210 matured 



whole of North America north of the line of 

 the terminal moraine that we have traced is 

 a glacial region, with the exception of a few 

 hundred square miles chiefly in Wisconsin, 

 where the ice seemed to have parted and 

 passed around this area, coming together 

 again on the south side of it. The ice prob- 

 ably did not reach the extreme limit that 

 shows glacial deposit, but undoubtedly the 

 effects of it are seen for some distance to the 

 south, owing to the fact that during the time 

 it was melting great quantities of water flowed 

 away from the extreme edge of the ice, carry- 

 ing with it more or less of the glacial drift, 

 which was deposited for some distance to the 

 south. When the ice receded it undoubtedly 

 paused at different points, where it remained 

 stationary for a long period of time. I mean 

 stationary at its edges, for the flow of ice was 

 continually moving, but in its progress south- 

 ward it came to a point where the heat waa 

 sufficient to melt the ice as fast as it arrived 

 at that point. The on-moving ice was con- 

 tinually bringing with it the debris that it had 

 gathered up at different points on its journey, 

 so that it is easy to see how these moraines 

 could accumulate to a greater or less depth at 

 the margin of the ice flow, which would be de- 

 termined by the duration of the period it re- 

 mained stationary. This, however, is only 

 one factor, as the surface of the earth in some 



