TERMINAL MORAINES. 223 



eating points where there was a marked pause in the retreat 

 of the front, affording time for a considerable accumulation 

 of material, and perhaps sometimes of a short advance. 

 These well denned morainic deposits mark a movement from 

 Labrador as a center, and over a considerable area overrode 

 earlier deposits which had been laid down by the movement 

 from the Keewatin center west of Hudson's Bay. The Wis- 

 consin moraines are well developed across New Jersey and 

 Pennsylvania down to the line surveyed by Professor Cook 

 and by Lewis and Wright as marked on our map. West of this 

 the glaciated area in Ohio and Indiana was covered with Wis- 

 consin drift down close to the southern border; while in Illi- 

 nois it reached well down towards the center of the state, and 

 in Iowa projected in a well defined loop as far as Des Moines, 

 and in the Dakotas extended to the Missouri River. 



An earlier movement from the same center is denominated 

 the Illinoisan. This projected beyond the Wisconsin deposits 

 over nearly all the western portion of Illinois, and crossed the 

 Mississippi River for a short distance in the neighborhood of 

 Burlington, compelling the river to flow for a short period in 

 a new channel that can be traced from Clinton to Lee County, 

 Iowa. Jaspar conglomerate bowlders from north of Lake 

 Huron are found, with more or less frequency, over the whole 

 region covered by the Wisconsin and Illinoisan deposits 

 lying west of Pennsylvania and southeast of a line connecting 

 Des Moines, Iowa and Green Bay, Wisconsin. 



Outside of the Illinoisan area there is in Iowa a still earlier 

 pretty well defined series of deposits called the Iowan. Mr. 

 Leverett, however, does not now feel like recognizing these 

 as distinct from the other deposits. But there is a very well 

 defined line some distance outside the Wisconsin deposits, 

 running across the state from east to west and nearly through 

 the middle, separating an area which is covered by loess and 

 one which is bare of loess, the loess evidently having been 

 derived from the ice of the northern portion as it was swept 



