illi: LARAMIE GROUP. 

 BY .1. s. NEWBERRY. 



(Abstract.) 



The Laramie group was named by Mr. Clarence King and defined in his "Sys- 

 tematic Geology," volume I of the Report on the Geology of the Fortieth Parallel, 

 L878. The name was accepted by Dr. Hayden bul differently applied, since, contrary 

 to the usage and judgment of Mr. King, he included in it the Fort Union group. 

 Dr. Hayden at first called his compound Laramie Tertiary, but he subsequently desig- 

 nated it post-Cretaceous. 



The Laramie group proper, as defined by King, consists of a series of Bhales, sand- 

 stones, and I"-'!- of coal, largely developed in Colorado, Utah, and Wyoming. It is 

 well exposed on the east Bide of the Rocky .Mountains in a belt that reaches as far 



north and south as explorations have I n made I have myself traced it nearly to 



the southern line of Chihuahua and as far north as the Canadian boundary : through- 

 out this region it is a greal coal-bearing belt. Along tin' line of tin' Pacific railroad 

 it is exposed at Point of Rocks, Black Butte, Bitter Creek, Evanston, and elsewhere, 

 and tli>' coal mini'- at the-'' places are -ill opened in it. On the west side of the Rocky 

 Mountains also it is coal-bearing, and is known to extend interruptedly from the San 

 Juan river to and beyond the Union Pacific railroad. At Crested Buttes, Coal Basin, 

 Newcastle, and other points it contains a number of thick and very pure coals 

 which vary in character from hard, bright anthracite to non-coking bituminous coals, 

 this variation being dependent upon igneous rocks which sometimes cut through, 



times underlie, and sometimes have overflowed the coal beds. Pr tin' Rocky 



Mountain- in < lolorado th^ Laramie extends westward to the Wasatch, and everywhere 

 contains beds of coal, some of which have been worked at Cedar City, Castle Valley, 

 Pleasant Valley, Coalville, and elsewhere. 



'I'll'' Laramie formation has in the Raton mountain, according to Mi-. R. c. Hills, 

 a thickness of nearly 6,000 feet. At Trinidad, Walsenburg, Florence, and north of 

 Denver at Marsballs's and at Erie, in all of which localities its coals are worked, it 

 i- much thinner, the upper portion having been removed by erosion. In Table 

 mountain, near Golden, this upper portion ha- been protected by a trap overflow, and 

 a thickness of perhaps 3,000 feet of strata is shown, all of which belongs to the Lara- 

 mie. <>n the west Bide of the K"*'ky Mountain-, at Coal Basin, Newcastle, and ''1-''- 



whore, the La rami'- shows a thicki of from 8,000 to 1,000 feel The beds are hero 



highly inclined; hut in Monument up '-a. between Grand river and the Gunnison, the 

 strata are nearly horizontal and are overlain unconformably by fresh-water Tertiary 



The relations "I the Laramie group have 1 n much discussed, and perhaps no por 



• , of the geological column of North America has given rise ton greater amount "i 



literature or a greater diversity of opinion among geologists. This, for the most part, 

 arisen from the fact that many writer- on tin- subject have combined two distinct 



formations in the Laramie and have called them one. when they have almost nothing 



in common, belong to different geological systems, and should never hav 3 boon united, 

 h K. V . Hayden, who spent so many years in studying the geology of tho country 



bordering tl IT'"' N ' '' made large collections of fossil plant- from the Port 



