CAPE COD GEOLOGY 



43 



But I am confident from the association of species that the period of close intercommunica- 

 tion was Pliocene, because the fauna shows a milder climate than subsequently. This is true 

 all around the northern hemisphere. 



The fauna of the Gardiners clay, as shown by Fuller and Veatch, is that of 

 an interglacial stage that occurred long after the beginning of the Pleistocene 

 epoch. In the Long Island region, this clay has afforded the following species, 

 listed by Fuller: 1 



Anomia ephippium 

 Baccium obsoletum 

 Crepidula fornicata 

 Cyprina islandica 

 Mya arenaria 

 Mytilus edulis 



Modiola sp. 

 Nassa trivittata 

 Ostrea virginica 

 Purpura lapillus 

 Venus mercenaria 

 Solen ensis 



Shells of Pecten, fragments of an echinoderm, of Mullinia and Astarte, have 

 also been either reported or identified. 



The Jacob sand, which overlies the Gardiners clay, at least from Gay Head 

 westward, has yielded no fossils on Block Island or Marthas Vineyard. Fuller 2 

 refers the Sankaty Head section to this horizon and notes Sanderson Smith, 3 

 in 1867, collected a marine fauna from the Jacob sand on the east side of Gardiners 

 Island. 



The fauna of the Jacob sand in the western part of the New England Islands, 

 according to Sanderson Smith, is almost entirely molluscan, as follows : 



Anthozoa: 



A small coral 

 Gasteropoda: 



Tornatella punctostriata Adams 

 Bulla canallcula Gould 

 Fusus decemcostatus Say 

 Purpura lapillus Lam. 

 Nassa trivittata Say 

 Nassa vibex Say 

 Columbella unata Sowerby 

 Cheinnitzia interrupta Stimpson 

 Crepidula unguiformis Lam. 

 Crepidula fornicata Lam. 

 Natica duplicata Say 

 Natica heros or triseriataf 



Pelecypoda : 



Area transversa Say 

 Area pexata Say? 

 Ostrea borealis Lam. 

 Pecten islandicus Chemn. 

 Pecten magellanicus Lam. 

 Cardita borealis Conrad 

 Astarte sulcata Fleming 

 Lucina radula Gould? 

 Venus mercenaria Linn. 

 Mactra lateralis Say 

 Mya arenaria Linn. 



Crustacea : 



Balanus, fragment 



Fuller credits Veach with collecting from the same section the following ad- 

 ditional species, identified by Dall: 



Chrysodomus pygmaeus Gould Cyprina islandica Gmelin 



Astarte elliptica Brown Thracia conradi Couthouy 



1 U. S. Geol. Survey, Prof. Paper 82, pp. 104-106. 



2 Fuller, M. L., U. S. Geol. Survey Prof. Paper 82, pp. 113-114. 



3 Smith, Sanderson, Ann. N. Y. Lyceum Nat. Hist., 8, pp. 149-151, 1867. 



