LAKES ANTRLOPE AND SHAKOPEE 11.7 



1,17'") feet. Tliis was ni)i)arently ii short-lived stream, and lake Antelope 

 must be considered only an evanescent incident of the retreat of the ice. 

 The approximate size of tliis lake is shown on the accompanying plate, 



liaviniT heen mostly in T.ac (|ui Parlf' county. 



7. Lake Shakopee 



Tlie first of the glacial lakes of the Minnesota valley which may be 

 attributed to the ])resence of the eastern, or lake Superior, ice-lobe, as 

 distinct from the northwestern ice-lobe, is that which (illed the lower 

 reaches of the Minnesota valle}^ from Fort Snelling, or perhaps from 

 south Saint Paul, to the western limits of Scott county. It is named 

 from the city of Shakopee, whose site it covered with about 125 feet of 

 water. It should be remembered, in order to ap})reciate the complicated 

 features of the drift in this region, that this is near the meridian of the con- 

 fluence of the two great ice-lobes already referred to. Here an interlobate 

 area was enclosed, partly by the elevated lands to the south and partly 

 b}^ the ice-masses to the northeast and northwest. Evidence is abundant, 

 and has been mentioned in the reports of the Minnesota survey by Mr 

 Upham and b}'' the writer at many places, which show^s that this line of 

 confluence was a field of contention between these ice-masses, sometimes 

 one prevailing and sometimes the other, producing a superposition of 

 drift, one kind over the other, one derived from the northwest and the 

 other from the northeast, several times in succession. This is illustrated 

 not only by the alternation of red till with gra}^ but also by the laminated 

 clays wiiich were produced by the close washing of the tills, as they were 

 gathered b}^ the streams into the contiguous valleys. It must be inferred 

 that by the fluctuation of the ice on one side or the other, the nature of 

 the sediment' carried by the affluents of the Minnesota was occasionally 

 changed, or that sedimentation was wholly suspended b}^ the diversion 

 of the drainage to some other point. In order that lake Shakopee should 

 be produced by the western margin of the lake Superior ice-lobe, and yet 

 should contain prevailingly, as it does, a laminated clay derived from 

 the gray till of the western ice-field, it is evident that the western till 

 must have been already deposited and the western ice-field considerably 

 shrunken. The lake Superior lobe here early manifested its tenacity 

 of life and its ability to maintain an independent field of action farther 

 south, at this meridian, than the western ice-lobe. This is a significant 

 relation, and throws light on the later phenomena of this belt of inter- 

 lobate characters farther toward the northw^est. 



Lake Shakopee had an elevation of about 875 feet, and at some part 

 of its existence it covered the city of Minneapolis and extended up the 



XVrr— Boi.i.. Geoi,. Soc. Am.. Vor,. 12, 1000 



