XIX GREAT VALLEYS 467 



ascend through the gorge by which the river Grose joins the 

 Nepean ; 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 surrounded by cliffs, the summits of which are 

 believed to be nowhere 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 down it contracts from an average width of 

 half a mile, to a mere chasm, impassable 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 2200 yards in width, and about 1000 feet in depth. 

 Other similar cases might have been added. 



The first impression, on seeing the correspondence of the 

 horizontal strata on each side of these valleys and great 

 amphitheatrical depressions, is that they have been hollowed 

 out, like other valleys, by the action of water ; but when one 

 reflects on the enormous amount of stone which on this view 

 must have been removed through mere gorges or chasms, one 

 is led to ask whether these spaces may not have subsided. 

 But considering the form of the irregularly branching valleys, 

 and of the narrow promontories projecting into them from the 

 platforms, we are compelled to abandon this notion. To 

 attribute these hollows to the present alluvial action would be 

 preposterous ; nor does the drainage from the summit-level 

 always fall, as I remarked near the Weatherboard, into the 

 head of these valleys, but into one side of their baylike re- 

 cesses. Some of the inhabitants remarked to me that they 

 never viewed one of those baylike recesses, with the headlands 

 receding on both hands, without being struck with their 

 resemblance to a bold sea-coast. This is certainly the case ; 

 moreover, on the present coast of New South Wales, the 

 numerous, fine, widely-branching harbours, which are generally 

 connected with the sea by a narrow mouth worn through the 

 sandstone coast- cliffs, varying from one mile in width to a 

 quarter of a mile, present a likeness, though on a miniature 

 scale, to the great valleys of the interior. But then immediately 

 occurs the startling difficulty, why has the sea worn out these 



