COPPER MINES. 203 



several porcupines had fixed their quarters for hybernation ; 

 but detecting evidences of artificial excavation, he proceeded 

 to clear out the accumulated soil, and not only exposed to 

 view a vein of copper, but found in the rubbish numerous 

 stone mauls and hammers of the ancient workmen. Sub- 

 sequent observations brought to light ancient excavations of 

 great extent, frequently from twenty-five to thirty feet deep, 

 and scattered over an area of several miles. The rubbish 

 taken from these is piled up in mounds alongside ; while the 

 trenches have been gradually refilled with the soil and decay- 

 ing vegetable-matter gathered through the long centuries 

 since their desertion ; and over all, the giants of the forest 

 have grown, and withered, and fallen to decay. Mr. Knapp, 

 the agent of the Minnesota Mining Company, counted three 

 hundred and ninety-five annular rings on a hemlock-tree, 

 which grew on one of the mounds of earth thrown out of an 

 ancient mine. Mr. Foster also notes the great size and age 

 of a pine stump, which must have grown, flourished and died 

 since the works were deserted ; and Mr. C. Whittesley not 

 only refers to living trees now flourishing in the gathered 

 soil of the abandoned trenches, upwards of three hundred 

 years old, but adds, ' On the same spot there are the de- 

 cayed trunks of a preceding generation or generations of 

 trees that have arrived at maturity, and fallen down from old 

 age/ According to the same writer, in a communication 

 made to the American Association, at the Montreal meeting 

 in 1857, these ancient works extend over a track from 100 

 to 150 miles in length, along the southern shore of the 

 lake/' 



In another excavation was found a detached mass of native 

 copper, weighing upwards of six tons. It rested on an 

 artificial cradle of black oak, partly preserved by immersion 

 in water. Various implements and tools of the same metal 

 were found with it. The commonest of these are the stone 



