O F T H E 8 O U T H S H ORE O F L A K E S U P E K I 0 R. 



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SECTION V. 



DETAILED SECTIONS. 



Montreal River. — The best exposure of the contact of the trap and sedimentary 

 rocks in the bed of the Montreal River, is on the Michigan side. Here, about three 

 miles from the mouth, the " Cypress River Company" erected houses, and com- 

 menced operations for copper in 1846, and carefully measured the thickness of the 

 slate and conglomerate beds. The latter is not uniform in thickness, owing to 

 the disturbance of the invading trap. It measures eighteen hundred feet below the 

 second leap of the falls at the Montreal trail. The channel of the river is sunk 

 from one hundred and twenty to one hundred and eighty feet in the sand-rock, and 

 is, for several miles from the mouth, very crooked. Its sides are steep, frequently 

 perpendicular, and its width is often little more than its depth. The explorer can 

 pass along it only in low water, by wading. The first fall is at the mouth of the 

 river, fifty-six feet, in two cascades, over the tilted edges of the sand-rock. 



The second fall is at the crossing of the Montreal trail, five or six miles by the 

 tortuous channel, but not quite three miles by the trail. 



The bearing of the strata here is not regular, but is about northeast by north, 

 the dip northwest by west, 70°, 75°, 80° to 85°. The thickness of the black slate- 

 beds, including shaly sandstone, is seven hundred and fifty feet, reckoning from the 

 conglomerate to the clear sandstone. The sandstone which is seen between the 

 beds, b, b, b, of black slate, has an apparent horizontal lamination, nearly at right 

 angles to the dip of the slate-beds ; but this is no doubt due to jointage, and not to 

 stratification. Several hundred feet lower down the river than is shown in the 

 section, is a band of well-defined conglomerate, one hundred feet thick, passing 

 through the sandstone, with the same dip. At the junction of c and t, there is 

 great confusion ; protruding, mixed, and broken masses of trap, conglomerate, and 

 sandstone, are seen, giving irresistible evidences of the former presence of mighty 

 forces. 



The section on the Montreal River, showing the junction of the sedimentary 

 strata and trap, is shown in the following section. 



Sec. l.—s, s, s. Red sandstone, b, b, b. Bands of black slate, in sandstone, r. Conglomerate, eighteen hundred feet thick, t. Dark-coloured 

 trap, "with metallic veins. 



Sec. 2— a, a, a. Hard, thin bands of sandstone, s, s, s. Soft, red, shaly sandstone. 



The conglomerate is filled with veins and spots of calcareous spar ; and the trap 

 has many irregular, crooked, and limited fissures or veins, containing copper, spar, 

 phrenite, quartz, and the usual materials of trap-veins. It was upon these indica- 

 tions that the Cypress River Mining Company made an energetic beginning, but 

 has since abandoned the location. 



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