March 24, 1911] 



SCIENCE 



467 



western Minnesota moved to the south and south- 

 east, bringing gray till, with plentiful limestone 

 bowlders, cobbles and finer drift. This area was a 

 part of the Keewatin division of the continental 

 ice-sheet, with outflow southward from Manitoba, 

 Saskatchewan and Keewatin. In northeastern 

 Minnesota the glacial currents belonging to the 

 outer part of the broad Labradorean ice-field, 

 moved to the southwest and south, bringing red- 

 dish till, colored by the red sandstones and shales 

 of Lake Superior. The red drift is destitute of 

 limestone bowlders and detritus, because that part 

 of this state and the adjoining region northeast- 

 ward have no limestone formations. The Kee- 

 watin and Labradorean currents were confluent, or 

 they met and opposed each other on a belt that 

 extends from St. Paul and Minneapolis northward 

 and northwestward through Minnesota to the 

 vicinity of Winnipeg. 



..Wjray drift- forming the surface and overlying 

 the red drift on a large tract from Lake Minne- 

 tonka east and northeast to Eush City, Minn., and 

 to the contiguous border of Wisconsin, shows that 

 after the edge of the Labradorean ice-field had 

 occupied that area its drift was covered by an 

 advance of the edge of the Keewatin ice-field. 



Numerous sections in St. Paul, observed in the 

 distance of about three miles from the new capitol 

 to Lake Como, show that stratified drift gravel 

 and sand, mostly from the northwest, with abun- 

 dant limestone, are covered by a thin surface 

 deposit of till from the northeast, having no lime- 

 stone. The latest fluctuation of the waning iee- 

 sheet there is thus known to have been a read- 

 vance of the Labradorean margin, spreading a 

 thin mantle of its englaeial till. 



The Glacial Lake of the Fox Biver Valley and 

 Green Bay and its Outlet: S. Weidman. 

 An introductory statement was made of the 

 succession of glacial lakes in the basins of the 

 Great Lakes, and the generally accepted theory of 

 their origin by ice dams on the retreat of the 

 latest (Wisconsin) ice sheet. Professor Upham 

 pointed out the probable existence of such a lake 

 in the Fox Valley, suggesting the name Lake Jean 

 Niceollett, but not describing the shore lines or 

 outlet. Eecently discovered shore lines in the 

 valley and about Green Bay occur at about 20, 

 40, 70, 95, 150, 220 and 250 feet above the present 

 level of Green Bay. The higher shore lines are at 

 800 and 830 feet above sea-level, developed on the 

 outlet to the Mississippi Eiver by way of the Wis- 

 consin, the outlet being below the mouth of the 



Baraboo Eiver, south of Portage. The lower 

 shorelines marked stages in the lake with outlets 

 probably first through Lake Chicago and later 

 through to the Atlantic. The shore lines appear 

 to be horizontal throughout. 



The outlet for altitudes of 800 and 830 feet 

 developed across what seems to have been the 

 divide between the Pox and lower Wisconsin Eiver 

 systems, this divide being between the mouth of 

 Baraboo Eiver and Merrimac. The Wisconsin 

 Eiver above Portage was formerly a part of the 

 Fox Eiver system, and through the development 

 of the lake outlet was captured by the lower Wis- 

 consin, a tributary of the Mississippi. During 

 flood the Wisconsin now overflows to the Fox 

 across the low flats in the vicinity of the canal 

 and old Indian portage at Portage, the overflow 

 following approximately the former course. 

 Characteristics of the Glacial Drift Sheets in 



Minnesota: Frederick W. Sardeson. 



A brief historical review of recognized drift 

 sheets in Minnesota, the Old Drift, the Young 

 Drift and recognizable divisions of these, were 

 given, followed by a description of their general 

 characters. Local variations in the character of 

 the several sheets were considered with discussion 

 of means employed to identify them under various 

 conditions. The progress of new investigations by 

 Leverett and others in Minnesota was also repre- 

 sented. 

 The Pleistocene of a Portion of the Missouri 



Valley: B. Shimek. 



A discussion of the distribution and extent of 

 the Nebraskan drift, the Aftonian interglacial 

 silt, sand and gravel, and the Loveland joint clay, 

 as revealed by recent field studies. Evidence that 

 the drift of the extreme northwestern part of 

 Iowa, and adjacent territory is Kansan, and that 

 the Wisconsin is absent from that section. The 

 wide distribution of at least two loesses is noted. 

 The ^olian Origin of the Loess: B. Shimek. 



The evidence furnished by distribution, com- 

 position and fossils is briefly reviewed. Elimina- 

 tion of fossils formerly improperly included in the 

 loess series. Additional evidence furnished by 

 observations on the drifting of sands, dust and 

 snow, on plant distribution and distribution of 

 the loess along streams. A brief summary of 

 objections to all other theories of origin of loess. 

 Chains of Lalces in Martin County, Minn., as 



Evidence of Extensive Secession and Beadvance 



of the Ice-sheet: Warren Upham. Eead by 



abstract only. 



