1887.] 447 [Upham 



the whole Mississippi basin southward, and this was the first spot 

 accessible whence quartz for implement-making could be obtained. 

 While the deposition of the valley-drift at Little Falls was still 

 going forward, men resorted there, and left, as the remnants of 

 their manufacture of stone implements, multitudes of quartz frag- 

 ments. By the continued deposition of the modified drift, lifting 

 the river upon the surface of its glacial flood-plain, these quartz 

 chips were deeply buried in that formation . The date of this valley- 

 drift must be that of the retreat of the ice of the last glacial 

 epoch, from whose melting were supplied both this sediment and 

 the floods by which it was brought. The glacial flood-plain, beneath 

 whose surface the quartz fragments occur, was deposited in the 

 same manner as additions are now made to the surface of the bot- 

 tom-land ; and the flooded condition of the river, by which this 

 was done, was doubtless maintained through all the warm portion 

 of the year, while the ice-sheet was being melted away upon the 

 region of its head waters. But in spring, autumn and winter, or, 

 in exceptional years, through much of the summer, it seems prob- 

 able that the river was confined to a channel, being of insufficient 

 volume to cover its flood-plain. At such a time this plain was the 

 site of human habitations and industry. After the complete dis- 

 appearance of the ice from the basin of the Upper Mississippi, the 

 supply of both water and sediment was so diminished that the 

 river, from that time till now, has been occupied more in erosion 

 than in deposition, and has cut its channel far below the level at 

 which it then flowed, excavating and carrying to the Gulf of Mexico 

 a great part of its glacial flood-plain, the remnants of which are 

 seen as high terraces or plains upon each side of the river. 



A general discussion followed, and Professor Haynes showed 

 from his collection, some slightly weathered implements of palae- 

 olithic forms which he did not consider to be palaeolithic imple- 

 ments. 



Professor Morse alluded to the care with which these questions 

 are now studied and the significance of the results obtained. 



The President concluded the discussion, stating that all these 

 discoveries of recent years show that man had occupied a por- 

 tion of North America, from the Mississippi river to the Atlantic 

 ocean, at a time when the northern part of the United States was 

 covered with ice, and that at this early period he must have been 



