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CAPE COD GEOLOGY 



Quaternary System 



By Edward Wigglesworth 



PLEISTOCENE SERIES 



The remarkable abundance and variety of the Pleistocene deposits on 

 Marthas Vineyard reveal much more Pleistocene history than can be deciphered 

 at other places in New England, where the Wisconsin deposits dominate all 

 other glacial phenomena. On Marthas Vineyard the reverse is the rule, the 

 Wisconsin deposits form only an insignificant part of the Pleistocene beds, 

 and only the earlier ice of Wisconsin time extended so far south. The series is 

 very nearly the same as that on Long Island, New York, but no exact corre- 

 lations of the earliest deposits can be made. These deposits and their probable 

 correlation are more fully considered by Professor Woodworth in Part I of this 

 report. The series, as made out, is as follows: — 



Wisconsin moraine and outwash 



C Hempstead gravel member 

 Manhassett formation \ Montauk till member 

 I Herod gravel member 

 Jacob sand 

 Gardiners clay 



Moshup till member; at Nashaquitsa cliffs 



Coarse gravel of typical Jameco type; at Gay Head and Nashaquitsa 



cliffs 

 Ferruginous boulder bed; at Gay Head 

 Mannetto formation: at Gay Head cliffs 

 Weyquosque formation : at Gay Head and Nashaquitsa cliffs 

 Dukes boulder bed: at Gay Head cliffs 

 Aquinnah conglomerate : at Gay Head cliffs 



EARLY PLEISTOCENE DEPOSITS (PRE-GARDINERS FORMATIONS) 

 The lowest formations of the Pleistocene series, including all those laid 

 down before the deposition of the Gardiners clay, are clearly exposed in only 

 two small outcrops, one in the Gay Head cliffs, the other in the Nashaquitsa 

 cliffs. Small exposures of what are thought to be the same beds occur at five 

 other places, notably at Norton Point. Only in the two cliff sections are the 

 beds well enough exposed to justify an attempt to interpret their relations, but 

 the exposures are so small and so obscure that the interpretation made can be 

 regarded as only tentative. The interpretation proposed does not agree with 

 that proposed for the deposits on Long Island that preceded the Jameco, as 

 described by Fuller, 1 which consist solely of a gravel called the Mannetto gravel. 



1 Fuller, M. L., Geology of Long Island, New York, U. S. Geol. Surv. Prof. Paper 82, pp. 80-92, 1914. 



Jameco formation 



