84 



LARAMIE FLORA OF THE DENVER BASIN. 



During the summer of 1915 W. T. Lee ob- 

 tained evidence that the Seranton coal beds 

 are in the Denver formation rather than in an 

 upper division of the Laramie. He obtained 

 the record of a well put down near Sable station, 

 on the Union Pacific Railroad east of Denver 

 and a few miles west of Seranton. This well 

 is more than 3,000 feet deep and penetrated the 

 Seranton coal beds, the Arapahoe conglomerate, 

 the Laramie formation, the Fox Hills sandstone, 

 and nearly 1,500 feet of the underlying shale. 

 The record seems to establish the following 

 relations:'* 



1. The coal beds of the so-called upper divi- 

 sion of the Laramie occur in the Denver forma- 

 tion 200 to 450 feet above the top of the 

 Laramie. 



■ 2. At this point the Arapahoe conglomerate 

 is 50 feet thick. 



3. The Laramie formation is here 700 feet 

 thick with one thick bed of coal at the base. 



4. The sandstone which imderlies the Lara- 

 mie coal and which presumably represents the 

 so-called basal sandstone of the Laramie and 

 the sandstone at the top of the Fox Hills is 

 here only 160 feet thick. 



5. Below this Fox Hills sandstone the upper 

 part of the sandy fossiliferous shale may be of 

 Fox Hills age, but there seems to be no way of 

 distinguishing this part from the Pierre shale. 



ANIMAL LIFE OF LARAMIE TIME IN THE DENVER 

 BASIN. 



VERTEBRATES. 



If we are to judge from the remains that have 

 thus far been brought to light, animal life of all 

 kinds was exceedingly rare in the Denver Basin 

 during Laramie time. So far as I know only a 



" In a personal communication Lee states that the written log of the 

 upper part of this well to a depth of 1,300 feet could not be obtained, but 

 that the record of the beds below this depth is copied from the driller's 

 notes. The upper part of the record is based on the independently 

 procured statements of the driller and two other men who were 

 sufficiently interested to keep themselves constantly informed of the 

 progress of the well. The testimony of these three men agreed in all 

 essential points. They were questioned particularly in reference to 

 the Seranton coals and the conglomerate. The position of the beds of 

 coal can not be reasonably doubted, as they crop out east of the well and 

 are reported from numerous water wells in the vicinity of Sable. The 

 conglomerate was described as consisting of pebbles of ''quartz, flint, 

 black diamonds," etc., the largest an inch or more in diameter. Some 

 of the pebbles described as "black diamonds" had been preserved and 

 appear to consist of black chert. In response to a query as to the number 

 of the pebbles the statement was made that "bushels of them came out." 

 Lee afterward visited the locality near Morrison where these beds crop 

 out and found that the driller's description corresponded very closely 

 with the beds as they are exposed at the surface. All things considered, 

 the log seems to be as well authenticated as the average driller's record. 



single fragment of a vertebrate has been re- 

 ported from beds supposed to be of Laramie 

 age within this area. The occurrence of this 

 specimen was described as follows by G. H. 

 Eldridgei'^ 



The vertebrate, according to Prof. Marsh, belongs to the 

 order Ornithopoda of the subclass Dinosaiiria. The genua 

 is undetermined. The specimen was foimd by a ranch- 

 man about 30 feet below the surface, in a well sunk through 

 the upper Laramie strata, on the slopes of Dry Creek, 

 about 8 miles southwest of the town of Brighton. 



This locality is apparently about 10 miles 

 due north of Denver and according to the 

 geologic map accompanying the Denver Basin 

 monograph should fall within an area indicated 

 as Laramie. The betls were thought by Eld- 

 ridge to represent the upper part of the Laramie, 

 but in the light of the results obtained by Lee 

 (p. 103) only a few miles east of this Dry Creek 

 locality, it seems more than probable that this 

 supposetl upper Laramie belongs to the Denver 

 formation, in which case the bone came either 

 from the Denver or the Arapahoe. A depth of 

 only 30 feet below the surface would certainly 

 not reach the Laramie and would probably 

 place it in the Arapahoe, tvhich is well known to 

 contain vertebrate remains. Thus, to the un- 

 certainty of the biologic interpretation of this 

 fragment is added the indefiniteness of its 

 stratigraphic position, and it can be dismissed 

 as absolutely without value. 



INVERTEBRATES. 



The only remains of invertebrates recorded 

 from the Laramie of the Denver Basin by 

 Eldridge °° are Ostrea gJahra and Unio sp. ?, 

 determined by C. A. White. Eldridge said: 

 "The occurrence of Ostrea glabra is general for 

 the field and always at the same horizon, a 

 short distance above the basal sandstones of 

 the formation." 



Beds held to be of true Laramie age have 

 been found in the valley of Crow Creek, which 

 is about 25 miles east of Greeley and between 

 40 and 50 miles north a little east of Denver, 

 outside the strict limits of the Denver Basin 

 as accepted in the Denver monograph. This 

 region was visited by C. A. White " in 1877, 

 while he was attached to the Hayden Survey. 



» U. S. Geol. Survey Mon. 27, p. 77, 1896. 

 »«0p. cit., p. 78. 



1 Report on paleontological field work for the season of 1877: U. S. 

 Geol. and Geog. Survey Terr. Eleventh Ann. Rept., pp. 163-175, 1879. 



