Popes Bluff, near Colorado Springs. 

 Dombeyopsis obtusa Was first obtained from the 

 Laramie at Popes Bluff and has since been 

 noted in the Lararnie at Coal Creek, Marshall, 

 Hoyt's mine, south of Golden, and Crow Creek, 

 northeast of , Greeley; in the Dawson arkose at 

 Pulpit Rock; and in the Denver at the Douglas 

 coal mine, Sedalia. Though it is more abundant 

 in the Laramie it is undoubtedly present in the 

 post-Laramie beds as above indicated. Lau- 

 rus wardiana is a rare species, known posi- 

 tively only from a single leaf from Golden and 

 questionably in the supposed Dawson near 

 Mosby, Colo. Paliurus zizyphoidesw&s estab- 

 lished on material from Black Buttes, Wyo., 

 and was reported by Lesquereux to have been 

 found also in the Laramie at Erie and the sup- 

 posed Laramie at Sand Creek, Colo., but no 

 specimens from these localities are known to 

 exist. Rhamnus salicifolius was described from 

 material obtained in the Laramie at Marshall 

 and has since been found at Cowan station, near 

 Denver. Its presence in the Dawson arkose 

 depends on specimens from Templeton Gap, 

 near Colorado Springs. It also occurs in the 

 Vermejo formation, the Montana group of 

 Wyoming, and elsewhere. 



RELATIONS TO THE ARAPAHOE FORMATION. 



Before it will be possible to consider any 

 relation between the flora of the Laramie and 

 that of the Arapahoe, it will be necessary to 

 review with some care the .present status of 

 knowledge concerning the Arapahoe flora. 

 According to Eldridge, on whom largely de- 

 volved the task of studying the Arapahoe 

 formation for the Denver Basin monograph, 

 the formation was found to contain poorly 

 preserved fossil leaves at a number of localities 

 within the Denver region, but no determinable 

 species were collected. Only two localities 

 were known from which determinable plants 

 supposed to be of Arapahoe age have been re- 

 ported — Sand Creek, east of Denver, and the 

 vicinity of the Douglas coal mine, Sedalia, 

 about 20 miles south of Denver. 



Some 9 or 10 species of plants are recorded 

 as having come from the Sand Creek locality, 

 all of which were obtained by the earlier 

 workers in this field — that is, probably about 

 1873. Considerable uncertainty has exfsted as 

 to the exact locality whence these plants came, 

 but apparently important light is thrown on 

 this point by a chance statement made by A. R. 

 Marvine " in his paper on "The geology of Mid- 

 dle Park," which on account of its importance 

 is quoted entire below. 



East of Denver, in T. 4 S., and probably between Rs. 

 65 and 66 W;, a shaft has been sunk for some depth in a 

 high bank on the south side of Sand Creek but is now 

 abandoned. The coal also outcrops on the bank and there 

 appears as of very poor quality. Fossil leaves are abun- 

 dant. ( 



It was near here that the first discoveries of coal were 

 made in Colorado, and the stream at this point is often 

 known as Coal Creek, though called Sand Creek further 

 down. The latter name should be retained, to prevent 

 confusion between this and the better^known Coal Creek 

 on the west side of the Platte. 



About 4 miles to the north, near Box Elder, on the Kansas 

 Pacific Railroad, in R. 65 W., T. 3 S., sec. 28 (?), and 

 probably at the same horizon as the last, are two shafts 

 which reach coal and on which work has been done now 

 and then for some years. It is probably in one of these 

 three shafts that the following section was made by 

 Mr. E. B. Mally (quoted by Lesquereux in Hayden's 

 report for 1872, p. 327), and which seems to give an idea 

 of the strata near here. * * * 



The work was abandoned on account of the poor quality 

 •of the coal. 



That the above-indicated plant-bearing hori- 

 zon is probably the important one in the present 

 consideration was still further indicated by 

 Marvine, who, after mentioning a number of 

 coal openings in another direction from Denver, 

 said: "The only others I have heard of lie 

 from 15 to 17 miles east of Denver City and near 

 the Box Elder station on the Kansas Pacific 

 Railroad." The assumption seems to be 

 justified, therefore, that the plants labeled 

 "Sand Creek" probably came from this area. 



In Lesquereux 's "Tertiary flora" the fol- 

 lowing data are recorded concerning six of the 

 species reported to have come from Sand Creek: 



Lastrea (G.) polypodiodes. Sand Creek (W. H. Holmes). 

 Gymnogramma gardneri. Roof of a coal mine, Sand 



Creek (A. Gardner). 

 Equisetum laevigatum. Sand Creek, 8 feet above coal 



(W. H. Holmes). 

 Eriocaulon? porosum. Sand Creek (W. H. Holmes) with 



leaves of Nelumbium. 



« U. S. Geol. and Geog. Survey Terr. Kept, for 1873, pp. 120, 121, 1874. 



