674 PROCEEDINGS OF THE BALTIMORE MEETING 



been equally prominent in North Carolina, though there we have less evidence 

 for determining their presence, while there is much more evidence of the 

 deposition of each formation upon an irregular erosion surface of earlier 

 formations. 



In the Coastal plain of Virginia and North Carolina the Tertiary strata have 

 been studied in detail only within the last few years, and as yet the divisions 

 recognized have not appeared in print. For this reason it is well to speak 

 briefly of the formations. 



Eocene Formation 



In Maryland the Eocene consists of two formations, the Aquia and the 

 Nanjemoy, which are, so far as determinations can be made, perfectly con- 

 formable, though resting upon the underlying marine Cretaceous which they 

 gradually overlap, and in southern Maryland and Virginia they extend over 

 the edges of the marine Cretaceous and come to rest upon the underlying 

 deposits of the Potomac group. The marine Cretaceous does not appear in 

 Virginia because of this overlapping cover of Eocene strata, though it makes 

 its reappearance in North Carolina, where the Eocene deposits have suffered 

 much erosion. The Eocene formations of Maryland extend across the Potomac 

 river, and reappear with the same lithologic and paleontologic characteristics 

 in Virginia, extending a number of miles to the eastward of the "fall line," 

 and extending southward as far as the James River drainage basin. From 

 that point southward the Eocene is covered up by later deposits of Miocene 

 and Pleistocene materials, and when the Roanoke and Tar River drainage 

 basins in North Carolina are reached we find that the Eocene is entirely 

 absent. In the valleys of those streams the Miocene is found everywhere rest- 

 ing directly on the underlying Cretaceous. In the southern part of North 

 Carolina the Eocene reappears, and there we find it again represented by two 

 formations, though these are distinctly different from the Eocene strata of 

 Virginia and Maryland. Lithologically the difference is very striking, in that 

 the glauconitic phase of the northern Coastal Plain Eocene is lacking, and in 

 its stead we have deposits of fine-grained calcareous marls or limestones. 

 Lithologically the North Carolina deposits belong to the Gulf phase rather 

 than the North Atlantic Coastal Plain type. Also in the fossil content there is 

 a marked difference between the North Carolina and the Virginia Eocene 

 formations, though as yet the paleontologic work has not progressed far 

 enough to definitely determine just how great a faunal gap exists between the 

 two series. The more recent age of the North Carolina Eocene, however, is 

 evident from the fossils. It seems probable that while deposition was going 

 on in Virginia, Maryland, and New Jersey during the Eocene period, North 

 Carolina remained above water because of the complete absence, so far as 

 known, of the Pamunkey series. In North Carolina the two Eocene formations 

 have received the names of Trent and Castle Hayne. The Trent formation is 

 developed best along the Trent river, though it occurs in patches over a large 

 part of the state. This formation contains fossils not recognized in any of the 

 Eocene formations of Virginia and Maryland, the most noticeable form being 

 the large species of Ostrea georgiana. This form is unknown north of North 

 Carolina, though it occurs farther south, and is found in great abundance at 

 the famous Eocene locality of Shell bluff, on Savannah river, a few miles below 



