COMPARISON WITH SIMILAR ORE DEPOSITS ELSEWHERE. 



277 



followed downward over a thousand feet, yet the local irregularity of the outline 

 is like that of the typical bonanza. At Tonopah a similar shoot-like form with 

 a definite pitch has been discerned, but the developments thus far made do not 



(B) 



FIG. 78. Vertical cross sections showing forms of ore bodies or bonanzas in districts similar to Tonopah. (A ) Vertical section 

 of Poor Man and Silver Cord veins, showing extent of rich ore body in De Lamar district; after Lindgren, Twentieth 

 Ann. Kept. U. S. Geol. Survey, pt. 3, p. 152. (B) Portion of projected vertical section of the Comstock lode, Nevada, 

 showing some of the chief bonanzas on the vein; adapted from Becker, Men. U. S. Geol. Survey, vol. 3, atlas. 

 (O Projected vertical section of a portion of the Cristo vein, Pachuca, Mexico, showing bonanzas on the vein: after 

 Aguilera and Ordonez, Boletin del Instituto geo!6gico de Mexico, Nos. 7, 8, and 9. 



show so great a persistency as at De Lamar. At Tonopah the connection of the 

 shoots with cross fractures is evident, and the localization of the ore deposition 

 at intersections of especially fractured zones seems the correct explanation. It 



