S. P. Thompson— Resistance of Carbon. 433 



had moved southwestward over the region, and deposition of 

 moraine material had taken pJace. The high-level prairie 

 either side of the lake region and of the Minnesota valley is 

 made largely of this unstratitied drift; but the generally level 

 surface in the part toward the lake region and valley, a"nd the 

 tion in much of the material, are evidence that the 

 flood from the melting glacier covered and levelled it, and 

 stratified its bedded deposits ; the coarseness of these deposit?, 

 and the large size of the vidley of discharge, that the flood 

 waters had great velocity; the height of the prairie, (hat 

 they stood 100 to 150 feet above the present level of the 

 ■ ling Lake Traverse, instead of the 40 feet at the 

 divide above supposed. This time of maximum flood and 

 of rather violent fluvial conditions was followed by the era 

 ''I the Great Lake, that is, of quiet waters and lacustrine 

 deposits, with slow discharge over the Lake Traverse region ; 

 which may have been brought about in part by diminished 

 supply of waters from the melting ice and precipitation, but 

 more, with little doubt, by a diminution in the slope of the 

 general surface, which was a part of the great change of slope 

 that went on, as explained by General Warren, until the land 

 w as reduced to its present pitch and the streams to their 



'•pinents in Central North America is that of General 

 Warren. But rather than use either, it is better to 

 accepted name, Lake Winnipeg, be the name for past, 



Art. XLYIII— Note < 



In the July number of this Jouri 

 hall has described some experiment 

 anee in a disk of prepared lamp-bla 

 S( >n's tasi meter. At the close of hi 

 Mendenhall ventures, " without kn 

 nature of these experiments," to cal 

 made by Professor \V. F. Barrett, 1 



