224 NEW SOUTH WALES. 



at their upper ends, often branch from the main 

 valleys and penetrate the sandstone platform ; on 

 the other hand, the platform often sends promon- 

 tories into the valleys, and even leaves in them 

 great, almost insulated, masses. To descend into 

 some of these valleys, it is necessary to go round 

 twenty miles ; and into others, the sui'veyors have 

 only lately peneti-ated, and the colonists have not 

 yet been able to drive in their cattle. But the 

 most remarkable feature in their structure is, that 

 although several miles wide at their heads, they 

 generally contract towai'ds their mouths to such a 

 degree as to become impassable. The surveyor- 

 general. Sir T. Mitchell,* endeavoured in vain, first 

 walking, and then by crawling between the great, 

 fallen fragments of sandstone, to ascend through 

 the gorge by which the river Grose joins the Ne- 

 pean ; yet the valley of the Grose in its upper part, 

 as I saw, forms a magnificent level basin some 

 miles in -width, and is on all sides sun'ounded by 

 cliffs, the summits of which are believed to be no- 

 where less than 3000 feet above the level of the 

 sea. When cattle are driven into the valley of the 

 Wolgan by a path (which I descended), partly 

 natural and partly made by the owner of the land, 

 they cannot escape ; for this valley is in every 

 other part surrounded by perpendicular cliffs, and 

 eight miles lower do%vn it contracts from an aver- 

 age width of half a mile to a mere chasm, impassa- 

 ble to man or beast. Sir T. Mitchell states that the 

 great valley of the Cox river, with all its branches, 

 contracts, where it unites with the Nepean, into a 

 gorge twenty-two hundred yards in width, and 



* Travels in Australia, vol. i., p. 154. I must express my ob- 

 ligation to Sir T. Mitchell for several interesting personal com- 

 munications on the subject of these great valleys of New South 

 Wales. . 



