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CAPE COD GEOLOGY 



295 



that is, at Provincetown and Monomoy, and along the Barnstable beach. Many 

 other small dunes are found on the shore of the open sea, along the sound on the 

 south, and along the shore of the bay, where the beaches furnish the sand. The 

 dunes of Provincetown are the best known in this part of the coast. 



DUNES OF THE PROVINCELANDS 



The dunes of the Provincelands are the highest along the southeastern coast 

 of New England. They form three distinct belts or tracts, each showing some 

 peculiarity of form and arrangement. The outermost belt skirts the beach from 

 Race Point to the place where the Provincetown sand hook is attached to the 

 glacial headland between High Head and the Highland Lighthouse. This 

 region is of recent origin. Here the beach and the dunes are partly separated 

 from the main tract by the slough known as Race Run, a slight depression 

 that runs nearly continuously through the district. The Peaked Hills, which 

 stand between 2 and 2\ miles from Race Point Lighthouse, were the chief ac- 

 cumulations of wind-blown sand in this belt in 1835 (Plate 35, fig. 2). On 

 Graham's chart, which is based on surveys made in 1833-35, the highest points in 

 these dunes are given as 44 and 46 feet. Farther east individual dunes reached 

 elevations of 49, 52.5 and 54 feet, the last one lying just east of the boundary 

 line between Provincetown and Truro. East of High Head, near the junction 

 of the sand hook with the mainland of the Cape, there is a group of old wooded 

 dunes, one of which is known as "the island." These dunes are probably a part 

 of an older deposit than that at Peaked Hills, having been formed when the 

 beach joined the mainland at a point east of its present position. These outer 

 dunes are now considerably reduced. 



On the south side of the Race Run slough there is a second belt of more 

 stately dunes, which form a nearly continuous ridge that extends from the 

 northwest side of East Harbor, or Pilgrim Lake, to a point within about a mile 

 of the west coast On Graham's chart the highest dune indicated in Provincetown 

 had an elevation of 64 feet, and one in Truro, near the west end of Pilgrim 

 Lake had an elevation of 85 feet. Much of the surface of this dune, as shown 

 on the chart, was covered and anchored by transplanted beach grass. (Plate 36, 

 fig. 1). The survey of 1887 shows that this ridge of dunes had increased in 

 elevation near its east and west ends, two points near the west end and three 

 near the east end, rising above 80 feet. 



According to a survey made by McClintock in 1892 the great ridge had risen 

 above the height shown by Graham's survey, at one point attaining an elevation 



