BY W. G. WOOLNOUGH AND T. G. TAYLOR. 



549 



surrounding hills, consisting of Trias-Jura, Permo-Carboniferous 

 and Silurian rocks, rise to considerable heights above the level of 

 the gravel. 



The view from Ballanya Trig. Station is a very instructive one. 

 The country for miles around is of the nature of a peneplain 

 standing at 2,000 to 2,200 feet above sea-level. About ten or 

 fifteen miles away, to the N.W., W., and S.W., there appear 

 extensive areas of country rising to a height of 400 or 500 feet 

 higher than the general level of the surrounding country. These 

 have an almost absolutely level sky-line and very strongly suggest 

 the existence of an older peneplain. 



The course of the old river channel is fairly well defined from 

 its commencement at Digger's Creek to its junction with Joara- 



Shepherd TS 



Horizontal Sc 



Verh'ool Scale 



Fig. 2. — Profile section along the lowest portion of the Shoalhaven- 

 Woilondilly Divide. 



rnin Creek. The gap between Marulan and Shepherd Trigs, has 

 all the appearance of an old water gap (fig. 2). 



An examination of the bed of the present Wollondilly between 

 Carrick and Goulburn throws considerable light upon the struc- 

 ture of the old valley. The rocks composing the present gravels 

 are of the same types as those above described. The valley is 

 distinctly terraced; the present flood plain being from 20 to 25 

 feet above the water-level. An older flood plain exists at a level 

 of some 50 feet from the river bed. It consists of sandy alluvial 

 and rather fine gravel, very strikingly similar to the gravels at 

 the highest levels met with near Glenrock. In many of the 



