38 



CAPE COD GEOLOGY 



have been found at the stratigraphic horizon of the bed elsewhere in the cliffs 

 and farther east, in the Peaked Hill clay pits, as well as southeast of that point, 

 near the locality known as ' 'Long View." 



The paleontological importance of this small remnant of a deposit, which 

 consists chiefly of vein-quartz pebbles, chert pebbles, and transported teeth of 

 sharks and bones of cetaceans and higher mammals, without traces of such 

 feldspathic rocks as are found in the overlying Pleistocene glacial deposits, seems 

 to warrant its indication by a stratigraphic name. The name Aquinnah con- 

 glomerate is, therefore, here proposed, Aquinnah being a native Indian name for 

 Gay Head. 



The fossils found in the Aquinnah conglomerate have already been men- 

 tioned, except those found in certain black or at some places light-grayish chert 

 pebbles, waterworn and smoothed, and usually not more than an inch in their 

 largest diameter, for which no source has been found in the New England region. 

 The occurrence of fossils in these pebbles was announced by me in 1891, 1 

 but they were then erroneously referred to the Cambrian system. In a later note, 2 

 they were referred to some horizon as high as Silurian, on the authority of Wal- 

 cott, who had examined some of the material. The fossils found consist of small 

 species of bryozoa, tabulate corals, and pieces of crinoids. 



A chert pebble found by me in the cliffs at Gay Head in the summer of 1920 

 was submitted to E. 0. Ulrich, who recognized in it a branching species of the 

 tubulate coral Cladopora. He also recognized a longitudinal section of some 

 species of Aulopora, some irregular sections of some species of Aulopora, and some 

 irregular sections of a bifoliate Bryozoan of the genus Cystodiciya. He believes 

 that these fossils may belong to a horizon as high as the lower Middle Devonian 

 rather than to that of the Lower Devonian (Helderberg) , though he notes that 

 the New Scotland formation carries species comparable to those seen in the 

 specimen. He suggests that this fossiliferous chert pebble may have been brought 

 from the region near Hudson Bay or possibly from some place between the south- 

 ern end of the bay and the St. Lawrence valley. 3 The suggestion appears to favor 

 the idea that the pebbles were transported as stomach stones (gastroliths) by 



seals. 



FIRST STAGE OF GLACIATION 



The first events of the glacial epoch in this region are correlated with the 



Nebraskan glacial stage of the Mississippi Valley and with the supposedly con- 



1 Woodworth, J. B., Note on the occurrence of erratic Cambrian fossils in the Neocene gravels of 

 the island of Marthas Vineyard, Am. Geologist, 9, pp. 243-247, fig. 3, 1891. 



2 Woodworth, J. B. (with Shaler, N. S. and Foerste, Aug. F), Chert pebbles: Geology of the Narra- 

 gansett Basin, U. S. Geol. Survey Mon. 33, p. 113, 1899. 



3 Abstract of a letter of J. B. Woodworth dated September 30, 1920. 



