CRETACEOUS FLORAS OF VIRGINIA AND NORTH CAROLINA 65? 



two formations when present in the same exposure and the consequent mixing 

 of collections. It was also occasioned by undue specific differentiations pro- 

 posed and the diagnostic value assigned to undeterminable fragments. 



Whereas several hundred species have been described from these beds, there 

 are probably not more than 150 to 250 species capable of recognition. For 

 example, Professor Fontaine describes 10 species of a coniferous genus, 

 Negeiopsis, from these deposits. A most careful revision of all the material 

 discloses but three species, in some specimens at least three of the former 

 specific types being shown on a single branch. The same author describes 42 

 species of the fern genus Thyrsopteris from this state. I have repeatedly gone 

 over this material, and while I have not decided just where to draw the lines, 

 there are only two distinct types represented in all the material on which these 

 42 species were based, their seeming diversity being due to individual variations 

 with all terms of the series present, coupled with the differences due to the 

 position on the fronds from which the particular specimens happened to come, 

 the foliage in question being that of a tree fern with large decompound fronds. 

 These are not exceptional cases, but the same is true of genera like Podoza- 

 mites, CladophleMs, Sequoia, Arthrotaxopsis, Sapindopsis, etcetera. 



The Upper Cretaceous of Virginia 



No deposits of Upper Cretaceous age have been recognized as outcropping in 

 the Virginia area, although the evidence obtained from deep-well borings in 

 the eastern part of the Coastal plain clearly shows the existence of strata of 

 this age beneath the Eocene. 



The Lower Cretaceous of North Carolina and its Correlation 



Entering North Carolina, we find the barnacles of the Lower Miocene sea 

 clothing the decayed granites of the Piedmont near Weldon. Eastward from 

 the fall line at this point the Roanoke river has trenched the Cretaceous sur- 

 face, and characteristic Lower Cretaceous materials are exposed beneath the 

 Miocene in the river bluffs for a score of miles. The next stream which 

 uncovers the Potomac beds is the Tar river, along w T hose banks low exposures 

 are seen for several miles above and below Tarboro overlain by Later Creta- 

 ceous deposits or Miocene, and the same is true of Contentnea creek. To the 

 southward of the Hatteras axis later conditions seem to have been different 

 from those which existed in northern North Carolina and Virginia, and the 

 Lower Cretaceous is present in force in the Upper Cape Fear basin for about 

 25 miles above and 14 miles below Fayetteville. 



The materials are similar to those from Maryland and Virginia. Semi- 

 lithifled arkosic coarse cross-bedded sands more or less argillaceous predomi- 

 nate. This formation has been named the Cape Fear formation by L. W. 

 Stephenson. 



This formation is to be correlated with the Patuxent formation of Maryland 

 and Virginia, since its lithological character is the same, its position on the 

 eastern margin of the Piedmont is the same, and it is overlain unconformably 

 by Upper Cretaceous deposits which correspond roughly to the Magothy and 

 Matawan formations of the Maryland region. The Patapsco formation which is 

 present in the northern Virginia area shows every evidence of pinching out 



