071 the Lake Superior Land District 227 



Isle Royale is the counterpart of Keweenaw Point ; but al- 

 though the Jesuits formed the most extravagant notions of its 

 mineral wealth, nothing has lately been revealed to justify those 

 expectations ; at least, it is vastly inferior to Keweenaw Point or 

 the vicinity of the Ontonagon as a mining region. Bloreover the 

 soil is scanty and the timber dwarfed and stunted. 



" The shores are lined with dense but dwarfed forests of cedar 

 and spruce, with their branches interlocking and wreathed with 

 long and drooping festoons of moss. While the tops of the trees 

 flourish luxuriantly, the lower branches die off and stand out as 

 so many spikes, to oppose the progress of the explorer. So dense 

 IS the interwoven ma?s of foliage that the noonday sunlight 

 hardly penetrates it. The air is stifled; and at every step the 

 explorer starts up swarms of musquitoes, which, the very instant 

 he pauses, assail him. Bad as this region is by nature, man has 

 rendered it still worse. Fires have swept over large tracts, con- 

 suming the leaves and twigs and destroying the growth, while 

 the heavy winds have prostrated the half-charred trunks, and 

 piled them up so as to form almost impenetrable barriers. 

 ^ As we ascend the ridges, the maple and birch replace the 



cedar and the spruce, and the physical obstructions become less 

 formidable- These, ridges occur at short intervals, and preserve 

 a great degree of parallelism — bearing northwest and southeast; 

 they are uniformly precipitous on the north, and gently sloping on 

 the south. The valleys between are occupied by swamps, clothed 

 with a dense growth of resinous trees, or with small lakes ar- 

 ranged in chains. The coast of the island is rock bound, and, 

 like Iceland, intersected by unmexons fiords ^ or narrow and deeply 

 indented bays." 



Trappean rocks form numerous ridges, seldom reaching 500 

 feet in height and running from N.E. to S.W. They are at times 

 in regular columns; and also pass into amygdaloid and varioloid 

 trap. In numerous places they form distinctly a series of beds 

 which are conformable with the detrital rocks. The intercala- 

 tions of sandstone and trap* are well seen at Chippewa Harbor, 

 there being no less than five in less than a mile. 



" These beds bear S.W. and N.E., and dip from 12^ to 20^ to 

 the S.E., and respectively vary from a foot to eighty feet in thick- 

 ness. When traced across the harbor a (ew rods only in extent, 

 they are found to have been subjected to a powerful dislocation, 

 extending in a N.W. and S.E. course, and amounting to 971 feet 

 ^n a linear direction. 



At and near the junctions of these different rocks, marked 

 changes in their lithological characters are observed, which throw 

 »iuch light on their origin. 



d-i 



♦ 



Many facts of this nature are mentioned in Dr. Jackson's Report, page 472. 



