16 
GEOLOGV 
The strata of American Trias comprise valuable rocks for building a railroad. There are found 
in abundance sandstone, for embankments and bridges; dolomite, which produces an excellent hy- 
draulic lime; gypsum in incalculable quantities, for exportation; and, finally, salt. 
In order to verify still further the specific determinations of fossil plants made by Emmons, 1 placed 
in the hands of my friend, Professor Oswald Heer, a part of the collection of plants made by me in 
April 1849 at the coal-mines of Chesterfield county, Virginia, and also the descriptions and drawings 
published by Emmons, W. B. Rogers, Bunbury and Lyell; aud 1 give below the result which Mr. Heer 
was kind enough to send me. 
(TR.VXSLATION.) 
ZraicR , Julv 2.y’’ 1857. 
,*»*»*»_ The T<eniopteru magtiifolia \V. B. Rogers, is a species of the genus Stranfieriles , that differs by 
its large size from all the European species. 
Aeroslichiles oblongus Emmons. This species, at first considered by Bunbury and W. B. Rogers as the Pecop- 
leris WhUbyensis. is entirely dilferent. In the first place the form of the sari is not the same; then the American 
plant has a nervalio reliculata , or at least its secondary nerves are united to each other, while in the English plant 
the secondary nerves are digitated and dichotomous , and are never united laterally. 
Pecopteris falcalus Emmons. Resembles so much the Lauopleris germimns of Goeppert (See: Fossil Flora, livr. 
1. and 2. , pi. VI , fig. 8.) that it is very probable it belongs to this species. The Laccopleris germinans is found , 
according to Braun , in the Upper Keuper of Baireuth , Franconia. 
Pecopteris Carolinensis Emmons. This species belongs to the genus Gutbieria. 
Pecopteris (Aspidites) bullalus Bunbury. Resembles so much the Pecopteris StuUgartiensis of Brongniart, that 1 
do not hesitate to regard it as belonging to tlie same species. It is surprising that Bunbury has not recognized its 
great resemblance, at least, to the European species, so abundant in the Keuper of the environs of Stuttgart and 
Basle, and in Bavaria. 
Neuropteris linneefoUa Bunbury. Does not belong to the genus Nemopleris , but is a Cyclopteris smnlar to the 
Cyclopteris pachyrachis of the German Lias. 
#*„*»»************** 
Finally some species, such as: Plerozamites longifoHus , Equisetum columnare, Calamites arenaceus and Pecopteris 
StuUgartiensis, are fossils characterizing the Keuper of Germany and of the Swiss Jura. Some other species are 
simiiar to species found in Europe in the Keuper and Lias, although specifically entirely different; so that I am led 
to regard this coal flora of Chesterfield county, Virginia, and of Deep river, North Carolina, as contemporaneous 
egard 
with that of the Keuper of Wurtemberg 
rassic epoch. 
of Switzerland and of Bavaria; and I find nothing in it to indicate the Ju- 
Verv truly vours 
■ • OSWALD HEER. 
The authority of Professor Heer in fossil botany is like that of Agassiz for fossil fishes; and Lyell 
who until now (Sec: Supplement to the fifth edition of a manual of Elementary Geology, page 30; second 
edition, revised; London, 1857.) had regarded the strata of the Richmond coal-field in Virginia as be- 
longing to the lower part of the Jurassic series , has not hesitated to change his opinion in consequence 
of Heer’s determination; and during a visit to Zurich, in August 1857, he recognized these coal-fields 
of Virginia and North Carolina as of the age of the Keuper, and not liassic or oolitic as ho had previ- 
ouslv thought. Further, in a letter dated Florence, Tuscany, 5"' October 1857, Sir Charles Lyell says: 
« Another subject on which 1 am desirous of writing to you, is the Virginia Keuper. My brother-in-law, C. 
Bunbury , observes in a letter on this point , referring to his paper in the Quarterly Journal of the Geol. Soc. on the 
Riclmioiid plants, that he said; aThe formation might belong to the Jurassic (in which he included the Lias) or to 
the Triassic periods , and that it might with almost equal probability be referred to either)). 
((He. Bunburv, adds cat the time I wrote this the Basle and Baireuth beds were supposed to be Lias. The 
only specimen I saw of the supposed Pecopteris WhUbyensis was very imperfect indeed)))). 
As the Basic and Baireuth beds are recognized now by every geologist as belonging to the Keuper, 
it W'ill appear that Bunbury has never intended to put the Virginia coal field in the true Jurassic of England. 
So that we all agree to regard the Red Sandstone of Virginia and North Carolina as Keuper , and the bro- 
thers Rogers and James Hall stand alone in theiv opinion of Great Oolite, Inferior Oolite and Lias. 
