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CAPE COD GEOLOGY 



Harbor northward to Highland Light, has been gradually reduced by the inroads 

 of the sea ever since the country was settled, and although small areas of beach 

 flats are built up from time to time between headlands or at the east side of 

 the end of the Cape, the total area of the Cape is reduced a few acres every year. 



TOPOGRAPHY 



The Cape Cod district is a partly submerged mass of glacial material, which 

 consists of the Plymouth interlobate moraine on the west side of Cape Cod 

 Bay, other interlobate glacial deposits on the east side of the Bay, and a lobate 

 moraine whose frontal outwash plain extends from Chatham to Falmouth and 

 is bordered on the west by the moraine of a glacial lobe that lay west of the 

 Plymouth interlobate axis. Cape Cod Bay lies in the broad, shallow depression 

 that was occupied by the glacial lobe about which the deposits of the Cape 

 are grouped. 



The south side of the Cape along the shore of Buzzards and Cape Cod bays 

 is traversed by morainal hills, which in places in and near the town of Sandwich 

 reach a height of 200 feet above sea level. The plains south of this belt of morainal 

 country rise to the same elevation as the hills in Sandwich and decline southward 

 to or nearly to sea level, although they usually confront the Sounds with a low 

 bluff. The inner limit of the plains decreases in height both ways from the 

 axis of the moraine in the northern part of the town of Sandwich, south of the 

 Manomet creek passage. 



The arm of the Cape from Nauset harbor northward consists of three well- 

 defined plains, which lie back of the morainal belt. Two of these tracts, the 

 "Nauset" or Eastham plain and the plain in North Truro (see Plate 25, fig. 2), 

 stand between 60 and 70 feet above sea level. Between them lies the deeply creased 

 high plain of Wellfleet and Truro, whose surface attains a height of 150 feet. 

 The tip of the Cape is formed by a large hook of beach sand and dunes, partly 

 enclosing Provincetown harbor. Another large sand bar, or a series of sand 

 bars, lies at the southeastern versant of the Cape. In the coastal lagoons and in 

 the inlets, particularly those bordering Cape Cod Bay, there are large tracts of 

 marshland. 



On the side of the Cape facing the ocean there are steep cliffs of gravel and 

 sand, and on the arm of the Cape, in Wellfleet and Truro, on the Bay side, there 

 are lower cliffs. The action of the sea on the side where it has been most effective 

 has given a graceful curve to the coast line. 



The Cape Cod peninsula forms the northeastern emerged part of the Atlantic 



