258 GEOLOGY AISD MINING INDUSTRY OF LEADVILLE. 



the East Arkansas Valley. West of the summit of Prospect Mountain the 

 structure is that of a broad anticlinal and synclinal fold. On this line, by 

 a deeper erosi-^n at the head of the north fork of Little Evans, the body of 

 Mount Zion Porphyry has been exposed, to be covered again farther west 

 by portions of the Weber Shales and Weber Grits which have escaped 

 erosion on the top of Canterbury Hill, while at the foot of the steep slopes 

 in the valley of the east fork of the Arkansas the Blue Limestone comes to 

 the surface beneath the overlying Gray and White Porphyries. The Weber 

 Shales, which are brought to the surface by erosion, on the east side of 

 the Mount Zion Porphyry, are shown in the Esmeralda, Spotted Tail 

 (1-2), Little Maud (1-3), and Peru (1-5). The Thin Space (1-6) shaft 

 penetrated them to tlie underlying Mount Zion Porphjry, and the Texas 

 Ranger and Texas Boy's Chance, together with the intervening shafts, are 

 in the outcrop of Mount Zion Porphyry, which is traced as far west as 

 the Liberator. 



Southern slope. — Along the foot of the steep southern slope of the mountain 

 runs an anticlinal fold with an east-and-west axis, whose culminating point, 

 as shown in Section N, is at the forks of Little Evans gulch. Between this 

 and the top of the ridge is a shallow syncline, along whose axis a portion, 

 of the Weber Grits is left above the Weber Shales. The Gray Porphyry 

 underlying the Weber Shales on the west side of this syncline is developed 

 by the Brick Top, Bosco, Moose, and neighboring shafts. Towards the 

 north fork of Little Evans the Hecla and Mountain Lion shafts and the 

 Boettcher (Q-20) and adjoining (Q-19) tunnels are in the Weber Shales; 

 the Geneva Lake (Q-3), Mary Ella (Q-4), Katie Sullivan (Q-11), and 

 Buncombe (Q-13) in the underlying Gray Porphyry. 



On Canterbury Hill the Garland (Q-33), Little Willie (Q-49), and 

 adjoining shafts are also in the Weber Shales, on the south side of the syn- 

 cline ; likewise the Maryland, which develops the commencement of the 

 body of Mount Zion Porphyr)-, here only five feet in thickness The 

 Resumption (Q-60) shaft is in the Weber Grits, in the middle cf the syn- 

 cline. The Cardinal (Q-39) shaft finds a thin detaclied body of Weber 

 Shales between Gray smd White Porphyries 



