REVIEW AND GENERAL DISCUSSION. 



495 





met here, one flowing westerly and the other one northwesterly. Moreover, the arrangement of 

 the metamorphic gravel in the great channel itself is such as I can explain only on the theory 

 of extensive accumulation followed by extensive excavation before the volcanic epoch. The crest 

 of the southeastern rim of this channel at Forest Hill is some 700 or 800 feet back in the hill 

 from the mouths of the tunnels ; and all over this rim the rock is smoothly water-worn, and there 

 is more or less auriferous gravel. But back, so far as the works have yet extended towards the 

 central and lowest portions of the channel, the stratum of metamorphic gravel is not very thick, 

 and the volcanic roof here descends far below the level of the southeastern rim. There are also 

 evidences of similar excavation of the previously accumulated gravel, and subsequent refilling with 

 volcanic matter at Yankee Jim's, the Dardanelles, and other points. But the most interesting 

 locality in this vicinity for the exhibition of a series of changes is perhaps the Paragon mine at 



Bath. 



It appears that at this locality* there was first accumulated a heavy mass of crushed and angular 

 fragments of the bed-rock which, by whatever means it was produced, cannot have travelled any 

 great distance, or have been exposed for any great length of time to the wearing action of running 

 water, though it does contain occasional water-worn and smoothly rounded pebbles. After this 

 came the accumulation of the great mass of smoothly water-worn gravel which underlies the " pay- 

 streak " or " lead " of the Paragon mine. Judging from the indications now visible at this locality 

 alone, it would be difficult, if not impossible, to say whether the stream which brought this mass 

 of gravel here came from the northwest or the southeast. But taking into consideration also the 

 facts at other localities, I am strongly inclined to think that it came from the southeast, in accord- 

 ance with the view above presented of the course of a river from Michigan Bluff to Bath and 



Forest Hill. 



When the great mass of this gravel had already accumulated, there came another change by 

 which the comparatively thin sheet of far richer gravel was spread a few feet thick with curious 

 uniformity over the broad surface of the older and poorer gravel. The question whence this pay- 

 streak came, presents some curious difficulties, as will be seen from a study of the notes relating to 

 it. But, all things considered, I think it probably came from the northeast, over the high bed-rock 



so near at hand in this direction. 



After this came the stream from up towards Weske's claim in the Michigan Bluff divide, cross- 

 ing Volcano Canon in the deep channel where the shaft is sunk near the upper road, following on 

 for a certain distance nearly parallel with the canon along its right bank, then passing more westerly 



into the ridge, cutting across the back end of the Paragon mine, excavating its channel to an 

 unknown breadth and depth through the pay-streak and the underlying gravel, and afterwards 

 refilling that channel with volcanic matter in the form of that called " gray cement " at Deadwood, 

 containing much semi-carbonized wood, etc. Thus at this locality there were no less than four 

 distinct and well-marked changes during the accumulation of the gravel itself. Next in order, and 

 overlying all previous accumulations, comes the gray, micaceous, volcanic sand (forming the roof 

 of the mine), whose thickness is so great and whose distribution so extensive in this ridge. Then 

 came another comparatively thin stratum of metamorphic gravel, and finally, over all, a great 

 thickness of the ordinary dark-colored volcanic ' cement,' filled with boulders of all sizes, which 

 forms the usual capping of the ridges here. 



From what has been already stated,+ it appears that at the New Jersey mine the southeastern 

 rim of the great channel is about 900 feet back in the hill, and that beyond this point the distance 

 already prospected on the slope of the rock going down into that channel is about 1,900 feet, and 

 that the lowest point here attained is about 157 feet below the level of the crest of the southeast 

 rim at that point. Yet the bottom of the channel has not yet been reached, and no one knows its 

 depth. It also appears that a little to the northeast of the New Jersey mine this rim-rock rises 

 much higher, in the form of a ridge, which extends some distance in that direction towards Bath. 

 Moreover, a large portion of the breasting and drifting in the tunnel mines at Forest Hill has been 



* See ante, p. 94. 



t See ante, pp. 94, 100, 





