186 Dr. BiGSBY on the Geography and Geology of Lake Huron. 



Thunder Bay Islands and Middle Islands are flat, calcareous, and well 

 wooded. The lake, as I am informed by Major Delafield, for three quarters 

 of a mile east of Middle Island has only four feet water; indeed all the se- 

 condary islands of Lake Huron are surrounded by extensive spits and shal- 

 lows. 



The shore from Point aux Barques to the river St. Clair forms a tolerably 

 straight line of beach with now and then a low cliff of clay. About midway, 

 a large block of white limestone rises from the waters of the lake, well known 

 to voyageurs by the name of Rocheblanche. 



In describing- the Manitouline Isles, I have already noticed Cabot's Head, 

 and the coast in its vicinity. 



I have collected very few materials for the geography of the Georgian Bay. 

 It is now under survey by Lieut. Bayfield R.N., assisted by Midsh. Collins. 

 They report it to be crowded with islands and rocks. 



Penetanguishene*, the British naval station in Lake Huron, is situated in an 

 inner bay of Gloucester Harbour. It is sheltered, as its name indicates, by 

 hifls of sand and rolled blocks ; the coast and neighbouring islands being of 

 similar constitution for 30 miles round, but having a primitive base. 



It remains now to add a few remarks on the rivers of Lake Huron. 



The principal rivers are the Thessalon, Missassaga, French, Severn, St. 

 Clair, and Saguinaf . There are multitudes of smaller streams unmarked in 

 the map, which pour a brownish red water into the lake, and several of consi- 

 derable size to the east-south-east of Cabot's Head. 



The river Thessalon flows into a deep bay on the north coast. It is 50 yards 

 wide at its mouth ; and in three or four miles becomes a mere creek. I have 

 noticed it because it is usually thought larger. 



The river Missassaga at its entrance into the lake is ^ a mile wide, and 

 passes through a large swampy country, apparently afluvial. For five or six 

 miles the breadth rather increases as we proceed upwards. The current, 

 though usually sluggish, is at times rapid. Its borders are covered with long 

 grass and willows. Indians say that its source is a lake of the same name, 

 lying twenty days' journey to the north. 



The French River from Lake Nipissing to Lake Huron, an interval of 75 

 miles, possesses peculiar characters. It less resembles one stream, than a con- 

 fused assemblage of rivers flowing, with frequent inosculations, among length- 

 ened ridges of rock. Its shores seldom present continuous lines, bounding a 



* Long. 79° 35', lat. 44" 57'. 



t There is another large one marked in the map in long. 82" 7', lat. 46° 10', or thereabouts. 

 I never heard of it. 



