656 THE ICE AGE IN NORTH AMERICA. 



chief tributaries, and all the smaller streams throughout this 

 region, flow in many places through lakes which they have 

 not yet filled with silt nor drained by cutting down their 

 outlets. At Little Falls the glacial flood-plain of the Mis- 

 sissippi is about three miles wide, reaching two miles east, 

 and one mile west from the river. Its elevation is twenty- 

 five to thirty feet above the river at the head of the rapids, 

 which have a descent of seven feet. The Mississippi here 

 flows over an outcrop of Huronian slate, and the same forma- 

 tion is also exposed by the Little Elk Eiver near its mouth, 

 on the west side of the Mississippi three miles north of Little 

 Falls. Veins of white quartz occur in the slate at both these 

 localities, and were doubtless the source of that used by man 

 here in the Glacial period for the manufacture of his quartz 

 implements. 



The locality and section of the modified drift, where these 

 worked fragments of quartz were found by Miss Babbitt, 

 and the account of their discovery, are best told in her own 

 words from her paper read before the Anthropological Section 

 of the American Association for the Advancement of Science 

 at its Minneapolis meeting in 1883. I quote as follows : 



"Rudely worked quartzes had previously been discovered 

 here by the State Geologist of Minnesota, Professor N. H. 

 Winchell, by whom they had been described and figured in 

 the State Geological Report for 1877. . . . The find reported 

 by Professor Winchell consists of chipped objects of a class 

 generally ascribed to what is called the rude stone age. Of 

 these many appear to be mere refuse, while others are regarded 

 as finished and unfinished implements. The Winchell speci- 

 mens have been assigned, upon geological ground, to a pre- 

 historic era antedating that of the mound-building races, and 

 reaching back to a time when the drift material of the terrace- 

 plain was just receiving its final superficial deposit. It is 

 found that, at intervals, the surface soil of the terrace con- 

 tains these quartzes to a depth of not unfrequently three or 

 four feet. 



"The lowest and newest formation at this place is the 

 present flood-plain of the river. It is still in process of depo- 

 sition, being yet subject to partial overflows at periods of 



