124 G. D. OSBORN] 



A PRELIMINARY EXAMINATION OF THE LATE 



PALEOZOIC FOLDING IN THE HUNTER RIVER 



DISTRICT, NEW SOUTH WALES. 



By G. D. Osborne, b.Sc 



With Plate VI. 



[Read before the Royal Society of N. 8. Wales, August 3, 1921.'] 



CONTENTS. 

 I. Introductory. 



II. General. 



(i) Principles Involved. 



(ii) Outline of the Work. 



III. Details of the Results. 



(i) The Shortening of the Crust, 

 (ii) The Height of the Folds, 

 (iii) The Depth of the Deformed Earth Block. 



IV. Preliminary Discussion of the Results. 



V. Results Obtained from the Amended Section, 

 (i) The Height of the Folds, 

 (ii) The Depth of the Folded Shell. 

 VI. 'General Discussion and Conclusion. 

 Bibliography. Explanation of Plate. 



I. Introductory. 

 During the Palaeozoic era various areas now constituting 

 parts of New South Wales were subjected to a number of 

 diastrophic cycles. Mountain building forces had their day 

 and ceased to be, time and again. The state of our know- 

 ledge regarding the actual details of these somewhat 

 rhythmic earth movements, however, is incomplete, but 

 from the pioneering geological work already done it is 

 sufficiently clear that many areas were involved in periods 

 of crustal compression, which were relatively rapid and 



