24 TIIK FENOKEE IKON-IJEAKING HEHIES. 



Above the ore, tli;it is nortb of it, the slate has been hardened, probably by some 

 volcanic agency, into a conipuct mass, bnt still showing traces of its original laminated 

 strnctnre. This higlily iiidiiratcil rock is the nuclcns of the ridge, nsnally forming 

 the crest or highest part: :ind it forms llie nortli slope, excejjt where covered with the 

 bowlders and other coarse materials of the' Drift formation. If we may judge from 

 the polished and grooved surfaces, we may snjipose that this excessively hard rock 

 has resisted the action of tlie jiowerfnl currents and icel)ergs that once flowed over the 

 very top of the ridge, which, witii its iu\alnable beds of iron ore, was thus saved from 

 destruction. 



All the rocks, including the ore, have a considerable dij) toward the north, or 

 toward the great basin of hike Superior; and they are always found in the same 

 relative position in regard to the ore. If we, at any new locality, could find either of 

 the rocks in place, we at once knew which way to turn to find the ore. 



The magnetic ore of the Pcin)kee Iron range contains a notable and much varying 

 proportion of silica in its composition, but is free from sulphur and other deleterious 

 qualities, corresponding in this respect witli most of the iron ores of this remote 

 geological epoch. It is in some localities so highly, magnetic that particles adhere to 

 the hammer when struck, like iron tilings to a magnet; and the compass needle as 

 often iiointed toward the e;ist or west as to the north, in one instance being entirely 

 reversed, the north end pointing to the south. At Penokee, where Bad river crosses 

 the range, the ore exists in such abundance that it may be obtained from the face of 

 the hill, much as stone is taken from an ordinary stone ipiarry. Large masses 

 that have fallen from the dills now lie loose upon the surface, and will supply a fur- 

 nace for many years before it will be necessary to resort to the original bed (pp. 

 394-396). 



18GO. 



Lapham (I. A.). Report to the Directors of the Wisconsin and Lake Superior 

 Mining and Smelting Company, in the Penokee Iron Range of Lake Superior, with 

 Rejiorts and Statistics, showing its Mineral Wealth and Prospects, Charter and 

 Organization of the Wisconsin and Lake Superior Mining and Smelting Company, 

 Milwaukee, 1800, pp. 22-37. 



Tliis is a |)rivate economic report leased on tlie same explorati<ni as the 

 paper imnnediately preceding. It contains, however, some fmlher general- 

 izations of interest. Dr. T^ajiliam's investigations appear to have been con- 

 fined ahnost entirely to the ferruginous belt ai^d its immediately adjacent 

 layers, which i'orm the Penokee ridge proper. The higher members of the 

 series received only very slight twnd incidental attention. The following 

 quotation gives the more important generalizations reached; 



