of Lake Superior. 265 



and in depositing beds of clay, sand, ^c, has existed in the cur- 

 rent, supposed by Mr. Hayden* and Professor Buckland, to have 

 traversed North America from the N.E. The shores of the 

 St. Lawrence, and its lakes afford further evidence in favour of 

 this hypothesis in the removal of enormous rock masses from their 

 known depositaries (contrary to the present current of the rivers), 

 from N.E. to the S.E., or nearly. Large fragments of the trap 

 rock of Montreal mountain, remarkable in itself, and abounding 

 in crystals of augite, zeolite, and hornblende, are found one 

 hundred and ten miles on the S.E., up the St. Lawrence, and 

 on the south around the head of Lake Champlain. Vast 

 blocks of the ophicalcic rocks of Grenville on the Ottawa 

 River, are found, on the S.W., near York, on the west of Lake 

 Ontario. The crystalline white marble of the higher parts of 

 the Ottawa is distributed in great quantities over the shores 

 of Lakes Ontario and Simcoe. The numerous bowlders of the 

 portage of St. Mary have been traced to Lake Huron and 

 the N.E, coast of Lake Superior. The calcedonies and agate, 

 of the north shores of Lake Superior and Point Keewawoonan 

 have travelled as far S.W. as Lake Pepin, an expansion of 

 the Mississippi (Schoolcraft). Much of the south shore of the 

 former lake is covered with the debris of the amygdaloid of the 

 north. The large rolled mass of copper, lying under a high gravelly 

 bank from thirty-six to forty miles up the Ontonagon, is almost 

 surely from Keewawoonan on the N.E. The south and west 

 shores of the Lake of the Woods t, are loaded with sand and 

 bowlders, while the northern and east shores are comparatively 

 destitute of them. The bowlders are sometimes of immense size 

 and angular. They are granites, greenstones, greenstone pudding- 

 stone, and limestone ; the two first only being now and then 

 referrible to their original situation on the north shore. The lime- 



* In an original and valuable work, entitled Geological Essays ; published 

 in 1R20, at Baltitnorc. 



t Not the Lake of the Woods, mentioned by Captain Franklin, U.N. ; but 

 the lake in north latitude 4'J°. and west long. 49°. 30'. and 45U~500 miles in 

 eircumlcrence. 



Vol. XVIIL T 



