222 
^lAiTLiVND . — IVcslern Ausivalian Geology. 
The Western Australian Pernu)-CarlH)iiiferous ^laeiation marks 
jierhaps one of the most im]H)rtaiit e]»isodes in tlie geological his- 
tory of th(> State. The Penno-rarhoniferous period combines many 
\aried asjtects; and bihng the gi’eatest ic<‘-age through -which the 
world has i)assed, it renders the geological details of al)Sorbiiig 
interest — u]>oii which niiicli still innnaius, and will always remain, 
to be done. 
Investigation and study of this refrigeration is one of more 
than mei'(^ local signihcam'.e, for it forms an i]n])ortant and integra.l 
jeirt of the glaciation of the Southern Hemisphere during this 
geological period. 
There is also its t'conoinic inpnirtance, for des])ite the fact 
that there is an extensive area of rocks l)elongijig to the Permo- 
(’arboniferous or (’bal-forniing Period in the North-West, Central, 
ami KimluM'ley t)ivisioiis, they have almost everywhere })roved to be 
<h‘stitute of coal. A large iportion of these divisions having been 
covered by a great ice-sheet during this ])articulav coal-forming 
p(‘riod funiish(‘s a ])ossible ex])lanation as to -why there are no 
c('al de]>osits, for ther(* was Jieither sufti;:ient vegetable growth lo 
])i'<i(lu--(' thi'in nor wei(' the geological conditions favourable fiu- 
their accuniiilation and preservation. While the AVestern Aus- 
tralian P('i'ino-( 'arboniferous glacial de])Osits owe their chief im- 
])ortance to ])ure-ly scientific considerations, they do, however, mark 
very iin]ioitant stratigrajhiical hoihzons which not only tend to 
make possible geological correlation over the Australian Continent, 
but permit com])arison between the Western Australian formations 
and those in other portions of the world. 
Des})ite the inter(‘st which the discoveries of the evidences or 
this im])ortaiit great ice-age in the State arouse, it is only ])ossiblc 
to deal this evening with the salient issues in an all too brief 
a maimer. 
Wherever the beds of the Permo-Carboniferous system of Wes- 
tern Australia have been examined they have been found to be 
divisible into (a) a lower, or mainly limestone series, and (b) an 
ii])per, or sandstone series, with, in the Irwin and Collie districts, 
some coal seams. The beds associated with the coal-bearing mem- 
bers of the system contain abundant representatives of a llora 
characterised by sev('ral s]>ecies of the fern-like plant, (Ao.s.sop- 
(cris. which has not only a wide distribution bnl is so abundant 
fliat some of the rocks are largely made up of its tongue-shaped 
and reticulately veined fronds. 
TIip limestone series contains a rich assemblage of marine 
fttssils, characterised by the fretpueiit occv;rrence of a large number 
of species of the brachiopod, Froductua. 
