THE PLEISTOCENE OR GLACIAL PERIOD 451 



ably the equivalent of the Low-level Columbia farther south, and this 

 name may well be given to the second subdivision of the original 

 Columbia. For this subdivision the name Wicomico has been used in 

 Maryland. To the youngest phase of the formation the name Cape 

 May J has been applied, from one of its typical localities. In Mary- 

 land this subdivision has been called the Talbot formation. 



Over all the preceding formations, Bridge ton, Pensauken, and 

 Cape May, and perhaps extending even beyond the oldest and highest 

 of them, there is a thin and discontinuous deposit of loam, which in 

 some places seems to represent a phase of deposition distinct from 

 all the preceding. Similar loam sometimes covers the glacial drift 

 of last-glacial age. Its interpretation is still an open question. 2 It 

 is very probable that different parts have originated in different ways. 

 In many places the loam has sufficient thickness to obscure the rela- 

 tions of the underlying formations. 



Stratigraphic relations. — The various members of the Columbia 

 series rest unconformably on inferior formations. On the Atlantic 

 Coast, the older divisions often rest on the Lafayette formation, and 

 often on terranes from which the Lafayette had been eroded before 

 the deposition of the Columbia series. 



Fossils. — The Columbia series rarely contains fossils. At a few 

 points, however, shells of fresh- water molluscs have been found in 

 the Pensauken but a few feet above the present sea-level. 3 Marine 

 shells have been found in gravels which are perhaps of Pensauken 

 age, on the east coast of New Jersey. Such evidence as the few fossils 

 afford, therefore, is against the marine origin of at least parts of the 

 formation. The Cape May formation, like the older Pleistocene for- 

 mations of the Atlantic Coast, is generally without fossils, but marine 

 shells have been found in it at a few points (southern New Jersey) 

 a few feet above sea-level, 4 and about Philadelphia marine diatoms 

 have been found in the loam which covers it, up to an altitude of 40 to 

 60 feet. 



1 Report of the State Geologist of N. J. for 1897, p. 20. 



2 See Report of State Geologist of N. J. for 1897, p. 20, and Vol. V, Glacial Geology 

 of N. J. 



3 Report of the State Geologist of N. J. for 1896, p. 205. 



4 Report of the State Geologist of N. J. for 1885, and Geology of Cape May County 

 1859. 



