8 4 



most part by the remains of siphuncles. Numerous gas- 

 tropods and pelecypods also occur. The residual lime- 

 stone and arkose, seen in the cavities in the granite, are 

 essentially similar but lie at an elevation of 50 or 60 

 feet (15 to 18 m.) above the limestone on the shore. As 

 the original hollows in the granite could not have been of 

 great depth and as the length of time since the deposition 

 of the limestone has not been sufficient to entirely wear 

 them out, it follows that the total erosion of the granite 

 since Lowville time has not been very great. 



THE MOHAWKIAN (MIDDLE ORDOVICIAN) 



STRATA NORTHEAST OF MANITOULIN 



ISLAND. 



BY 



August F. Foerste. 



Little Current — Alt. 579.86 ft. 176.3 m. — Little 

 Current is the most important town on Manitoulin island. 

 The narrow channel between Manitoulin and Goat islands, 

 at this locality, forms the eastern exit for the lumber 

 traffic along the waters of the North Passage. Lumber 

 rafts are sometimes held up two or three days by the 

 peculiar currents (seiches) which have given the village its 

 name. These are due to the wind. When the wind blows 

 strongly for several days in one direction it heaps up the 

 water on one side of the passage at Little Current, and 

 lowers it on the other sufficiently to start a current, the 

 direction of which depends on the direction of the wind, 

 whether from the east or from the west. Hence, such 

 names as Little Current and Swift Current. 



The most striking geological feature of the territory 

 bordering the channel north of the main body of Lake 

 Huron is the deposition of Ordovician strata upon a fairly 

 rugged Pre-Cambrian topography. Here, strata as early 

 as the Lowville clays and limestones, and as late as the 

 Trenton and the immediately overlying Cincinnatian s ata 

 rest directly upon quartzites and schists mapped by the 

 Geological Survey of Canada as Huronian. There is 



