CHAPTER IX 



THE BEARING OF THESE STUDIES ON PREVIOUS 

 WORK AND ON NEW PROBLEMS 



Previous Knowledge of the Ice Retreat 



The map compiled by Goldthwait (PI. VI) illustrates the 

 retreat of the last ice sheet in the Northeastern States. It shows 

 the general direction of the ice flow as based on striae, drumlins, 

 and boulder trains and the outermost limit marked by the 

 terminal moraines; it shows interruptions of the ice retreat as 

 recorded by recessional moraines and other phenomena; it 

 indicates the late glacial marine submergence of the coast 

 region north of Boston and the rate of recession of the ice front 

 as worked out by the clay studies. 



The ice flow, seen on the map, is, so far as can be judged, that 

 which prevailed during the time of the ice retreat. The center of 

 the ice lobe covering the Northeastern States followed the great 

 topographical lines, the Champlain-Hudson lowland and the 

 Green Mountains, which trend north and south, and flowed 

 directly southward across Vermont. In southern New England, 

 where the relief is less marked and where the ice flow was strong 

 in the valleys but weak in the lee of the highlands, subordinate 

 lobes were developed in the Hudson and Connecticut Valleys. 

 East of the Connecticut River the ice movement diverged toward 

 the southeast. West of the lower Connecticut the motion was 

 somewhat westerly. In the lower and central Hudson region 

 the ice spread strongly toward both sides. 



During the ice recession the Hudson lobe retired more slowly 

 than the Connecticut lobe and deployed. It invaded western 

 Connecticut and Massachusetts, crossing the earlier direction 

 of the ice flow. The ice front in the Berkshires, as revealed by 

 Taylor's (1903) studies of the recessional moraines, had a 



