528 GEOLOGY AND PETROGRAPHY Or CLAEENCETOWN-PATERSON DISTEICT^ ii., 



Permo-Carboniferous beds and the Kuttung Series, and the Bolwarra conglomerate, 

 alluvium being excluded from the map. In addition part of the outcrop of the 

 Mt. Gilmore toscanite is shown to the north. The two indicators, the Paterson 

 toscanite and Bolwarra conglomerate, are reliable datum lines to express the 

 structure in the Kuttung and Lower Marine Series respectively. The Kuttung 

 Series then shows clearly its disposition into two plunging anticlines and a plung- 

 ing syncline. The Permo-Carboniferous rocks, however, in the same horizontal 

 distance (14 miles) show three anticlines and two synclines and just off the left 

 hand margin of the map there is a very compressed syncline. The stratigraphical 

 interval between the two horizons is somewhere between three and four thousand 

 feet. From these facts it seems likely that, were the Permo-Carboniferous beds 

 laid down conformably upon the Kuttung tillites, then during the subsequent 

 diastrophism, some striking irregiilarities occurred in the behaviour of the several 

 units folded. The writer has studied Prof. David's map carefully and has 

 noticed that, further to the south, some other interesting divergences among 

 members of the Permian rocks are indicated, and, from a general knowledge of 

 the broad structural features of the area to the north-west, feels convinced that 

 examples of differential crumpling are evidenced. Thus, returning to the com- 

 parison between the area mapped by the writer and the Permo-Carboniferous 

 beds to the south, it is reasonably clear that the broad dome-like structure which 

 exists a little to the north of an east-west line from Paterson to Glenoak was 

 produced in the initial stages of folding and has acted as a relatively resistant 

 mass, being composed of hard lavas and tough tuffs and arkoses, against which 

 the Permo-Carboniferous beds, predominantly of comparatively soft strata, were 

 crumpled to a greater extent. This differential yielding would occur whatever 

 the original relationship between the two sets of rocks, and future work, it is 

 hoped, will help to solve this question. 



Phi/siograpJiy. 



The Paterson-Clarencetown area is only a portion of a large physiographic 

 unit, the Hunter River area. It is outside the scope of the present paper to 

 deal with the physiography of the latter area as a whole, but a detailed account 

 of the topography of the area mapped will be given below, a few brief features 

 of the Hunter River physiegi-aphy only being mentioned to form a setting for 

 the local discussion. 



The outcome of the work already done on the physiography of Eastern 

 New South Wales has been the recognition of the following major events. Some- 

 where in the middle or late Tertiary, Miocene or Pliocene, an extensive peneplain 

 was developed on which rose monadnocks often capped with "older" basalt, — 

 remnants from an older peneplain, possibly carved out during Cretaceous times. 

 When near a state of completion, the Tertiary peneplain experienced a slight 

 uplift and then a small subsidence, producing aggradation of the stream channels, 

 which were subsequently flooded with the "Newer" basalts; a slight uplift suc- 

 ceeding and also a period of erosion with the production of very broad valleys. 

 These events culminated in the Kosciusko uplift, with which the present cycle of 

 erosion was introduced. The Hunter River area, in common with the rest of 

 Eastern New South Wales, passed through all these vicissitudes, but during the 

 last, the grand uplift, sagged behind and was not raised to as gi-eat a height as 

 the neighbouring blocks. This, to some extent, is the reason why the Hunter 

 area has reached a high state of maturity so soon. The evidence for this dif- 

 ferential movement is to be found in the existence of faults on the margin of the 



