374 MKbUZOlC FLORAS OF LMTFl) STATES. 



This is a niiich thicker and l)Otter section than could lie measured 

 in the railroad cuttings near by, rising as high as any of these and reach- 

 ing far below the railroad bed. It is all included in what I aftenvai-ds 

 called the Aquia Ci-eek series (Brooke beds of Fontaine). 



Investigations in the District of Columbia, Maryland, and Virginia 

 were continued through Julv and August, 1891, and the general rela- 



fe"- 



tions of the Potomac beds to one another and to the ones below and 

 above were somewhat thoroughly worked out. A nunil)er of localities 

 for fossil plants were discovered. Much grading of streets was l)eing 

 done to the iiorthwest of Washington and some fine sections were made 

 under circumstances that will never occur again. The Potomac, where 

 it occurs at all, is of coun-^e thin in that region, but contacts with the 

 imderlying Algonkian were often exposed. 



On November 25, assisted by Mr. David ^^'hite, I made the prin- 

 cipal collection of fossil plants from the Rosiers Bluff locality, discovered 

 on June 13. The bed is limited in range, being about 5 feet thick and 

 less than 150 feet long on the river front. We worked five hours and 

 obtained a large numl^er of specimens. We found the plant-bearing 

 stratum to be 4 or 5 feet thick and 30 or 40 yards long. A few, how- 

 ever, were found much higher. The cycads and conifers occiu'red 

 mainly in the lower and the dicotyledons in the higher portions. 



During the summer of 1891 the entire collection of fossil plants 

 used by Professor Fontaine in preparing his monograph was shipped 

 from the University of Virginia to Washington and installed in the 

 National Museum. 



Dr. C. A. White, in his correlation paper on the Cretaceous," 1891, 

 treats the Potomac formation vmder the Atlantic border region of Mary- 

 land, the District of Columbia, Virginia, and North Carolina. lie 

 seems not to have made personal investigations and confines himself 

 to a i-eview of the litei-ature. As regards the occurrence of the Older 

 Potomac in North Carolina, there still remain doubts, most of the Poto- 

 mac beds thus far discovered in that State belonging to the upper 

 division and no characteristic fossil plants have Ixhmi found. There 

 is, however, reason to suppose from lithological and stratigraphical 

 considerations that tlic beds forming the l)luffs of the Cape Fear River 



o Correlation Papers, Cretaceous, by Charles A. White: Bull. IT. S. Gpol. Siir%-. No. S2, 1891 , pp. 88-92. 



