Barring-ton Tableland, information concerning which was given to the writer by 

 Mr. Sussmilch (c/. Osborne, 1921, p. 130). 



The peneplain of late Tertiary age on which the Newer basalts were ponred 

 occurs in remnants on Mt. Douglas at a height of 1,000 feet (neglecting the 

 thickness of basalt capping), and also, at a height of 1,130 feet, on Red Hill and 

 Mt. Johnstone. 



From what has already been said (p. 525) it is clear that a considerable 

 amount of erosion occurred in pre-Triassie times, and an actual peneplain may 

 have developed, upon which were deposited the Mesozoic sediments, but no 

 remnants of these have been found. 



The age of the heavy faulting has been shown to be pre-Miocene and in all 

 probability pre-Mesozoic, and this has physiographical interest. Had the heavy 

 faulting been connected with the Kosciusko uplift, modified fault scarps would 

 exist to-day, because the displacements are so large. But the topogTaphy is en- 

 tirely free, with one or two small exceptions, from direct regulation by these 

 meridional faults, and it goes to show how, in a cycle initiated by uplift and 

 accompanying heavy faulting, the alignment of the fault surfaces in an area 

 must have dominant influence on the initial stag'es of the resulting stream ar- 

 rangement. After the peneplanation of such an area, if subsequent elevation 

 without faulting occurs, the chief control is that of varying resistance of the 

 strata, faults and joints being of comparatively minor significance. This would 

 not hold in an area where the nature of the rocks was uniform. 



Stress has been laid on the importance of the government of topography by 

 the disposition of the strata in localities where the rocks are of varying com- 

 position {cf. Benson, 1920 and Browne, 1921). The area under consideration 

 here exemplifies this very convincingly. 



In the Clarencetown-Paterson area there are two large rivers, the Williams 

 and the Paterson, each fed by a number of tributaries which have dissected the 

 country to a well advanced stage. The contour map (Text-fig. 4) and the geo- 

 logical map (Plat« xxvi.) show many of the physiographic features. Section 

 P Q R S (Text -fig. 1) also illustrates the manner in which the two large rivers 

 have carved their valleys along the anticlinal arches, leaving the strong synclinal 

 structure to form a relatively resistant block. 



These two rivers, when considered throughout their whole length, are essen- 

 tially subsequent streams, as E. C. Andrews has pointed out (1903, p. 183), 

 flowing in a general north and south direction under the influence of the meri- 

 dional Tertiary faults and folds which occur along the Neweastle-Barrington 

 strip. The valleys of the two rivers can each be divided into two portions, in so 

 far as this area is concerned, the upper and lower portions respectively. The 

 dividing zone in each case is a relatively narrow neck where the valley walls close 

 in on account of the existence of a hard bar which has in all probability served, 

 as Dr. Browne suggested to the writer, as a temporary base-level to which height 

 the upper portion of the Valley was scooped out, involving a considerable amount 

 of erosion. 



Tlie upper portion of the valley of the Paterson consists of a broad stretch 

 of land at an elevation of from 100 to 150 feet, bordered on the western margin 

 by a high ridge which curves round in sympathy with the extent of the Paterson 

 River anticline. The case of the Williams is similar, the Gilmore ridge on the 

 east forming the marginal feature. These two ridges owe their existence to the 

 occurrence of a hard capping of toscanite which has protected them from erosion, 

 the Paterson toscanite in the ease of the Paterson River and the Mount Gilmore 

 toscanite in the other case. 



