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 
