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CAPE COD GEOLOGY 



Pre-Wisconsin Deposits 



The deposits in the cliffs may be separated into stratigraphic units below 

 the uppermost beds of gravel and sand, which are the "kames" described by 

 Shaler. These beds, however, are remnants of the Hempstead gravel, which 

 overlies the Montauk till. The Montauk till is strikingly displayed and con- 

 tains boulders, the largest 6 feet across. This till is hard and compact and 

 withstands erosion so well that in places it forms projecting buttresses in the 

 face of the cliffs (See Plate 27, fig. 2). In a part of the cliffs that faces south- 

 west two beds of such till and intervening deposits of stratified sand and clay 

 may be seen (Plate 28, fig. 1), but here there may be some duplication by over- 

 thrust. The Gardiners clay is well exhibited at several places. At one place on 

 the south coast (see Plate 27, fig. 1), the Gardiners clay, as seen in 1915 and 



Fig. 18. — Contorted Pleistocene beds on the east coast of No Mans Land. A, Moshup till member, 10 feet thick, exposed 

 above the beach; B, laminated blue Gardiners clay; C, sand, apparently at the horizon of the Jacob sand. The Moshup 

 till is regarded as a till phase of the uppermost part of the Jameco gravel. 



1916, rested on a boulder clay, evidently the lower till mentioned in Shaler's 

 report of 1888. This till bed beneath the Gardiners clay should be compared 

 with the section at Nashaquitsa, where a similar bouldery bed (the Moshup till) 

 has been exposed for several years in an upturned position, apparently uncon- 

 formable below the Gardiners clay. (See fig. 18, and Plate 23, fig. 1). The till 

 at both these places seems to replace the Jameco gravel as the foundation on 

 which the Gardiners clay rests. The accompanying plate (Plate 27, fig. 1), re- 

 produced from a photograph taken in 1916, gives an imperfect view of the con- 

 torted beds. 



The cliffs reveal considerable diversity in the direction in which the con- 

 torted beds are overturned. Many small folds in the upper part of the section 

 display what appears to be overthrusting to the south or to the west. 



As the corrugated surface of the island truncates all the formations exposed 



