444 



MAGNETIC IRON-BEDS 



sponding fall, of thirty-two feet, over the trap-rocks. In ascending the gorge from 

 the junction to the latter falls, we rise thirty-seven feet along a deep channel, in 

 places thirty feet wide and seventy feet deep, its walls composed of a mixture of 

 red breccia and red trap, in various states of hardness and of change. These falls 

 present striking, rude, and picturesque views. 



On the east branch, the trap-rock is very changeable, lying in apparent overflows, 

 of limited thickness, where red trap, amygdaloid greenstone, and quartzose, gray, 

 and compact black trap, are seen alternately, dipping at high angles southerly and 

 easterly. Here, as in the two preceding sections, there appears to be no sufficient 

 evidence of regular veins, and consequently of valuable mineral. The sandstone, 

 s, is a repetition of the ordinary red and variegated sand-rock of Lake Superior, 

 standing on edge, as at the mouth of Montreal River. The conglomerate bed, c, 

 is conformable to s, or nearly so; its strike, south and by west; its dip west and by 

 north 85°, 87°, and 90° ; it graduates into the red trap-bed ; so that it is not always 

 easy to decide to which division the rock belongs. The conglomerate, as usual near 

 the trap, has spots and seams of pure calcareous spar, extracted by the volcanic fires 

 to which it has been subject. The slaty beds of sandstone near the conglomerate 

 have disappeared ; and not far west of this point, the trap itself is thought to be 

 hidden under the red clay and drift. 



The specimens of the collections on the South Shore of Lake Superior, Nos. 60 

 to 66, inclusive, represent the formations about the Falls of Tyler's Fork. 



SECTION VI. 



MAGNETIC-IRON BEDS OE THE PENOKIE RANGE. 



The most easterly appearance of magnetic iron which I observed was in fissile 

 black slate, about four miles west of the Montreal Trail, along which the Section 

 No. 4, W, is made. The bed lies back of the trappose range, about sixteen miles 

 from the Lake, in a protrusion of metamorphic slates, the argillaceous portions merely 

 tinged with iron. About four miles along the strike of the beds, southwest by 

 west, the bed was seen by Mr. Randall, in 1848, in the Fourth Principal Meridian 

 in Township 44° north, eighteen miles from the Lake. From thence I and my 

 assistant, Mr. Beesly, an active woodsman, and faithful and acute observer, traced 

 it at moderate intervals, along the uplift, to the west end of " Lac des Anglais," or 

 about fifteen miles, to where the range terminates. 1 " Here the metamorphic slates, 

 that first show themselves between the Montreal River and the Montreal Trail, on 

 the east, sink beneath the level of the country, and are replaced by syenitic rocks. 



By examining the Sections Nos. 1, 2, 3, and 4, W, attached to this Report, the 

 position of the iron-bearing rocks will be found to be the same in each ; and the 

 details of the rocky beds above and below the iron are also the same, so that we 



• : There being but one surveyed line in the Bad River country, the distances are of course by approxi- 

 mate estimation. 



