APPENDIX. 



Since the first part of this work was put in type, another report on 



the geology of Keweenaw Point has been pubHshed by Professor Irving, 



in the Third Annual Eeport of the Director of the United States 



Geological Survey. The state of our knowledge up to the time of the 



casting of that portion of the work has been presented on pages 76-157, 



482-492. In Irving's report the before-mentioned observations {ante, 



pp. 115, 116, 482-484) of Wadaworth at the Douglass Houghton Falls 



are accepted and pronounced correct in every particular but one. 



Irving then acknowledges that the copper-bearing rocks are continnous 



with the eastern sandstone beloAv the falls ; but in order to escape the 



dilemma in which this places him, he says that below on the stream is 



a covered space between the true eastern sandstones and those which 



every previous observer had called such, and that here is the junction 



between the sandstone and Kuweenawan scries. This space he said 



Wadsworlh had bridged over in his imagination. To tliis the latter 



replied, "that, by digging in the stream and on the banks of the 



ravine, he had actually traced (not imagined) the relations of these 



rocks, going from those dipping five degrees up to those dipping 



twenty-five degrees, and that they were seen to form a continnous 



super-imposed scries, no such cliff as imagined [by Irving] existing 

 between them." * 



Irving fnrther claimed that at the junction of the sandstone and 

 traps on the Hungarian River {ante, pp. 113-115) the sandstone was a 

 loose piece, or, if not, the basaltic rock surely was, and that the prevail- 

 ing dip of the sandstone was to the southeast. To this '' ^yadsworth 

 replied that the dips given in the report [Irving's] appeared to havo 

 been taken from the frost-dislocated rock on the sides of tlie stream, 

 while his [Wadsworth^s] were taken in the bed of the stream, when the 



* Science, 1884, HI. 563. 



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