374 MESOZOIC FLORAS OF UNITED STATES. 



This is a much thicker and better section than could be measured 

 in the railroad cuttings near b}^, rising as high as anj^ of these and reach- 

 ing far below the raihpad bed. It is all included in what I aftenvards 

 called the Aquia Creek series (Brooke beds of Fontaine). 



Investigations in the District of Columbia, Maryland, and Virginia 

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

 tions of the Potomac beds to one another and to the ones l^elow and 

 above were somewhat thoroughl,y worked out. A number of localities 

 for fossil plants were discovered. Much grading of streets was iDeing 

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

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

 it occurs at all, is of course thin in that region, but contacts with the 

 underhdng Algonkian were often exposed. 



On NovemlDer 25, assisted by Mr. David White, I made the prin- 

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

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

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

 obtained a large number of specimens. We found the plant-bearing 

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

 ever, were found much higher. The cycads and conifers occurred 

 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 under the Atlantic border region of Mary- 

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

 seems not to have made personal investigations and confines himself 

 to a review of the literature. 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 been found. There 

 is, however, reason to suppose from lithological and stratigraphical 

 considerations that the beds forming the bluffs of the ,Cape Fear River 



« Correlation Papers, Cretaceous, by Charles A. AVliite: Bull. U. S. Geol. Surv. No. 82, 1891, pp. 88-92. 



