BY E. C. ANDREWS. 793 



to 4,300 feet above sea-level. These include the great flat-topped 

 masses east of Bathurst known as the Stony Ridges, the Clear 

 Creek Hills and Mount Horrible; while the Sunny Corner Hills, 

 Mounts Lambie, Walker, Binda and the Jenolan Hills represent 

 points rising to the same level, but more or less dome- or hummock- 

 shaped. 



Returning to a discussion of the 3,100 feet level, we find that 

 east of a line running north and south in the neighbourhood of 

 Mount Victoria there is a gradual decrease in slope to the sea, 

 varied only by local differences. Thus to Sydney, from Lawson 

 through Glenbrook, the general flat falls gradually to a height of 

 300 feet at the coast, broken, however, by the great valley of the 

 Nepean at Penrith and the famous raonoclinal fold and fault"^ 

 running north and south through Kurrajong Heights. To the 

 north and north-west of Sydney the general even easterly tilt 

 appears to be bent upwards so as to present a gentle glacis to 

 the metropolitan area. At Hornsby this slope has carried the 

 land to a height of 600 feet above sea-level; beyond this point 

 it spreads horizontally. Standing on the heights above the 

 Hawkesbury River, near Berowra, the surface appears as a plain, 

 surmounted by small flat-topped hills. Southwards from Sydney 

 the 300 feet level rises gently for 40 or 50 miles until the 2,200 

 feet level is attained, beyond which the surface spreads as a great 

 plain. Numerous small faults and folds will doubtless, hereafter, 

 be found associated with this bent surface. 



Throughout the Blue Mountains one finds tremendous gulches 

 or trenches w^inding among the plateaus. These are bordered by- 

 huge parapets or ramparts of sandstone and shale, as much as 

 1,500 feet high in places. All the clefts end in V-shaped niches, 

 into which waterfalls of great height precipitate themselves. 

 Frequently the bases of the canons are sunken 2,000 feet below 

 the level of the plateau. Under the sandstone ramparts comes a 

 steep slope of weaker material. 



* T. W. E. David, Journ. Proc. Roy. Soc. N.S. Wales, xxxvi., pp. 359-370. 



