318 APPENDIX. 



Ekratic Block Group. — Wherever, in fact, the geologist sets 

 his foot, on the shores of the upper lakes, he finds himself on the 

 great drift stratum, and cannot but revert to that era when waters, 

 on a grander scale, swept over these plains, and the lakes played 

 rampantly over wider areas.* 



Basin of Lake Superior. — We entered this island sea as if 

 by a kind of geological gate, in which the sandstone cliffs of Point 

 Iroquois, on the one hand, stand opposite to the granitical hills 

 of Gross Cape on the other. 



In order to conceive of its geology, it may subserve the pur- 

 poses of description to compare it to a vast basonic crater. The 

 rim of this crater has been estimated, by Sir Alexander Mackenzie, 

 at fifteen hundred miles. The primitive formations of Labrador 

 and Hudson's Bay coasts come up, so as to form the eastern and 

 northern sides of the rim, around which they stand in cliffs of 

 sienitic greenstone and hornblendic rocks, in some places a thou- 

 sand feet high. On its south and southwest shores, this formation 

 of the elder class of rocks forms also a considerable portion of the 

 coast; as in the rough tract of Granite Point, the Porcupine and 

 Iron River Mountains, and the primitive tract west of Chegoime- 

 gon, or Lapointe. It will serve to denote the broken character 

 of this rim, if we state that the entire plain of the lake, running 

 against and fitting to this rim, was originally filled up with the 

 red, gray, and mottled sandstone, which gave way and fell in at 

 localities west of the great Keweena Peninsula, converting its 

 bottom into an anteclinal axis. 



Volcanic action, to which this disturbance in its westerly 



/ 



* During a subsequent residence of eleven years at this point, the excavations 

 made on both sides of the river, in digging wells, canals made by the military, &c., 

 fully demonstrated the truth of this general observation. In these positions, it was 

 evident that some greatly superior force of watery removal, such as does not now 

 exist, had heaped together particles of similar matters, according to laws which 

 govern moving, compacted masses of water, leaving clay to settle according to the 

 laws of diffused clay, sand of sand, and pebbles and boulders of pebbles and 

 boulders. In their change and redeposit, gravity has evidently been the primary 

 cause, modified by compressed currents, attraction, and probably those secret and 

 still undeveloped magnetic and electric influences which exist in connection with 

 astronomical phenomena. That the earth's surface, "standing out of the water and 

 in the water," has been disrupted and preyed upon by oceanic power, no one, at 

 this day of geological illumination, will deny. 



