coal. 357 



The coal to the south of th<j Erie fracture probably remains at nearly 

 its normal depth beneath the surface until within the influence of the sharp 

 flexure immediately west of the main Coal Creek fault, where it then rises 

 to the surface, resumes its southward trend, crosses Coal ('reek at the point 

 indicated on the map, and is found in outcrop in the valley, on the west 



side of Coal ("reek, east of the Mitchell mine. 



The point next south of the Mitchell group of mines at which the coal 

 is definitely located is a few hundred yards wot of the trestle by which 

 the old Denver, Utah and Pacific Railroad crosses Coal ('reek. Com] .'! 

 feet 1<> inches thick is here reported at the bottom of a shaft 93 feet deep. 

 The dip is 11 NW., approximately at right angles to the trend of the 

 Coal ('reek fault. On this dip the coal would reach the surface about odd 

 feet east of the shaft, a deduction witli which surface observations coincide. 

 A short distance south the displacement along the fracture apparently 

 begins to diminish, and the coal sinks and gradually approaches that on 

 the opposite or southeast side of the fault. 



Opposite Louisville tlie southeastern rim of the syncline is again locally 

 affected, here by the Louisville fault, This passes from the periphery of 

 the genera] syncline diagonally across its trough beneath the vallej of 

 upper Coal Creek, separating it into the Lafayette and Louisville subbasins. 

 The trend of the fault is approximately X. 45 " J E., the downthrow to the 

 southeast, the maximum displacement at least 200 feet, and perhaps 

 considerably greater. 



The fault appears in the railroad cut in the southern bluffs of the valley 

 just south of Louisville (fig. 9, }». 12.")), where the beds opposed are the 

 lower members of the upper Laramie and sandstone 1», or the top of A in 

 the lower division. The succession of the strata northwest of the fracture 



is rapid, the dip being about 45° NW. The Fox Hills probably occupies 

 a narrow belt beneath the Quaternary wash at the foot of the bluffs; then 

 follow the several members of the Laramie in order. The linear extent of 

 the fault is unknown. No trace of it appears in the bluffs north of the 

 valley, and it is here probably completely reduced. The points at which 

 the horizon of the coal reaches the surface on the west of the fault are 

 unknown, but southeast of the Welsh mine at Louisville the outcrop is 



