THE MODERN GREAT LAKES 



features of the Great Lakes are unique, it is not surprising; to 

 lind that the delta of St. Clair River is most unusual, for it 

 is built by a stream flowing from one lake into another. 

 Earlier in the story we found that this river had to cut across 

 the Port Huron moraine, south of Port Huron, in order to 

 carry the waters of the glacial lakes. Thus the present river 

 acquired some tools which had been left in the channel when 

 the former stream became sluggish or disappeared. These, in 

 small amount, the present river has ground up, carried into 

 Lake St. Clair, and dropped when the current was slackened 

 in the quiet waters of the lake. The delta has been increased 

 in size — principally after all the morainic materials were car- 

 ried away — by sediments which have been washed by storm 

 waves from the Lake Huron shores. In the narrow southern 

 part of Lake Huron waves are cutting material from the 

 Canadian shore; the coarse material is deposited on the Cana- 

 dian side at Point Edward, but the finer is being carried by the 

 river to the American side, building the delta — the famous 

 St. Clair flats — farther out into Lake St. Clair. 



The narrow part of Detroit River, between Belle Island 

 and Delray, is the part of its channel cut across the moraine 

 which separated the Erie and the Huron ice lobes and which 

 for a time held the waters of Lake St. Clair at a higher level. 

 At first the river flowed across the moraine in several chan- 

 nels, but eventually it deepened the present channel opposite 

 Detroit and drew all the overflow from Lake St. Clair through 

 one channel. Then for a time the river widened, as far 

 south as Crosse Isle, into small Lake Rouge which existed long 

 enough to build a distinct beach. Many of the older cottages 

 on Grosse Isle are built on the Rouge beach. South of Wyan- 

 dotte the river once entered Lake Erie through many chan- 

 nels or distributaries, and probably built a delta of the ma- 

 terials it washed from the broad flat moraine which it crosses 

 at Trenton. But lifting of the lake level has submerged the 

 delta front, and deepening of the river has drawn the water 



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