26 
A. GIBB MAITLAND, F.G.S. : 
The palaeontological evidence would thus seem to point to 
there being in the Irwin River valley strata of both a Carbon- 
iferous and Permo-Carboniferous Age. 
Now it may be noticed that while such typical Carboni- 
ferous types, Produc.tus semireticulatus, Orthotetes crenistria, 
and Aulosteges occur in the Gascoyne beds associated with 
the Lyons Glacial Conglomerate, forms like Strophalosia 
Clarkei, Aviculopecten tenuicollis also occur, and in the 
Irwin River area the foraminifer Nubecularia Slephensi, 
which is characteristic of the Permo-Carboniferous of New 
South Wales, occurs in abundance. I am, therefore, after 
carefully considering the physical and palaeontological 
evidence, inclined to regard the strata containing the Lyons 
Glacial Conglomerate as being homotaxial with those of the 
Permo-Carboniferous of Eastern Australia. It this should 
ultimately prove to be correct it would seem that what 
may be called the purely Carboniferous types lingered on 
in Western Australia after they had become more or less 
extinct in the eastern margin of the Continent, and had been 
replaced in part by Permo-Carboniferous forms. The 
balance of evidence, therefore, seems to point to the glacial 
horizon in Western Australia being the equivalent of that 
in India and Eastern Australia and of Permo-Carboniferous 
Age. 
In South Africa is a well-marked glacial horizon, the 
Dwyka Conglomerate, occurring below beds which contain 
representatives of the Lower Gondwana Flora ( Glossopteris 
and Gangamopteris) . The ice which produced the Dwyka 
Conglomerate did not owe its origin to what may be called 
the Alpine type of glacier, but all the evidence points to 
the fact that it was : — 
" a broad continuous ice sheet which spread across 600 miles o£ 
country east and west and which advanced at least 500 miles pole- 
wards from its apparent source.” 
No undoubted marine deposits are anywhere associated 
with the Dwyka Conglomerate in South Africa, for the 
beds were deposited in large lakes, all the fossils found in 
which indicate freshwater forms. So far as any evidence 
at present available goes, it would seem that the South 
African glacial horizon was formed at the same geological 
period as that in India and Australia. 
In South America there are glacial beds which can be 
correlated with those of South Africa, India and Australia. 
In Brazil, near Minas, lat. 28*° south, is a glacial boulder 
bed, the Orleans Conglomerate, lying below the horizon 
of beds containing Glossopteris and Gangamopteris. The 
Orleans Conglomerate lies close to the base ot the Permo- 
Carboniferous Series as developed in that country. Near 
