Mesozoic and CcBiiozoic Geology and Paloiontology. 115 



feet, it is barren, too, of aD}^ remains of animals, while here and there 

 branches of fiicoids appear, as thrown by the waves, being generally 

 mixed with fragments of wood and stems of dicotyledonous plants. 

 From the cut of the railroad west of Medicine Bow, where this sand- 

 stone is seen overlying the Cretaceous, and where two fine mineral 

 springs come out from its base, it is continuous to Carbon, in repeated 

 and deeper undulations, forming basins, which at this place and 

 around contain the upper Lignitic formation, with remarkably thick 

 beds of combustible mineral. The coal is mined at Carbon Station by 

 a shaft descending through the following strata: 



1. Shale, cla}^ and sandstone at top, 35 feet. 



2. Ferruginous shale, with dicot3'ledonous leaves, 3 feet. 



3. Clay, shale, and sandstone, with plants at top, 18 feet. 



4. Coal (main), 9 feet. 



5. Fire-clay and shale, with dicotj'ledonous plants, 20 feet. 



6. Coal, 4 feet. 



7. Fire-clay and shale, 8 feet. 



8. Coal, 4 feet. 

 Total, 101 feet 



In following the railroad from Black Butte westward, the Lignitic 

 formation, already seen at the surface of the country from below Bitter 

 Creek Station, forms an irregularly broken ridge, whose general dip 

 toward the east is varied b}^ low undulations. In that way the meas- 

 ures slowly ascend to Point of Rocks, where they overlie the black 

 shale of the Fort Pierre Group, there constituting the axis of an an- 

 ticlinal, which is cut below Point of Pocks, b}^ the meanders of Bitter 

 creek. The counterface of the axis appears westward, in correspond- 

 ing strata, after passing Saltwell valle}^, and hence the dip to the 

 west brings to the surface the upper strata of the Lignitic at Rock 

 Spring, The section of the measures is perfectly clear and exposed 

 in its whole length. At Point of Rocks, and near the highest part of 

 the anticlinal axis, the Cretaceous strata are exposed 80 feet in thick- 

 ness, immediately and conformabl}^ overlaid by 185 feet of the Lig- 

 nitic sandstone, which, from its base, bears fucoidal remains. It has, 

 moreover, the composition and mode of disintegration of the same for- 

 mation at Raton, east of the station, 25 feet above the base of this 

 sandstone, there is a bed of coal 8 feet thick. Farther east, at Hall- 

 ville, a Lignitic bed, overlaid by shales where are imbedded a quantity 

 of fossil shells, is worked near the level of the A^alley at a short dis- 

 tance from the railroad. At Black Buttes a bed of lignite is worked, 

 too, above the sandstone. At Rock Spring, in boring for an artesian 



