N. W. Portion of Lake Huron. 255 
- .Of the Grand Manitou, which now succeeds, little is 
known. Its western termination is remarkable for its ma- 
jestic precipices. 
he northern mainland is high, barren and rocky; the 
southern shore, being of a secondary formation, is level, and 
abounding in marshes and the densest woods. 
ts, the northern being rocky and of variable ele- 
vation; and the southern more wid i in its level, and 
generally lower: in its present form, the bed of the Hu- 
ron Lake is covered with the debris of distant countries: 
its rocks are furrowed and abraded ; its loftiest heights over- 
thrown, (of greenstone, one of the most tenacious of miner- 
als, as in the narrows of St. Joseph) separating large tracts 
from the Main; and finally, passages from ten to twelve 
miles wide and ten long, are forced in the Great Manitou- 
line barrier itself. These violences,-and particularly the 
first and last, indicate a more general and powerful agency 
than that of a gradual accumulation of the waters of Lakes 
Huron and Superior, whose united surplus requires only an 
outlet of three hundred yards in breadth (R. St. Clair) in 
place of the four Manitouline Detours. The effect of a 
gradual accumulation of water would have been to have fil- 
led the north division of Lake Huron, and in the end, to 
the ruins of annihilated mountains. 
