278 



CAPE COD GEOLOGY 



axis appears to have melted out faster than the lobe lying in Cape Cod Bay, 

 for there are similar high plains of stratified drift that slope westward and south- 

 westward from the axis of the lobe into the basin vacated by the ice of the 

 Buzzards Bay lobe. This earlier melting of the ice on the western sides of the 

 interlobate axes in these two fields may mean that the ice was thicker and main- 

 tained longer, more vigorous advance over the Bay of Maine than over southern 

 New England. This difference may not have arisen so much from inequality in 

 the snowfall in the eastern and western parts of northern New England and the 

 adjacent gathering grounds on the north as from the fact that, in Vermont and 

 New Hampshire, the ice sheet encountered high mountain barriers that restricted 

 its flow to the southern part of the field after the Labrador ice sheet began to 



PRESENJ. 

 SEA LEVEL 



Fig. 22.— Theoretical cross-section of Cape Cod interlobate axis, Cape Cod Bay, and the Plymouth interlobate axis, with the 

 Wisconsin ice sheet at the Falmouth substage. 



melt. Farther east, over the site of Maine, broad lowlands stretched between 

 the White Mountains in New Hampshire and Mount Bigelow, and between 

 Mount Bigelow and Mount Katahdin. Another result of this freer flow of ice 

 across Maine and east of Massachusetts is the apparent extension of the ice 

 front, at least at the Nantucket substage, southeastward from Nantucket over 

 Nantucket shoals and Georges Bank. 



The accompanying theoretical cross section (Fig. 22) in the latitude of 

 Manomet Hill near Plymouth and the high plain near the Highland Lighthouse 

 shows the relation of the ice sheet to the glacial formations before the ice sheet 

 disappeared from the vicinity of Cape Cod Bay. Some such relation between 

 the lobes of the ice sheet and the deposits made or left in the interlobate axes 

 out of the path of maximum motion and most effective erosion of the ice 

 began to give shape to the features of the land in the earlier ice advances. 



