UPPEE PALEOZOIC (CARBONIc). 249 
SO very well marked in the Interior Basin and the Appalachian 
region, cannot be recognized with the same certainty at any but 
a few localities in and beyond the Rocky Mountains. 
THE UPPEE CARBONIC. 
This contains the Coal Measures, a series manifestly one 
throughout the Appalachian and the Interior Basin region, 
where it can be divided, partly on physical and partly on paleon- 
tological grounds, into three divisions; while in the Rocky 
Mountains and beyond, only two have been observed. The 
exact equivalence of any division in one region with a division 
in another can not be made out with entire satisfaction, as open 
sea prevailed westward from the Cincinnati arch, while the Ap- 
palachian area was an immense shallow gulf almost closed at the 
south by converging peninsulas. The marine fauna, therefore, 
is not of constant assistance — indeed it sometimes leads to con- 
tradictory results. The natural divisions for the United States 
east from the Rocky Mountains, appear to be Upper, Middle, 
and Lower Coal Measures. Respecting these there is a sub- 
stantial agreement in all communications referring to the Coal 
Measures, though there is some disagreement respecting lines of 
division. 
Upper Coal Measures. 
Synonyms and Local Subdivisions. 
Pennsylvania XIII. C C Upper Barren | Greene Group. 1 Per- 
in part. } ^^^' j Group. | Washington Group. J mian. 
Monongahela Series. |^^- j Upper Productive Group; Upper Produc- 
v tive Coal Group. 
Virginia and West Virginia XVI. ") ^^ ^ , ,, 
■vv i" Upper Coal Measures. 
Ohio. — Upper Coal Measures. 
_ ,. ( Merome Sandstone. 
I Upper Coal Measures. 
Illinois. } 
Tow I Upper Coal Measures. 
Kansas. ] 
Missouri f ^^^^o-Carbonic and Coal Measures in part. 
Western Regions. — Permo-Carbonic and Upper Carbonic in part. 
Nova Scotia. — Permo-Carbonic. 
New Brunswick.— Upper Coal Measures. 
The well-known Pittsburgh coal-bed has been taken as the 
base of this division for the Appalachian area. That bed has 
