292. _ Scientific Intelligence. 
Tr; 
inadequate must be the conceptions of this force which we derive from 
viewing a stream at low water. 
. This rise in the Kangaroo Grounds is an index of what takes place 
every few years over the whole country. Our surprise at the amount 
of degradation subsides before such facts; and we rather wonder that 
sandstones so soft and fragile, which have been exposed probably from 
the Oolitic period, still cover the surface to so great an extent as they 
do at the present time. 
Mr. Darwin derives his principal argument against the hypothesis of : 
denudation from the forms of the valleys,—their width, extent and rami- ‘ 
fications, and yet narrow embouchures. But we find on consideration 
that this form is a necessary result of the mode of denudation under ‘i 
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has also been explained. The same cause should produce a like effect 
in Australia. Though it be a repetition, we add in this place a brief 
explanation of the process. stream, in making a descent of two or $ 
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finally become a series of cascades, or, as it happens at times in the 
Pacific, it may be reduced mostly to a single cascade of a thousand 
feet or more. 
The progress of this change may be better understood from the a 
given. 
' in Nabe Lonnie On the Transport of Erratic Blocks, Trans. Camb, Phil. Boc., vill, 
) pe S21. 
_ | p. 879 of this Report; also this volume, p. 57. 
