312 
THE PHYSICAL GEOGRAPHY OF THE PAST. 
coincident with the laying down of masses of strata, which 
for various reasons they are agreed to consider as belonging 
to one geological age. 
The strata which are found succeeding the Carboniferous 
Rocks in upward succession are known as the Permian , and 
it is manifestly possible, by observing the position of these 
latter rocks relatively to the underlying Carboniferous, to 
ascertain if the great earth movements which produced the 
Pennine Anticlinal were anterior to the deposition of the 
Permian or subsequent. If, for instance, we find that the 
overlying Permian does not participate in the great folds of 
the underlying rock, or if we find great faults, which it can 
be shown have resulted from the Pennine upheaval, affecting 
the Carboniferous Rocks and not the overlying Permian, it is 
evident enough that the Pennine uplift must have taken place 
prior to the Permian epoch. 
Nearly twenty years ago Professor Hull came to the 
conclusion that the folding of the rocks in the Pennine Chain 
was of two distinct ages; whilst admitting that the east and 
west foldings were of pre-Permian age, he contended that 
the north and south folds must have been produced after the 
deposition of the Permian. The unsoundness of the latter 
opinion was shown not very long ago by Mr. E. Wilson and 
Mr. J. J. H. Teall, who instanced proof, that the north and 
south flexures must also be considered as pre-Permian. I 
am inclined to dwell upon this point for a moment, since I 
think our own neighbourhood affords an opportunity of 
testing the question, even better perhaps than some of the 
districts selected by the geologists I have named. 
I have stated that the north and south corrugations of the 
Pennine area may be traced southward into the region of our 
Aslibv Coalfield. Here we have also certain beds which I 
*/ 
have recently proved to be of Permian age, and which were 
evidently not laid down until all the great* north and south 
earth movements of the Carboniferous period had attained a 
maximum, thus leading irresistibly to the conclusion that the 
* It is too often assumed by geologists that the common arrange¬ 
ment in a disturbed district of folds and faults running at right angles 
to each other, forming what are known as a conjugate series, must 
have been produced by two distinct acts of lateral compression. It 
seems to me that the key to these phenomena is to be found in the 
beautiful experiments of Daubree on the influence of torsion and 
pressure upon the fracture of solid bodies, and that conjugate series 
both of faults and folds are best explained on the supposition of their 
contemporaneous origin. 
