A MIOCENE FLORA FROM THE VIRGINIA COASTAL 
PEAIN? 
EDWARD W. BERRY 
Johns Hopkins University 
The later Tertiary of Europe is as remarkable for its extensive 
and representative floras, as is that of America for their absence, for 
with the exception of certain isolated florules of the Western Interior 
and Pacific coast region there are no known Miocene floras in America. 
The Atlantic coastal plain Miocene, or Chesapeake Group, appears 
to be made up entirely of marine deposits ‘carrying an abundant, 
chiefly molluscan fauna and furnishing but slight hints of the life 
which flourished along its shores. It has been correlated on the 
basis of its invertebrates by Dall and others with the Helvetian or 
Middle Miocene of Europe. The earliest member of the Chesapeake 
Group, the Calvert formation, is characterized in the Maryland- 
Virginia region by extensive beds of diatomaceous earth which rest 
with marked unconformity on the usually glauconitic sands of the 
Eocene or overlapping them to a notable extent in Virginia.’ 
While the Miocene of the world was in general a period of eleva- 
tion it would seem as if this elevation was greatest in eastern North 
America in the interval which preceded the deposition of the Chesa- 
peake Group, during which time the Eocene appears to have under- 
gone great denudation, since the comparative purity of the diatoma- 
ceous beds of the Calvert formation seems to have been due to the low- 
ness rather than to the remoteness of the adjacent mainland with the 
consequent lack of erosion. ‘This supposition is fully borne out by 
the evidence of the flora discussed in the following pages. 
Some years ago the Maryland Geological Survey discovered plant 
remains in the Calvert formation as exposed on Good Hope Hill 
which is situated in the District of Columbia just across the Anacostia 
t Published by permission of the Director of the U. S. Geological Survey. 
2 They of course rest on the older Cretaceous or the underlying crystallines in 
places where the Eocene is absent. 
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