LEADVILLE AND VICINITY. 203 



southern edge of the map, the Iowa gulch cross-fault, which connects the 

 Weston and Ball Mountain faults ; 2, the Union cross-fault, which extends 

 from the head of Union gulch across upper Long and Deny Hill and joins 

 Weston fault in the bed of Iowa gulch ; 3, the Colorado Prince fault, north 

 of Breece Hill, a diagonal cross-fault approximately parallel to South Evans 

 gulch, which connects Ball Mountain and Weston faults ; 4, on the west 

 slope of Breece Hill another cross-fault, the Breece fault, running nearly east 

 and west, joining the northern end of Mike fault with Weston fault; 5, a little 

 farther west the Adelaide cross-fault, which connects Iron and Mike faults; 

 6, at California gulch the southern continuation of Iron fault is formed by 

 three different faults : Dome fault, connected with Iron fault by the Califor- 

 nia cross-fault, following the line of the gulch, and Emmett fault, which 

 connects California fault with Iron fault. Pilot fault, already mentioned, is 

 a short north and south fault, crossing California gulch above Mike fault, 

 running across the west end of Printer Boy Hill, and joining Mike fault in 

 Iowa gulch. The Pendery fault, already mentioned, and the South Dyer 

 fault, a cross-fault running eastward from the Mosquito fault along the south 

 slopes of Dyer Mountain, raise to seventeen the total number of faults rep- 

 resented on the map. 



In ground broken by such a complicated network of fractures and 

 subjected since to the enormous erosion which is shown to have taken place 

 in this region, it is extremely difficult even for a trained geologist to recon- 

 struct ideally the original folds into which the sedimentary beds and their 

 included sheets of porphyry were once compressed. As, however, the ac- 

 tion of faulting was so intimately connected with that of folding and the 

 displacements in many cases pass into simple folds, it is essential, in order 

 to obtain a clear idea of the relative position of the different beds below 

 the surface and the depths at which they may be found, that one should be 

 able to reconstruct in his mind the original folds, and then figure to himself 

 the faulting action which has brought the beds into the discordant juxta- 

 position in which they are now found on the surface, as shown on the map. 

 For this purpose the general structure along certain east and west lines 

 will be first described, and after that the present condition of the surface 

 and the underground structure, as revealed by shafts in each zone or 



