124 SKETCHES OF CREATION. 



Fig. 56. A remarkable Silurian Sea-weed (Arthrophycits Harlani). From the 

 Medina Sandstone of the Niagara Group. 



tion through which, with others, the Niagara River has cut 

 its way. In another connection I shall have something 

 farther to say in reference to this stupendous piece of 

 Nature's engineering. From the falls of Niagara the out- 

 cropping belt of this limestone runs in lines parallel with 

 those just traced. It forms the promontory of Cabot's 

 Head, and the peninsula separating Georgian Bay from 

 Lake Huron. At this point the formation has succumbed 

 to the attacks of the waves, and disappears in its north- 

 Avestward trend beneath the water of the lake. Cropping 

 out again, it forms the remarkable chain of the Manitoulin 

 Islands, in the northern part of Lake Huron, including 

 Drummond's Island. Beyond St. Mary's River it forms a 

 " point" and a peninsula, the counterparts of Cabot's Head 

 and the peninsula to the south of it. Running westward, 

 and then south westward, it establishes a continuous barrier 

 to Lake Michigan along the northern and western borders, 

 constituting the rocky ridge which isolates Green Bay 

 and Bay de Noquet from the greater lake. It follows the 



