3(54 GEOLOGIC OF THE DENVER BASIN. 



the examination by the Survey, L890. Changes have occurred with the 

 advent of Other owners, and so far as possible all later names are added in 

 brackets. 



Superior district. — Superior mine (abandoned). 



Louisville district. — 'The Welch (abandoned), Marshall Consolidated, 

 Marshall Slope, Caledonia, Anne, Aja\ [Leader], Hecla Nos. 1 and 2. 



Lafayette district. — The Cannon [Colorado Smokeless], Simpson Nos. 

 1 and •_', Spencer, Excelsior, Gladstone, Ottis. 



Mitchell district. — The Mitchell, New Mitchell, Cleveland, McGregor, 

 Stewart, Garfield Nos. 1 and ■_', Longs Peak, Boulder Valley (abandoned), 

 Northwestern. 



Canfield-Erie district. — The Jackson [Chase], Star, Progress [Stand- 

 ard], Northrup (closed). New Boulder Valley, Superior (abandoned), Deitz 

 (abandoned), Briggs (abandoned), 



til 1 : 81 PERIOK D1STRII l. 



This includes the portion of the field lying on the northwestern rim 

 of the Coal ('reek syncline, separated from the main body of coal to the 

 east li\ the Harper and Sand Gulch faults. 



The confines of the coal and the general geology were given in defining 

 thi' svncline's rim. A single opening of importance, the Superior shaft, is 

 located on the northern slopes of the Davidson mesa, a seam ."> feet <i inches 

 thick being reported as cut at a depth of !><) feet. The coal is said to be 

 clear and hard. The mine has long been abandoned. 



I'll K LOUISVILL1 I'M RIC I ■ 



The structural limits of the Louisville district are the Louisville fault 

 on the southeast and the rim of the syncline and the Harper fault on the 

 northwest; southwest, also, it extends to the rim, while to the northeast it 

 merges with the Lafayette area. That the entire district is underlain with 

 coal of workable thickness is doubtful, hut the distribution of the mines 

 and prospects indicates that a large portion of it may become productive. 

 The region varies widely, however, in the value of its lands for coal- 

 mining purposes, lor beneath a part certain of the beds are thick and 

 consolidated, while beneath the remainder the) are thin, separated, and 



