ANCIENT COPPER-MINES OF ISLE ROY ALE. 605 



made by an unskilled hand, and was unjBnished. This allies these min- 

 ers with those of the south shore of the lake. The absence of these 

 hard, rounded stones on the shores of the south side of Lake Superior,* 

 owing to the strike of the formation producing them across the interior 

 of the States of Michigan and Wisconsin, made it necessary for the 

 miners on that side to manufacture their hammers, which they did 

 with greater perfection and symmetry than are seen in the beach- 

 wrought hammers of the Isle Roy ale miners ; and they almost inva- 

 riably grooved them for a withe. Those found on Isle Royale are 

 generally broken with use on one end or on both, a fact which proba- 

 bly caused their abandonment. Fig. 5 shows the imperfectly grooved 



Fig. 5. Imperfectly 'withed Hammer, from the Ancient Mines of Isle Royale. 



hammer belonging to Dr. Gailey. Fig. 6 shows the outline and irreg- 

 ularity of three others, also found at the Minong mine. These are a 

 fair average for form, of the most of those found. They are also 

 evidently such as would result from the constant attrition of angular 

 fragments on the beach, and show no evidence of designed shaping. 



Fig. 6. Stone Hammers from the Ancient Mines of Isle Royale. 



Their battered and even fractured extremities are the only sign of the 

 agency of man in giving them shape. 



If we inquire now who were the men, and when did they live, who 

 did this work, we enter on a very interesting question, but one on 

 which we are not in total darkness. A single observation at the pits 

 at once places them later than the last glacial epoch. The dirt that 



* Ship-loads of these stones are transported from the north shore of Lake Superior 

 for paving streets in Chicago and other cities. 



