136 G. D. OSBOKNE. 



strong crustal compression and the absence of thrust fault- 

 ing and resultant vulcanism. 



Therefore it may be stated, that although not exhibiting 

 the advanced stages of crumpling, the Lower Hunter 

 diastrophism is essentially of the thin-shell type. 



In the drawing in Plate VI an attempt has been made 

 to link up the adjacent earth blocks so as to obtain some 

 idea of the possible disposition of the shear plane, which 

 may be looked upon as separating the zone which par- 

 ticipated in the crumpling from the lower undisturbed 

 portion. Taking into consideration the fact that the section 

 under investigation is an incomplete one, and that the 

 folded structure is probably continued for some distance to 

 the west of Rix's Greek, and also probably extended to the 

 east of the present coastline, it is possible that the deeper 

 earth blocks which underlie the borders of the present 

 section are portions of huge wedge-shaped segments of the 

 earth's crust with whose margins alone we are dealing. 



In concluding this tentative discussion of the whole work 

 the chief feature which is the outcome of the investigation 

 may be stressed. This is that in the analysis of folding in 

 a region where heavy strike-faulting has occurred, the age 

 of which in relation to folding is uncertain, the examin- 

 ation is best made first upon the reconstruction of the folds 

 in the faulted positions, and then upon the restored section 

 with the strata in their pre-faulting disposition. The two 

 sets of results may then be compared and used to arrive at 

 the conception of the set of conditions obtaining during 

 the whole of the diastrophism and its resultant phases. 



The writer wishes to acknowledge his indebtedness to 

 Professor David, Professor Cotton, and Dr. A. B. Walkom 

 for advice in connection with this work. 



