Carboniferous Formation of Pennsylvania — Wasmuth. 313 
to the theory that the origin of synclinals and anticlinals is a 
natural consequence of active volcanoes, which has been produced 
by sinking of parts of the earth's crust. These theories 
demand inquiring into the state (plastic or hard) of the strata 
and coal beds at the time of the disturbance from their original 
horizontal position. From the facts developed, especially in 
coal mining, it is undoubted, that the rock and coal at the time 
of the disturbance from their original horizontal position, have 
been as hard as they are to-day. I might for convenience add, 
that geologically, each stratum has three extensions, two of 
which, (its length and breadth)'are predominant, while the third 
extension, the smallest one, is the thickness of the stratum. 
If, for instance, the distance a, 6, fig. 3, across a small 
synclinal of a coal ^<».3 
seam, is 30 feet, and ^ ^^ ^ ^ (j,?* 
its depth c, d is one 
foot, then the line a, c?, 
6, is about 30.4 feet 
long. If the coal bed in its horizontal position has been 5 feet 
thick, and if it had been in a plastic state at the time of the dis- 
turbance from its original horizontal position, then the substance 
30x5 must have been thinned out to about 30.4 feet long, and 
the present thickness of the coal seam in the synclinal should be 
about 4.93 feet; but out of 100 of such occurrences in the Pitts- 
burgh coal bed, in at least 90 occurrences the lamination and 
thickness are absolutely undisturbed and we find almost always 
that the coal bed has been disconnected by fracturing, at least 
once, in the length a, c?, h. It must be assumed that at the time 
of the disturbance referred to, the coal bed was overlaid l)y its 
present roof rock, and from the facts, of the origin of the 
synclinal in connection and the weight of the roof rock, the 
lamination and thickness of the seam have not been affected at 
all, but since there has resulted a fracturing of the coal and 
country rock (roof and floor),it must be concluded that the strata 
were hard. 
This will be proven by the facts; if for instance, the fracture 
appears in the neighborhood of the synclinal point fZ, sometimes 
the parts a, c?, and h, f?, of the strata are bent slightly doAvn- 
ward, toward the fracture without apparent dislocation; the 
fracture shows its original projections and it is tilled with 
