LE SUEUR COUNTY. (541 



Terminal moraines.] 



and had retreated great distances from its farthest limit. When its first 

 or Altamont moraine was accumulated at the extreme boundary of the ice 

 in this epoch, it reached south to Des Moines; when the second or Gary 

 moraine was formed, it terminated on the south at Mineral ridge, in Boone 

 county, Iowa; at the time of the third or Antelope moraine, it had farther 

 retreated to Forest City and Pilot mound in Hancock county, Iowa; the 

 fourth or Kiester moraine was formed when the southern extremity of the 

 ice-lobe had retreated across the south line of Minnesota and halted a few 

 miles from it in Freeborn and Faribault counties; and the fifth or Elysian 

 moraine, crossing southern Le Sueur county, marks the next halting-place 

 of the ice in its recession northward. At the time of formation of this fifth 

 moraine the south end of the ice-lobe had been melted back a hundred and 

 eighty miles from its farthest extent, and its southwest side had retired 

 thirty to fifty miles from the crest of the Coteau des Prairies to the east side 

 of Big Stone lake and the east part of Yellow Medicine county; but while 

 these great changes in the area of the ice-lobe were taking place, its eastern 

 boundary in Rice and Le Sueur counties had fluctuated only slightly, so 

 that a broad compound morainic belt there represents the five moraines 

 which were formed on the south and west. During the next recession of 

 this ice-lobe, it was melted away from the whole of Le Sueur county, and 

 its southeast extremity was withdrawn to Waconia in Carver county, 

 where it again halted, forming its sixth or Waconia moraine.* 



It is evident that when the ice began to retreat its increased melting 

 caused the prevailing westerly winds, sweeping over the western side of 

 the ice-sheet upon the Coteau des Prairies and eastward, to become more 

 laden with moisture than in the earlier part of this epoch when there was 

 comparatively little melting upon the surface of the ice in this latitude; 

 and that the increased temperature enabled these winds to carry their 

 moisture farther than when. the ice had its greatest extent. As a result, 

 the snow-fall became greater than before upon the east portion of this ice- 

 lobe, maintaining and even in part enlarging its area on that side during 

 the early stages of the recession from its farthest limit southwestward.f 



*Comparc pages 406, 463, 478, 581 , 605-6 and 621 . 



tThe climatic conditions indicated by the unequal rates in the final melting of the west and east sides of this ice- 

 loin-. \\crr lirst pointed out in a paper entitled "Changes in the currents of the ice of the hist glacial epocli in eastern 

 Minnesota.'' Proc. Amcr. Assoc.for Adv. of Science. 18S3. 



41 



