DIVERSITY OF THE GLACIAL PERIOD 765 



Tobacco Lot Bay : 



Chrysodomus decemcostatus, Say. 

 C. pygmaeus, Gould. 

 Natica (Lunatia) heros, Say. 

 Astarte elliptica, Brown. 

 Pecten magellanicus, Gmelin. 

 Cyprina islandica, Gmelin. 

 Thracia conradi, Coutony. 



Dr. Dall remarks: "The material appears to be practically 

 identical from both localities, and to represent the fauna now 

 existing in the gulf of Maine or on the coast north of Cape Cod, 

 a little colder water being indicated than is now found south of 

 the cape." Smith' and Merrill^ have both published lists of fos- 

 sils which they collected at the Tobacco Lot Bay locality. 



These beds present all the characteristics described by Wood- 

 worth in the Sankaty beds farther east, and, as already indicated 

 by him, are to be so correlated. ^ 



Folding and erosion of Sa?ikaty beds. — Considerable time will 

 be required to completely work out the very complex system of 

 folds developed on this island, but the following points regard- 

 ing them are of interest. Involving as they do, preglacial, 

 glacial, and interglacial deposits, they are clearly of Pleistocene 

 age, and their irregularity is strongly suggestive of a glacial 

 origin. Near the center of the northeast shore a series of four 

 folds was worked out whose axis is north 20° west. A little 

 farther east, near Eastern Plain Point, there are three or four 

 sharp, partially overturned folds, whose axes are almost due 

 east and west. 



Manhasset deposits. — Although the similarity of the Manhasset 

 to the Tisbury beds* would lead us to expect them to appear on 

 Gardiners Island on the top of the eroded folds of the older 



'Sanderson Smith, "Notes of a Fost-Pliocene Deposit on Gardiners Island, 

 Suffolk County, New York," Annals of the New York Lyceum of Natural History, 

 Vol. VIII (1867), pp. 150, 151. 



= F. J. H. Merrill, "On the Geology of Long Island," Annals of the New 

 York Academy of Science, Vol. Ill (1886), pp. 354, 355. 



3 J. B. WooDWORTH, Seventeenth Annual Report {i?igb), U. S. Geological Survey, 

 Part I, p. 976. 



*Ibid., p. 977. 



