40 CEE1ACEOUS DEPOSITS OF THE EASTERN GULF REGION. 



middle or lower portion of the Black Creek formation; they have been recognized paleonto- 

 logically in a well boring at Charleston, S. C, at depths of 1,974 to 2,007 feet. In New Jersey 

 they are represented by an undetermined upper portion of the Magothy formation. 



2. The Exogyra ponderosa zone, divisible into the Mortoniceras subzone and the remainder 

 of the zone (included between the Mortoniceras subzone and the base of the Exogyra costata 

 zone). 



The Mortoniceras subzone is represented in the Carolinas by a part of the Black Creek for- 

 mation immediately beneath the invertebrate-bearing beds forming the upper part of the forma- 

 tion, and in New Jersey probably by the Merchantville clay marl, the lowest formation of the 

 Matawan group. The remainder of the zone is represented in the Carolinas by the marine 

 invertebrate-be aring beds forming the upper part of the Black Creek formation, and in New 

 Jersey by the Matawan group exclusive of the basal formation or Merchantville clay marl. 



3. The Exogyra costata zone, represented in the Carolinas by the Peedee sand and in New 

 Jersey by the Monmouth group. 



Through a part of the eastern Gulf region the Liopistha protexta subzone is traceable near 

 the top of the Exogyra costata zone, and, locally in the region, in beds believed to be slightly 

 higher than those carrying the Liopistha protexta fauna, new fauna! elements are introduced in 

 association with species common to the Exogyra costata zone. The former has not been 

 differentiated in either the Carolinas or New Jersey Cretaceous; the latter is probably represented 

 in the Cretaceous beds exposed at and near Wilmington, N. C. 



