334 C. A. SUSSMILCH AND W. G. STONE. 



to The Australasian Association for the Advancement of 

 Science. This was published in abstract only. In 1913 

 the same writer 1 gave a brief abstract of the geology of 

 the Jenolan District in his Introduction to the Geology of 

 New South Wales. 



C. Physiography. 

 The Jenolan Oaves occur in one of the valleys of the 

 western part of the Blue Mountain Tableland. A general 

 description of the physiography of this tableland has already 

 been published by the writer, 2 and a more detailed descrip- 

 tion is in course of preparation, so that only a brief account 

 is necessary here. 



That part of the Blue Mountain Tableland in which the 

 Jenolan Oaves occur has an altitude of from 3750 to 4000 

 feet, and its surface is a peneplain cut out of highly inclined 

 Palaeozoic strata and their associated igneous intrusives. 

 This peneplain is of Tertiary age and was elevated to its 

 present position at the close of the Tertiary Period (Kos- 

 ciusko Epoch). Rising above the general level of this 

 peneplain are residuals of the older tableland out of which 

 it has been cut; Mount Bindo is an example and is 4460 

 feet in altitude. 



Since the uplift of the tableland it has been deeply 

 dissected by stream action, and is now traversed by a series 

 of deep gorges; it is in one of these gorges, that of the 

 Jenolan River, that the Jenolan Oaves occur. In the Blue 

 Mountain Tableland as a whole, the present cycle of erosion 

 has reached early maturity, but in the Jenolan Oave Dis- 

 trict, which is close to the Main Divide, the valleys are 

 still in the youthful stage of their development and are 



1 An Introduction to the Geology of New South Wales, by C. A. Suss- 

 milch. Government Printer, Sydney, 1913, and 2nd Edition, Angus and 

 Robertson, 19 L4. 



2 Handbook for the New South Wales Meeting of the British Associ- 

 ation for the Advancement of Science, Sydney, 1914. The Central Table- 

 land of N.S. Wales, by C. A. Siissmilch, p. 495, (1914). 



