BO Coal Basin of New South Wales. 
drainage from the summit level always fall, as I remarked 
near the Weather board into the head of these valleys, but 
into one side of these bay-like recesses.” Mr. Darwin’s own 
idea 1s, that what we see are the remains of enormous banks 
of sand, such as are now being formed in the West Indies 
and in the Red Sea, where it is said that the sea heaps 
masses of sand around rocks and islands, and in the most 
irregular forms. It is with great reluctance that I differ 
from a geologist so experienced as the author of the “Origin of 
Species ;”” but I do not think such an explanation as that 
given will satisfy one person out of a hundred who has seen 
the valleys in question. 3 
If I must venture on a hypothesis I should certainly 
refer what is witnessed to fluvial if not to atmospheric 
action. ‘The valleys, only on a grander scale, resemble the 
cullies which one sees cut into pliocene drift on the coast, 
more than anything else I am acquainted with. There is, 
or there was, previous to its being lately planted with fern 
trees, a gully in the Government House Reserve that 
looked like one of the Blue Mountain valleys seen through 
the wrong end of a telescope. This we know was the result 
of rain water, and it is only a question of time that would 
refer the larger valley to the came cause. 
But take an instance much more striking and conclusive, 
Near Keilor we have a valley nearly one hundred feet in 
depth cut through, not friable sandstone like that.of New 
South Wales, but indurate basalt, hard silicious rock, and 
compact silurian strata. All this has been done within a 
very limited period ; for the basalt in question is, if I mistake 
not, pliocine. All has been done, too, by a tiny stream, the — 
Deep Creek, for there are many circumstances which go to 
show that in the excavation of this particular valley waves 
and currents of the sea could have played no part. Take an 
instance, if possible, more striking still, the denudation of 
the basalt on the top of Mount Useful. This, too, is of 
recent origin, and yet was ever destruction of a rock and 
removal of the eroded material more complete and perfect ? 
Now the Blue Mountains bear evidence of being of 
immense antiquity, not only as a deposit, but as subse- 
quently upheaved dry land. If I might hazard an opinion 
I should certainly speak of them as being, with the excep- 
tion of our granitic chains, as the oldest land in Australia. 
The central portions of Victoria must have remained under 
water to a much later date, or how could the equivalent 
