GEOLOGY OF THE LARAMIE PLAINS 



Lesquereux, in Hayden's Report for 1872, tells how 

 peat bogs are formed and discusses, in a full and interesting 

 manner, their formation, and also the Lignitic formations of 

 the Rocky Mountains. In this article he speaks of the coals of 

 New Mexico, Colorado and Wyoming. He says that the 

 Cretaceous, four miles west of Medicine Bow, passes under the 

 barren Lignitic sandstone. From this to Carbon the strata is 

 continuous in repeated undulations, forming basins, which 

 contain the Upper Lignitic, with remarkably thick beds of 

 combustible material. The shaft at Carbon shows: 



1 st^Clay shale and sandstone at top, 35 feet. 



2d — Ferruginous shale with dicotyledonous leaves, 3 feet. 



3d — Clay shale and sandstone, plants at top, 1 8 feet. 



4th— Main coal, 9 feet. 



5th— Fire clay, shale and dicotyledonous plants, 20 feet. 



6th— Coal, 4 feet. 



7th^Fire clay and shale, 8 feet. 



8th-Coal, 4 feet. 



In the above there are included 1 7 feet of coal in 1 1 feet of 

 depth. One mile west of Carbon, the upper coal is seen in a 

 cut under a thick layer of compact gritty sandstone with fossil 

 wood and streaks of coal near the base. Over the sandstones 

 are beds of fire-clay with silicified wood, and fossil dicotyledo- 

 nous leaves occur in the overlying shale. 



At Point of Rocks the Lignitic series overlies Cretaceous No. 

 4, these constituting the axis of an anticlinal. Dipping west the 

 Upper Lignite strata is brought to the surface at Rock Springs. 

 At Point of Rocks, 80 feet of the Cretaceous below the Lignitic 

 is exposed and this is conformably overlaid by 185 feet of 

 Lignitic sandstone, bearing fucoidal remains. Twenty-five 

 feet above the base of this sandstone there is a bed of coal 8 

 feet thick. 



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