254 REPORT OP THE AMERICAN COMMITTEE. 
Virginia, Kentucky and Tennessee, with most of Virginia, it 
contains a great mass of limestone. Its subdivisions beyond the 
Cincinnati arch are represented chiefly by limestone, a condition 
similar to that observed in the Eastern Border region of Nova 
Scotia and New Brunswick. 
The Pocono is persistent within the Appalachian area as far 
southward as the Tennessee border, and everywhere is a deposit 
of shale and sandstone carrying beds of coal. This is the char- 
acter of its deposits in the Eastern Border region. Within the 
Interior Basin the upper part is calcareous, Avhile the lower por- 
tion is shale or sandstone, and carbonaceous matter is present in 
small quantity. 
The relations of the lowest parts of the Marshall and Waverly 
are still somewhat uncertain, there appearing to be some reason 
for drawing a line at the Berea in Ohio, which would throw the 
lower beds of Ohio and the Oil Creek group in Pennsylvania 
into the Devonic. But the plant-remains of the Berea are more 
nearly related to Carbonic than to Devonic. 
THE EEGION BEYOND THE INTERIOR BASIN. 
That the conditions in the Rocky Mountains and beyond, are 
diiferent from those in the regions east from those mountains, has 
been mentioned already. Material for close comparison of the 
Carbonic of the Plateau Region with that of the Rocky Moun- 
tains and that of the Interior Basin is accumulating rapidly ; but 
it is not yet sufficient, so that nothing beyond a merely tentative 
statement can be given here. 
Within the Park Province of the Rocky Mountains the tipper 
Carbonic alone has been identified satisfactorily, the fossils being 
those which characterize the Coal Measures, or, at most, such as 
are common to both Upper and Lower Carbonic. The rocks are 
mostly sandstones, but limestones occur almost midway in the 
column and at the base. Ijimestone increases southward, so that 
in New Mexico two divisions are distinct, the lower containing 
much and the upper containing little limestone. Some of the 
lower limestones are crowded with Coal-Measures forms, which 
are present throughout the column, though associated near the 
top with an occasional type allied to Permian. The condition, 
in this respect, is very like that in the Appalachian region and 
