L, Lesquereux on the Coal Formations of N. America. 367 
Art, XXXIII.—On some Questions concerning the Coal Forma- 
tions of North America; by Leo LesQuerrux. 
(Continued from page 74.) 
_ Stratigraphical distribution of the Coal-flora. 
DETAILS concerning the stratigraphical distribution of the coal- 
ution of the strata of our coal-basins, that a section made in 
Western Illinois or Western Kentucky or in any part of the coal- 
fields of these States, will prove comparatively similar, (that is 
with some difference in the thickness of the strata,) to any sec- 
tion made in the coal-fields of Pennsylvania or of Ohio. This 
analogy of stratification has been fully established by a series 
° 
(2) 
B 
? 
pe) 
a | 
pS) 
=. 
< 
oO 
tT! 
oO 
re] 
oa 
° 
=} 
Mn 
3 
‘, 
° 
aS 
oD 
Qu 
o 
me 
> 
fas) 
3 
<q 
° 
— 
g, 
=a 
oO 
T| 
S 
oO 
my friend J. P. Lesley, in his excellent Manual of Coal. But 
it was not based on paleontological evidence and thus the con- 
temporaneousness of the juxtaposed strata was necessarily prob- 
lematical. On the contrary, by admitting the similarity of the 
flora of the coal-strata as a coéval mar a basis for 
juxtaposition of the strata, the result of the comparison of sec- 
ions gives evidence remarkable in a double point of view. 
First it shows, by juxtaposition of the coal strata of which the 
shales contain the same species of fossil plants, the uniformity 
of stratification in the whdle area of the coal-fields of the United - 
States; and secondly it proves that the distribution of the coal 
plants has followed the same developement, the same successive 
modification in the whole extent of the same coal-field. _ 
Though plants of carboniferous genera are found below the 
upper bed of the Archimedes or mountain limestone, as, appar- 
ently, no coal has been formed at this low station, I take as the 
of the true coal measures this Archimedes limestone, re- 
Sometimes its whole thickness, is a compound of coarse sand- 
Stone, shales and especially conglomerate, the last predominat- 
