146 



CAPE COD GEOLOGY 



DISTRIBUTION 



Most of the Cretaceous beds are found in the western morainal area. From 

 Gay Head northeastward nearly to North Tisbury beds of Cretaceous clay 

 are exposed at many places, especially along the valley traversed by the North 

 Road. Some Cretaceous beds are exposed north of this valley, in the Indian 

 Hill region, beyond which none are seen except at a place near Norton Point, 

 where a large clay pit reveals them again. In nearly all this western area they 

 are covered by Pleistocene deposits. Cretaceous beds are not found above sea 

 level east of Chappaquonsett Pond. 



GAY HEAD 



As has already been noted, the largest exposures of beds of Cretaceous clay 

 are in the Gay Head cliffs (Plate 19, fig. 2), where they may be seen in a section 

 over a mile long. Here may be found the whole series so far as it is known, 

 beginning with the beds of lignite, upon which lie the beds of clay and white 

 kaolin sand. The section has been gullied considerably and presents much the 

 same form as a cliff in a badland region. The colors of the beds here are strik- 

 ingly brilliant. Upon the Upper Cretaceous clay lie the Miocene greensand and 

 some Pliocene sand, which is in turn overlain by Pleistocene deposits. The 

 thickness of the Cretaceous beds exposed here is exceedingly difficult to estimate 

 on account of complicated folding and overthrusting, but it probably nowhere 

 exceeds 100 feet. 



CLAY PIT NEAR MENEMSHA POND 



The nearest good exposure of Cretaceous beds east of the Gay Head cliffs 

 is in an old clay pit half a mile west of the northwest corner of Menemsha Pond. 

 This pit, one of the largest on the island exposes white kaolin sand and some red 

 clay. The sand is overlain by the Montauk till. The red clay, which flanks the 

 white sand on the northeast, lies below the Montauk till, as if it had been 

 dragged up by the ice. The white sand exposed in this pit forms a bed about 

 20 feet thick. It is cross-bedded and very gently warped into an anticline 

 having an axis extending east and west. 



MENEMSHA CREEK 



About a quarter of a mile east of Menemsha Creek, in a road cut on the 

 north side of the North Road where it descends a steep hill east of the creek, 

 there is a small exposure of Cretaceous white kaolin sand over clay. Above it 

 is "Wisconsin till. 



