48 



CAPE COD GEOLOGY 



gravel of Fuller, the type occurrence of which was stated by him to be on Long 

 Island, New York. The deposit was interpreted by him as indicating an advance 

 of the ice, but he reported no till or signs of direct ice action. 



Many of the beds are ferruginous, and some have a thickness of twenty feet 

 or more. This gravel lies beneath the Gardiners clay in Mohegan bluffs, on the 

 south side of Block Island; on the south side of No Mans Land; and in Nasha- 

 quitsa cliffs, on the south side of Marthas Vineyard. Probably the gravel beneath 

 the clay at Highland Light, on Cape Cod, are at this horizon. 



The typical Jameco gravel appears to be a stream deposit like those washed 

 out from glacial fronts in low grounds or near the sea at the present day. 



Moshup Till Member. A remarkable upturned bed of boulder clay that was 

 exposed in Nashaquitsa cliffs, on Marthas Vineyard, for a quarter of a century 

 prior to 1916, occupies, at least in part, the stratigraphic position that is else- 

 where held by the Jameco gravel. It lies below the Gardiners blue clay and 

 above the beds of sand and gravel that are here called the Weyquosque formation. 

 (See Fig. 12 and Plate 23). On No Mans Land a similar boulder bed was exposed 

 in 1915 and 1916 beneath the Gardiners clay. These deposits of true boulder clay 

 confirm an inference drawn by Fuller from the occurrence of the Jameco gravel — 

 that the deposition of the Gardiners clay was preceded by a glacial invasion and 

 that the Jameco gravel is a product of that invasion. At one place on the north 

 shore of Marthas Vineyard, as already noted, a bed of stony blue clay lies be- 

 neath the Gardiners clay. The exposures showing the position of this bed and of 

 its supposed correlative beds of stony clay indicate that it replaces locally the 

 upper part or all of the Jameco gravel and lies immediately below the stratified 

 Gardiners blue clay. In Nashaquitsa cliffs the bed is less than ten feet thick. It 

 is decisive evidence of the second stage of glaciation on Marthas Vineyard. Ful- 

 ler found no equivalent till on Long Island, and it has not been observed on Block 

 Island. It has not been certainly recognized east of Marthas Vineyard. 



In conformity with the example set by Fuller in giving the name Montauk 

 till member to the bed of boulder clay that divides the Manhasset formation on 

 Long Island, this bed of till is here called the Moshup till, from the name of a 

 local god in the aboriginal folklore concerning the origin of Gay Head. Like the 

 Montauk till, it is not a continuous sheet. 



GARDINERS INTERGLACIAL STAGE 

 Gardiners Clay 

 Distribution and character. — Beds of a dark blue clay, which are usually 

 folded, are exposed at several places on the islands from Marthas Vineyard west- 



