ON THE SHORES OF LAKE SUPERIOR. 



17 



but the space was filled with rubbish nearly to the surface. Further examination, 

 and cross trenching, disclosed the vein along a distance of three quarters of a mile, 

 iu places very broad, with a bearing coincident to that of the formation. 



It has now been worked to a denth of 250 feet, producing copper iii rich masses, 

 over a space twenty feet in thickness. In these wide places or pockets the i 

 miners enlarged their pits to correspond, and carried their works to greater depths. 

 Charcoal, broken maids, and ashes are mixed with the black earth and rocky frag- 

 ments of the pits. 



3d Group. 



Minnesota Mine. — As I have before stated, it was upon this location that the exist- 

 ence of mines, long since wrought, on Lake Superior was first made known to us. 

 It is here, also, that the most extensive and interesting works of that kind are to be 

 found. 



The Minnesota lodes have a direction like those at Portage Lake, and different 

 from those at Toint Keweenaw. The veins about the forks of the Ontonagon, 

 embracing a district of forty-five miles in* length, on the mineral range, from the 

 Douglass Houghton Mine, on the east, to the Akogebe Lake, on the west, run tcith 

 the range, and not across it. Their bearing is, therefore, north-easterly and south- 

 westerly, or about N. 54° East. 



Fig. 9. 



Minnesota Mine. Section across the Vein, looking from the easterly quarter. N. 30° W.—BB. Mineral vein 

 dipping north.— J .1. Wall rock of compact trap.— a. ". Left standing a part of the original surface support 

 to the hanging wall.— m. Mass of copper sustained by timbers. — b. Ancient burrow or spoil bank.— c c. Vein 

 matter embracing masses of copper n n. 



On the Minnesota there is a group of veins nearly parallel among themselves, 

 tour in number, and on all these the ancients labored. The surface presents a cor- 



