ON LAKE SUPERIOR. 231 



the veins. It was these masses of solid copper which the 

 native North Americans were in the habit of extracting. 

 Their workings are scattered at intervals over the whole 

 copper region, for a hundred miles, and are sunk twelve 

 or fifteen feet deep. Their working hammers are made 

 of a hard variety of trap — as many as fifty cartloads of 

 them might be collected at the Minnesota mine, near 

 the Ontonagon River ! In one of the abandoned pits of 

 this mine, at the depth of twelve feet, a mass of native 

 copper weighing above five tons was found, which had 

 been worked round on all sides, cleared from the rock, 

 and partly raised, by the ancient native miners, and is 

 supposed to have been abandoned because of its great 

 size. Some have imagined that these mining operations 

 must have been conducted by a former race of inhabi- 

 tants, possessed of more skill than those who were found 

 in the country on the arrival of the Europeans. That 

 the excavations are ancient is proved by the fact that the 

 workings are filled up, and that over them are growing 

 trees which are upwards of a hundred years old. But 

 Dr Charles Jackson states that, with the hammer, toma- 

 hawks and scalping-knives have been found ; and he 

 conjectures that, as the Indians had no use for the cop- 

 per but for the manufacture of implements, they had 

 abandoned the mines soon after 1640, when the early 

 missions of the French Jesuits put them in the way of 

 procuring implements of more valuable steel. The 

 succeeding interval of two hundred years would account 

 for all the appearances of antiquity which have as yet 

 been observed. 



The Kewenaw Point consists of a series of parallel 

 ridges of trap, which have an E.N.E. direction. The 

 trap contains much iron, and, where it comes in contact 

 with sandstone, assumes the characters of an amygda- 

 loid. In this amygdaloid the veins are rich in metallic 

 copper. In the superincumbent trap they are pinched 



