GENERAL CONSIDERATIONS. 117 



This peculiarity surely has a meaning, and the question is, what is 



Interpretation of the ** ? l think ifc means that the uppermost mem- 

 above structure. ^er £ eac j 1 zone nas been preserved intact for 



such long distances, because the fold involving that zone, and the 

 reversed fault to the north of it, were the companions of the upheaval 

 of that zone from a condition of deposition ; that is to say, the upper- 

 most stratum had only just been deposited when it was folded, and 

 faulted, and so wrapped up with the older zone to the north that it 

 was preserved from sub-aerial denudation. 



For let us imagine a contrary case : let us suppose that the num- 

 mulitic strata, at the points where they are now seen to lie in thin 

 bands, were horizontal, or approximately so, and covered by an 

 immense thickness of Nahans and U. and M. Siwaliks before the 

 reversed folding and faulting took place. What would have hap- 

 pened in that case ? There is no such thing as a state of quiescence 

 in nature : either a rock is being added to by deposition or it is 

 being denuded away by erosion. Consequently, from the moment the 

 nummulitics with their horizontal burden of Nahan sandstone and U. 

 and M. Siwaliks rose from the level of deposition, they would begin 

 to be acted upon by rain and rivers. As they continued rising, they 

 would become cut into and sculptured in every direction by valleys 

 and gorges ; so that a geological map, if then drawn, would present 

 all those winding, circular, and ellipsoidal outcrops peculiar to a 

 country of horizontal strata. The result of a lengthy interval 

 between upheaval and folding would be an irregular patch-work of 

 strata, with innumerable outliers of younger formations upon older. 

 In some places the nummulitics would remain covered by a great 

 thickness of newer strata, in others they would be worn away 

 perhaps to nothing. Let us now suppose that a crushing sets in, 

 a lateral pressure of the mountain mass acting since the deposition 

 of the U. Siwaliks, and accompanied by reversed folds and fold-faults. 

 Could we then have that irregular patch-work of strata falling into 

 zones of formations of the regular kind I have described as actually 

 existing ? Could we then expect to see the long narrow outcrops of 



( 175 ) 



