198 Kendall: The Concealed Coalfields of Yorkshire , etc. 



This, I believe to be the foundation for the boundary adopted 

 by the Commission. 



Prof. Hull drew two lines upon the map which he presented, 

 one defining; the area within which the Coal Measures would be 

 found within 2,000 feet of the surface, and an outer one marking- 

 what he supposed to be the actual limits of the basin. In his 

 verbal evidence, however, Prof. Hull considerably enlarg^ed his 

 boundaries and expressed the opinion that Coal Measures would 

 be found at a depth of 4,000 feet 'as far east as the escarpment 

 of the chalk at the Humber.' This more optimistic view is 

 closely accordant with my own. 



The principle which has been my guide throug-hout this 

 inquiry is that which is chiefly associated in this country with 

 the name of Mr. Godwin Austen, whose great services to the 

 last Coal Commission are well known. 



Mr. Godwin Austen arg-ued that every undulation of the 

 strata whether trough-fold (syncline) or ridge-fold (anticline) 

 was based vertically upon, and was a repetition of a fold which 

 had affected older underlying rocks before the deposition of tlie 

 super-incumbent strata ; and that, too, despite any levelling off 

 to which the older rocks were subjected to atmospheric or 

 marine agents prior to the deposition of the later series. 



Without committing myself to a plenary and unqualified 

 acceptance of this doctrine I am quite prepared to admit its 

 general applicability, especially as in two cases, at least, I have 

 found evidence on the borders of the York, Derby, and 

 Nottingham Coalfield of a more convincing character than 

 Godwin Austen was able to adduce. 



The evidence of repetition of folding ('posthumous folding' 

 of Suess) may take the form not merely of an arching of the 

 rocks after deposition, but may manifest itself by the thinning 

 of beds as they approach the axis of the fold, and b}- planes of 

 erosion within the limits of a formation as well as by actual 

 gaps in the succession of the beds. Moreover, while some axes 

 of unrest present evidences of movements repeated again and 

 again through many successive periods, others exhibit unmis- 

 takable signs of the renewal of the folding movement after long 

 intervals of quiescence, or perhaps even of movements of the 

 opposite sign ; thus, -in the last case, a fold of the arch type 

 (anticline) may at some subsequent geological period sag down- 

 ward and receive a quite abnormal amount of deposition, and 

 later still may renew its arch-structure by the bending of the 

 newer rocks, 



N.itiiialist, 



