150 
AGE CHARACTERISTICS OF COALS 
There are ample proofs that the sea invaded many localities 
where coal was accumulating. The Lower Oolite of England has 
beds with great abundance of fragmentary marine shells. Liassic 
sandstones of Austria and Hungary include layers containing 
many forms of marine mollusks of littoral types. Ammonites are 
found at one locality, but that does not militate against the con¬ 
clusion that the water was shallow. If the shells be not drifted 
it shows that the genus could exist in shallow water. In any event, 
these deposits suggest that the areas in which they exist were 
lowlands close to the ocean level. 
Paleozoic coals require special consideration. In a great part 
of the areas where the deposits of Permo-Carbonic age are ex¬ 
posed the passage from the Triassic sequence is gradual; at most, 
the plane of union shows only petty discordance of stratification. 
In many extensive areas the succession of terranes is incomplete 
and some members are missing, so that the Triassic beds rest on 
any formation from the Archean to the Permian. In like manner 
when the rock sequence is complete the Permian beds may pass 
downward into the distinctly Carbonic strata so gradually that no 
definite boundary can be determined stratigraphically or by aid 
of changes in plant or animal remains. At times deposits assigned 
to the Permian rest on pre-Carbonic rocks, while in vast areas the 
succession is apparently conformable throughout. Lithological 
changes usually occur in the upper part of the section. At one 
time the presence of red coloration of the rocks was considered 
proof that the Permian beds had been reached. This opinion is 
not final, since in many regions red beds occur in distinctly Car¬ 
bonic strata. Frequently the basal portion of the Permian section 
contains conglomerates, holding pebbles which are striated seem¬ 
ingly by glacial action. 
The problems concerning the relations between Permian and 
Carbonic coal measures are vexatious to the last degree, since the 
testimony of stratigraphy, paleontology and paleobotany seems to 
be conflicting. In some cases the conflict is not real; but in others 
it is a fact and it can only be removed by revision of conceptions 
which have become laws because accepted for a long time. How¬ 
ever it is unnecessary to enter into discussion as to the propriety 
of regarding the Permian division as more than a subordinate 
section of the Carbonic succession. 
