CAPE COD GEOLOGY 



269 



have thrown the sand into beaches at scores of places that were identical in 

 exposure to those under which the beaches of the coast are found. 



FALMOUTH SUBSTAGE 

 Falmouth Moraine 



The Falmouth moraine forms the boulder-strewn belt of high ground 

 (Plate 34, fig. 1) that extends from Nauset Head, in Orleans, westward through 

 the northern part of the main arm of the Cape to Manomet Creek, where it 

 turns southwestward to Woods Hole and is continued in the Elizabeth Islands. 

 In Orleans this frontal moraine is scarcely distinguishable except by its boulders 

 and a slight thickening of the till over the older gravel and sand of the pre- 

 Wisconsin glacial deposits on which it rests. The small glacial erratics on the 

 surface about Chatham village and farther north, together with the deeply in- 

 dented coast line, suggest that the ice front turned sharply southward at Orleans 

 and that the edge of a lobate moraine covered the necks of land as far south as 

 Chatham and thence ran out to sea. This part of the frontal moraine contains 

 little drift in the angle between the off-shore lobe just mentioned and the lobate 

 moraine that runs westward to Buzzards Bay. Just west of Orleans, however, 

 the moraine becomes higher and thicker. The thickness of its beds of till or 

 boulder clay increases, as well as the thickness and breadth of the outwash sand 

 and gravel. From this point westward the outwash plain increases in size 

 through the towns of Brewster and Dennis. They are highest and broadest 

 just where the Cape peninsula is widest. In Yarmouth and eastern Barnstable 

 the moraine diminishes in breadth and continuity and the confronting plain is 

 correspondingly low and narrow, the change occurring nearly in the middle of 

 the arc formed by the ice front that lay between the interlobate axis traversing 

 the eastern arm of the Cape and that traceable from Plymouth to the angle 

 near the Cape Cod Canal. West of Barnstable village the morainal belt grad- 

 ually rises in height from 100 feet to more than 200 feet and reaches a height 

 of 207 feet in Bourne's Hill, south of Sandwich, the highest point in the Falmouth 

 moraine. 



The highest points on Marthas Vineyard, Prospect Hill (308 feet) and Peaked 

 Hill (311 feet), in the Nantucket moraine, owe their height almost entirely to 

 older formations, whose topography was determined chiefly during the Vineyard 

 interglacial stage. Manomet Hill, the highest point on the west coast of Cape 

 Cod Bay in the Plymouth interlobate moraine, has an elevation of 394 feet. 

 The hill is covered with till, but underneath the till there are beds of stratified 



