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 Report 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 Wadsworth at the Douglass Houghton Falls 

 are accepted and pronounced correct in every particular but one. 

 Irving then acknowledges that the copper-bearing rocks are continuous 

 with the eastern sandstone below 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 tlie sandstone and Keweenawan series. This space he said 

 "Wadsworth had bridged over in his imagination. To this 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 continuous 

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

 between them." * 



Irving further 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 " Wadsworth 

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

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

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



• Science, 1884, III. 553. 



