658 INDEX TO THE STRATIGEAPHY OF NORTH AMERICA. 



correlated on the evidence of the invertebrates they contain, with the Peedee sand of the Carolinas 

 and with the Monmouth formation of Maryland and New Jersey. 



The invertebrates present in that part of the Chattahoochee section lying below the beds 

 characterized by the presence of Exogyra costata Say and above the top of the Eutaw formation 

 indicate synchroneity with the upper marine invertebrate-bearing beds of the Black Creek 

 formation of the Carolinas; the few species of plants found in the same beds offer no evidence 

 in contradiction of this correlation. The invertebrates also point to synchroneity with aU but 

 the lowermost beds of the Matawan formation of Maryland and New Jersey. This portion 

 of the Chattahoochee section is believed to correspond approximately to the lower one-half of 

 the Selma chalk where the latter is most fuUy developed. No paleozoologic data have been 

 obtained for a direct comparison of the Eutaw formation with the Black Creek formation; how- 

 ever, the invertebrate fauna present in the upper part of the Chattahoochee representatives of the 

 Eutaw ("Blufftown marl") includes a considerable number of Black Creek species which do not 

 range up into the beds carrying Exogyra costata Say. On account of this close f aunal relationship 

 it is beheved that the Eutaw is represented in North Carolina by an undetermined portion of the 

 Black Creek formation lying immediately beneath the invertebrate-bearing beds of that forma- 

 tion. There is evidence for considering the upper part of the Eutaw (Tombigbee sand member) 

 as corresponding to the lowermost beds of the Matawan group (MerchantvUle clay) of New 

 Jersey. 



Fossil plants have been collected from the Chattahoochee representatives of the Eutaw 

 formation, and on the evidence thus furnished the beds have been correlated by E. W. Berry 

 with the Black Creek formation of the Carohnas, no particular horizon in that formation, however, 

 being designated, and with the Magothy formation of Maryland and New Jersey. The Tusca- 

 loosa formation in Alabama has furnished an extensive flora which Berry considers in part con- 

 temporaneous with the Black Creek flora, in this case likewise the reference being made to no 

 particular horizon in the Black Creek formation, and in part contemporaneous with the 

 Magothy formation. 



In this connection it may be stated that in an unpublished manuscript on the Creta- 

 ceous flora of South Carolina Berry admits the possibility of the Magothy flora having persisted 

 during the time of deposition of the Matawan equivalents in the Carolina and Chattahoochee 

 regions. 



The question of the correlation of the eastern Gulf Upper Cretaceous with the Cretaceous 

 of the western Gulf and western interior region is at the present time under investigatior . As 

 regards the age relations of the beds toward the lower part of the series the two classes of biologic 

 evidence, plant and animal, have led to certain differences of opinion between the students of each 

 class. Until further facts have been obtained and a closer comparison of the species in the two 

 regions has been, made, it seems inadvisable to attempt a. statement of exact correlation. As 

 regards that portion of the eastern Gulf Cretaceous, however, characterized by the presence of 

 Exogyra costata Say, there is general agreement that it corresponds approximately to the Navarro 

 formation of Texas and to an undetermined upper portion of the Montana group of the western 

 interior region. 



The Upper Cretaceous deposits present in South Carolina belong regionally with the deposits 

 of the same age in North Carolina, the former being the southward continuation of the latter. 

 The Carolina Upper Cretaceous is separated, geographically, from the corresponding Gulf Cre- 

 taceous deposits by a great overlap of Eocene strata. The two formational units recognizable 

 in North Carolina, the Black Creek and Peedee formations, are also easily distinguishable in 

 South Carolina. 



The Black Creek formation, the older of the divisions, received its name from Black Creek, 

 South Carolina, along whose banks and valley sides it is best exposed in this State. '^^* Better 

 exposures occur, however, in the bluffs of Cape Fear River, in Bladen County, N. C. 



The deposits typical of the formation consist of an estimated thickness of 500 to 700 feet 

 of irregularly bedded, laminated carbonaceous clays and thin laminae and lenses of sand, the 

 whole being more or less lignitic and pyritiferous. The sand lenses and laminae are slightly 



