79 
has been in detrital material to considerable depths. Compara- 
tively few, but still a few. cases have been noticed where water- 
worn gravels have been thrown out among the stuff sunk through. 
One very good instance is a well on the road from Rothsay to 
Field's Find, about half-way between the two so far as memory 
serves, wdiere the dump of the well showed a good deal of well 
worn shingly gravel. This well is sunk in the plain surrounding 
Lake Monger and merging into the bed of the latter by the 
characteristic imperceptible gradations previously referred to. 
From a good deal of scattered evidence of this sort, the writer 
has formed the conclusion that the surface of the bedrock below' the 
existing plains is generally somewhat variable in its relief, and that 
if the covering of detrital material conld bo imagined as removed, 
it would appear as a surface of gently undulating hills and hollows, 
such as might be expected of the surface of a peneplain reduced 
to approximate base level by subacrial agencies, and traversed by 
numerous watercourses of slight grade and consequent small 
depth of erosion of their valleys. But these surfaces have since 
been submerged luuler the system of large lakes of w*hich the ex- 
isting salt lakes are only the shrunken remnants, and their inequali- 
ties of relief have T)een filled up with lacustrine or marine drifts 
and sediments, and so reduced to the extremely complete state of 
planation in which they arc now found. While it is probably quite 
true that the main peneplanation of the bedrock as we now find it 
was due to suh-aerial erosion, it seems to me therefore that the 
final touches giving the landsca])c its existing iieculiar characteris- 
tics. w^ere given by submergence of the peneplain under consider- 
able bodies of w-ater. 
MATERIAL OF PLAINS. 
The materials composing the plains have always appeared to 
me very much more consi.stent with deposition as marine or lacus- 
trine sediments than as wind-borne material. Nothing is more 
characteristic of the goldfields plains than the way in which they 
are covered over immense areas wdth a coating of stones at sur- 
face. Very many of those stones arc oxide of iron pel)bles often 
showung concretionary structure and which may well have been 
formed almost in situ as ])isolitic growths. We know' that many 
of our typical laterite cappings both on the granite hills of the 
Darling Range, and on the sedimentary drifts of the coastal for- 
mation, appear to be formed first as small pisolitic concretions in 
the surface soil which are added to in course of lime as solutions 
carrying iron are draw'ii toward the surface by capillarity and the 
iron fixed by evaporation and further oxidation. In the same w'ay 
it is quite possible that many of the iron oxide pebbles on the gold- 
fields plains may have been formed very much where we now find 
them, and it may be pointed out that this explanation of their pre- 
sence would apply whether the superficial covering was formed 
from either wind-borne or water deposited sediments. If 
