OEE DEPOSITS OF UPPEE HURONIAX. 



179 



Columbia, Dunn, Mastodon, and others to the west (PI. XVIII), are prob- 

 ably the western continuation of this line of mines, and folloAv the trend of 

 the main synclinal axis of the district. The position of these mines with 

 reference to the main structural features of the district can be seen on the 

 relief map and the sketch map corresponding to it, PI. XIV. 



The section made through the closely folded Upper Huronian beds by 



Fig. 12. — Sketch illustratiug contortion of Upper Hiironiau strata. 



the Paint RiA^er affords the best opportunity in the district for studying the 

 rocks, but the rocks are so crumpled that even here the succession waS not 

 made out with certainty. 



The sketch fig. 12, by W. N. Merriam,^ shows the folding of the slate and 

 chert strata as seen in the railroad cut between the Paint River and the Lin- 

 coln mine. The strike of the rocks is about N. 80° E. The sketch is taken 

 looking almost along the strike 



of the beds. In fig. 13 a sec- ...- — \ 



ond sketch is given, also by 

 W. N. Merriam, which illus- 

 trates the rapid change in strike 

 in these beds, due to the con- 

 tortion of the strata. This 

 change is seen near the east 

 end of the wagon bridge just 

 across the Paint River from 

 Crystal Falls. At this point 

 the beds bend from a strike ot 

 S. 40° E. to W. 10° S. The change takes place by means of three very 

 sharp bends. 



The following are the observations made by Rominger upon these expo- 

 sures near Crystal Falls: 



Among the recently discovered productive fields for iron mining, the vicinity of 

 Crystal Falls lias become famous for its wealth in ore. The formation enclosing the ore 



-Sketch showing change of strike of Upper Huroni; 

 due to the folds. 



' Manuscript notes. 



