LEADVILLE AND VICINITY. 205 



rising gently as it approached the continuation of the Mike fauh. The 

 o-round east of tliis fault having been lifted up, the Blue Limestone has 

 been in part removed by erosion and would next be found at the Long and 

 Derry mine, sloping again eastward as far as Union fault. Beyond this 

 fault it has again been removed by erosion, a little remnant only being 

 found above the White Porphyry in the uplifted portion adjoining the 

 Weston fault. Between this and the Mosquito fault is the arch of an anti- 

 clinal fold on which only Lower Quartzite is left. Beyond the Mosquito 

 fault erosion has cut down to the Archean rocks, the Blue Limestone being 

 next found on the western face of Mount Sheridan, along either of whose 

 sides it may be traced, sloping back to the crest of the main ridge. 



On the line of the section north of the first described (Section D, 

 Atlas Sheet VIII), which passes through Fryer and Yankee Hills, the 

 faulting action is less prominent, owing to the fact that many of the faults 

 have in their northern continuation merged into folds. On the north of 

 Leadville, extending from the western limit of the map to the eastern edge 

 of the town, is the same broad syncline noticed in the first section. From 

 here to the western edge, of Fryer Hill is a short anticline, from whose crest 

 the Blue Limestone has been planed oft'. It is succeeded by a shallow syn- 

 clinal fold under the western half of Fryer Hill, followed by a short anti- 

 cline at its crest, while in the gulch back or east of the hill is found the 

 rim of a deep synclinal basin which passes under Little Stray Horse Park. 

 At the west foot of Yankee Hill the ore-bearing horizon rises to the surface 

 and descends to the eastward again just beyond the summit of this hill, the 

 crest of the intervening anticlinal fold, into which the northern continua- 

 tion of the Iron fault merges, having been eroded ofi". From this point the 

 strata descend to the eastward, rising in a gentle wave near the Great Hope 

 mine, but not reaching the surface, and then sloping again eastward until 

 they rise on the South Evans anticline or are cut off' by Weston fault. 

 East of Weston fault, in the region around the mouth of South Evans 

 gulch, is another anticline or quaquaversal fold, whose summit has been worn 

 away, leaving the outcrops of succeeding beds in a series of concentric 

 rin<Ts. On the east of this fold the beds slope continuously to the eastward 



