CAPE COD GEOLOGY 



251 



Mr. M. C. Atwood, Deputy Collector of Revenue at Provincetown, informed 

 me in April, 1916, that a well was drilled at the end of Central wharf to a depth 

 of 400 feet many years ago. The material passed through was a light gray 

 clay. No good water was found. 1 



Mr. Elmer C. Smith told me in 1916 at Rock Harbor that in about 1890 

 a well was sunk on his father's land in East Orleans, near the point where the 

 road branches off to go to Pochet Neck. No water was found at a depth of 70 

 feet, but farther down the drill passed through from 2 to 3 feet of blue clay at 

 a depth of 84 feet and then entered a bed of shells in "beach gravel." The well 

 was drilled at a point about 50 feet above sea level. This shell bed is probably 

 brought up by an anticlinal fold in the Sankaty sand. The washing away of 

 the banks about the crooked inlets between Nauset Harbor and Namequot 

 Point may expose this shell bed above sea level. 



The Sankaty sand occurs in Sankaty Head bluff and probably reappears 

 above sea level in the eastern part of Orleans. Its discovery in the wells at Prov- 

 incetown between 200 and 360 feet below the surface indicates that it underlies 

 the arm of Cape Cod and that it is distributed along the coast of eastern Massa- 

 chusetts. Beds containing its fauna have not been found on Marthas Vineyard, 

 where, however, there are beds of Pliocene sand containing Macoma lyelli, a 

 species not found living elsewhere and particularly abundant in the underlying 

 Miocene greensand. 



In his correlation table of Pleistocene formations about the coast and islands 

 of southeastern New England, Fuller 2 placed the fossiliferous beds at Sankaty 

 Head at the horizon of the Jacob sand, a formation that lies upon the Gardiners 

 clay and under the Herod glacial gravel, but the position of what appears to be 

 the Gardiners clay and Jacob sand in the bluff at Highland Light, a few miles 

 southeast of the Provincetown well, suggests that the Sankaty sand lies below 

 the section at Highland Light and that the Jameco gravel is the visible base 

 of that section. The Sankaty sand, with its marine fossils, probably lies at the 

 horizon of the Weyquosque glacial sand and small gravel — that is, it lies very 

 near the base of the Pleistocene series. Its assignment to this horizon agrees 

 closely with Dall's opinion that it represents the upper Pliocene; but just as 

 the Weyquosque glacial sand and gravel at Clay Head on Block Island and 

 at Gay Head and in Nashaquitsa cliffs on Marthas Vineyard are underlain by 

 beds of boulders or by pebbles containing granitic material, so at Sankaty 



1 Charles W. Johnson, Fauna of New England, list of the Mollusca: Occasional Papers of the Boston 

 Society of Natural History, 8, No. 13, Boston, 1915, p. 19. 



^ Prof. Paper 82, U. S. Geological Survey, Washington, 1914, p. 220. 



