292 A NATURALIST IN THE GREAT LAKES REGION 



As one proceeds downstream to a point where the river 

 has cut down nearly to the level of the body of water into 

 which it flows it is prone to become sluggish, choke its own 

 mouth with sand or mud bars, back up and spread out over a wide 

 area of its lower flood plain, and so develop an estuary. A very 

 good example of this is seen above the mouth of the Galien River 

 at New Buffalo, Michigan (Fig. 448). Conditions are practically 

 those of the filling lake or pond. The zones of plants and animals 

 are well developed and occur in the same order as already 

 discussed in the chapter on the filling pond. 



