CHARACTER A] 



PROGRESS OF THE INVESTIGA' 



317 



The investigations have been conducted during the past five years 

 under the auspices of the United States Geological Survey and the state 

 surveys of New Jersey and Maryland. The boundaries of the forma- 

 tions have been platted upon the United States Geological Survey atlas 

 sheets, the areal mapping having been done upon the scale of one mile to 

 the inch throughout the entire district with the exception of Delaware 

 and the eastern shore of Maryland. 



Somewhat extensive changes have been made in the classification of 

 formations adopted by previous writers and some modifications in the 

 use of the formation names employed by the authors in earlier articles. 

 This has been the result of more complete knowledge of the formations, 

 based upon later work in Delaware and Maryland, and has shown that 

 certain divisions which are important in one area lose their identity and 

 become merged with contiguous members of the series in other areas, so 

 that they can no longer be stratigraphically or faunally separated. The 

 major divisions which have now been adopted are capable of application 

 to the deposits throughout the entire region from the Raritan to the Po- 

 tomac, and are the only ones which can be so employed with satisfactory 

 results. 



The Upper Cretaceous formations of New Jersey, Delaware, and Mary- 

 land here classified and mapped constitute a circumscribed province, 

 which is represented in a few isolated occurrences off the New England 

 coast and at one locality in Massachusetts. South of the Potomac the 

 strata become covered by a mantle of later deposits. The records of 

 certain well-borings point to the occurrence of Cretaceous deposits, in 

 eastern Virginia, but their character and extent have not been fully de- 

 termined. Similar deposits occur in surface exposures in the Carolinas, 

 but they have not as yet been sufficiently studied to show to what extent 

 they may be correlated with the formations of the northern Atlantic belt. 



Historical Sketch. 



The Cretaceous formations of the Atlantic Coastal plain have been the 

 subject of frequent discussions throughout the present century, while 

 scattered references to the district are found in the works of still earlier 

 date. 



The first contribution to the subject of Coastal Plain geology which is 

 worth y of special mention is found in the publications of Professor Peter 

 Kalm,* who was sent out to America in 1749 under the auspices of the 



* En Resa til Norra America, 8vo, 3 vols., i753~'6i, Stockholm. Translations in English by J. R. 

 Foster ; 1st ed., i77o-'7i ; 2d ed., 1772 ; another edition in J. Pinkerton's voyages, vol. 13, 1812 ; in 

 German by J. H. Murray, 1754- '64 ; in French by I,. W. Marchand, 1859. 



