EARLIER TERTIARY (EOCENE AND OLIGOCENE). 745 



those of lower and upper Oligocene,- Miocene, and Pliocene age, with perhaps some Pleistocene. 

 The portions of the "group " later than the upper Oligocene will be referred to in Chapter XVII 

 (pp. 806-813). The detailed tracing of the boundaries between the successive formations is 

 now in progress by G. C. Matson. 



I 17-18, J 18, K 18-19. NORTH CAROLINA TO MASSACITUSETTS, INCLUSIVE. 



The subjoined discussion of the Tertiary deposits of the northern Atlantic 

 Coastal Plain has been prepared by William B. Clark and is based on a briefer 

 statement ^^ covering this region. 



The Tertiary deposits of the Atlantic Coastal Plain overlie the Cretaceous formations 

 unconformably. They have been as a whole even less changed than the Cretaceous, although 

 they present much the same complexity, owing to the variation in the angle and direction of 

 tilting during the successive movements of the sea floor in Tertiary time. The sediments in 

 general form a succession of thin sheets which are inclined seaward so that successively later 

 formations are found toward the east. At no point do we find a continuous sequence of these 

 formations, a condition which must be regarded as marginal and due to the transgression and 

 retrogression of the sea along the coastal border, as continuous sedimentation must have been 

 going on over a considerable part of the continental shelf. 



The Tertiary formations have variously transgressed the underlying deposits and at many 

 points actually reach beyond them and rest directly on the crystalline rocks of the Piedmont 

 Plateau. Similarly later formations of the Tertiary have in many places transgressed the earlier, 

 and the latest formation provisionally referred to the Pliocene has been found over wide areas 

 resting on earlier Tertiary, Cretaceous, and crystalline rocks 'ahke. 



The northern Atlantic Coastal Plain contains deposits that are referred to the Eocene, 

 Miocene, and Pliocene epochs. The Eocene formations are best developed in Maryland and 

 Virginia, although Eocene deposits of moderate areal extent are also known in New Jersey and 

 North Carohna. The Miocene formations are most extensively developed in the drainage 

 basin of the Chesapeake Bay in Virginia and Maryland, but strata of that age also cover large 

 areas in North Carolina and New Jersey. The marine Phocene deposits are hmited so far as 

 known to North Carolina, although the Lafayette formation, of somewhat doubtful Pleistocene 

 or Pliocene age, covers extensive areas in North Carolina, Virginia, and Maryland. North of 

 these States only small remnants of the Lafayette have been found. 



Long Island and southern New England. — The Tertiary deposits of Long Island and southern 

 New England are confined so far as known at the present time to a few locahties on Long Island 

 and the islands off the Massachusetts coast. The scarcity of the exposures and characteristic 

 fossils has led to much doubt as to the age of the beds, although they have been generallj' 

 regarded as Miocene. The deposits have been studied cliiefly by Shaler,'^'*'^''"" Veatch,'" 

 Fuller, and Crosby. 



On Long Island small eroded remnants of supposed Miocene strata have been found over- 

 lying the Cretaceous, and certain sandy beds penetrated in deep well borings in the vicinity 

 of the city of Brooklyn have been thought to belong to the same horizon and have been 

 tentatively referred to the Beacon Hill formation of New Jersey. 



The residual sandy strata overlying the Cretaceous deposits at Gay Head, Marthas Vine- 

 yard, and containing a meager fauna of supposed Miocene age have also been referred to the 

 Miocene and may represent the same horizon. Similar deposits are also reported from Block 

 Island. 



New Jersey. — The Tertiary deposits of New Jersey comprise representatives of both the 

 Eocene and the Miocene. Some of the Miocene deposits are evidently unfossiliferous, so that 

 their position in the sequence of Miocene strata can not be clearly determined. Among those 

 who have studied and described these deposits may be mentioned Cook,'*' Whitfield,"^" 

 Clark,"='' "=' ""' '=' and Sahsbury.«" 



