CAPE COD GEOLOGY 



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around the end of the glacial part of the Cape, forming the headland known as 

 Pilgrim Heights, or Pligh Head, in North Truro. 



High Head, or Pilgrim Heights, is cliffed in three directions, none of which 

 coincides with the present trends of long-shore marine action. On the north side 

 of the head there is an old, somewhat dissected cliff which is about 2 miles long 

 and is separated by the "Salt Meadow" from the dune-crested beach that joins 

 the Provincelands on the ocean side to the end of the Cape near Highland 

 Light Coast Guard Station. This cliff is regarded by Davis as a remnant of 

 an early, outer coast line of the headland of Cape Cod, a line that existed 

 about 1,200 years ago. As the coast of the ocean or "back" side of the Cape 

 retreated under the action of the sea and straightened out, the flying beach 

 would spring off from the head of the Cape near B and the sandy hook beyond 

 the point of contact with the coast would grow outward. Thus the oldest 

 part of the hook at Provincetown is on the inside next the harbor and the 

 newer part on the north. 



The cliff on the west side of High Head is older and is apparently contem- 

 poraneous with that on the north, behind the Salt Meadow, cut before the 

 flying beach and hook at Provincetown began to form, and a newer one farther 

 south which, as it lies farther east, has sent off a flying beach from the head 

 enclosing Pilgrim Lake, or East Harbor, as the lagoon was called before this 

 beach united with the main beach. 



In 1916 Vaughan observed on the outer beach, near Woods End, at low 

 tide, a small area of angular gravel of glacial origin that seems to be abnormal 

 for the hooked spit there, which appears to rest upon an older deposit. This 

 gravel must have formed a shoal before the Woods End spit was built out to 

 its present outline. As the cliffs at Pilgrim Heights indicate an open sea when 

 they were cut, the time of the removal by wave action of glacial deposits there 

 that lay above sea level was probably the time the shoal was formed. The shoal 

 and any island or land that lay in that position would have given direction 

 and support to the sand-spit that now forms the outer barrier of the harbor. 

 The gravel recalls the Jameco (?) material underlying the Gardiners (?) clay 

 at Highland light, and this material extended over the site of Provincetown 

 harbor before the land was cut away to form the cliffs at Pilgrim Heights. 



The Provincetown wing-bar has undergone little change since it was first 

 mapped. In 1857 Whiting found by comparing late maps with those made 

 by the survey of 1849, that the changes were most pronounced near Race Point 

 and East Harbor. Lance's Harbor had been closed, and the enclosing beach 



