206 G. L. COLLIE WISCONSIN SHORE OF LAKE SUPERIOR 



scale than other streams, but this is what might be expected on the sup- 

 position that the southwest tilting of the land has crowded the waters 

 of the lake toward its head. The Saint Louis is the master stream of the 

 region. Before the tilting took place, it had eroded a much wider and 

 deeper valley than other streams had been able to do. As a result the 

 Saint Louis would naturally show the drowned features in a greater de- 

 gree than any other stream in the region. If a series of streams possess- 

 ing approximately the same size be taken between Point Detour and 

 AVest Superior, progressive drowning might be shown if the conditions 

 affecting these streams are the same. The writer has been unable to 

 find any evidence of an increase in the amount of drowning of such 

 streams toward the head of the lake. However, this proves little, for 

 local conditions may mask or wholly obliterate evidence of this kind. 

 The quite uniform conditions of drowning of streams along the Wisconsin 

 shore tends to confirm the statement alread}^ made that the direction of 

 tilting is southerly rather than westerly. Under such conditions the 

 drowning of the streams would be approximately the same all along the 

 Wisconsin shore of the lake. 



Shore Formations 



chequamegoy bay and its iiistoiiy 



The })resent bay has existed only during i)ost-Pleist()cene time, but a 

 much larger bay existed here after the folding of the Keweenawan rocks. 

 This ancient ))ay occupied one of the two minor synclines into whicli 

 the Ijake Superior synclinal was divided as a result of the folding. At 

 the opening of the Potsdam the bay had an area of at least o75 square 

 miles. This area was greatly reduced by the accumulation of Potsdam 

 sediments within the Che(iuamegon S3'ncline. Judging from the fact 

 that I'otsdam sandstone is found high on the fliinks of the syncline, it 

 is i)robal)le that the syncline was largely, if not wh(jlly, tilled by Pots- 

 dam sediments. During the interval between the close of the Potsdam 

 and the opening of the Pleistocene the sandstone was removed from the 

 syncline, in part, by the various agencies of erosion, and a new basin 

 thus resulted. During the Pleistocene the basin was modified by ice- 

 action to an unknown degree. When the present regime opened, a basin 

 of considerable size existed, ready to be occupied by the i)ostglacial 

 waters. During the Madeline stage, the area of the bay was about 75 

 square miles. Its present area is nearly 45 square miles. This area is 

 being reduced continuall}'- b}^ the encroachment of marsh deposits. The 

 water of the bay is shallow, nowhere exceeding 30 feet in depth, with an 

 average depth of less than 20 feet. A bar which has been thrown across 

 the mouth of the bay has facilitated the accumulation of sediments. 



