212 SPENCER MOORE [sepr. 1899 
range, he tells us, which is of granite, is capped by conglomerates 
doubtfully referred by Mr. F. T. Gregory to the Devonian age, but, 
perhaps, as suggested by Mr. Etheridge, really Mesozoic. Since Upper 
Devonian times there have always been land surfaces, at any rate in 
Eastern Australia, where there was partial interruption to absolute 
continuity during deposition of the Carboniferous rocks. The country 
presented the aspect of a vast archipelago while the extensive marine 
cretaceous beds occupying the low-level tracts of the interior were 
being deposited ; and not until the close of the Cretaceous period was 
the continent formed. These marine beds—the so-called Rolling 
Downs formation, of Lower Cretaceous age—were laid down in a com- 
paratively narrow sea connecting the Gulf of Carpentaria with the 
Great Australian Bight, and there is no evidence for the existence of 
interoceanic connection since that age, that is to say for the tertiary 
sea of Professor Duncan and Mr. Wallace. Following close upon the 
end of the Cretaceous epoch was another submergence during deposition 
of the older tertiary strata; but this did not involve so large an area, 
as these marine tertiary beds are not found more than fifty miles inland 
except round the Great Australian Bight and in the Murray Desert. 
After this, by unequal movements of depression, Central Australia 
became a lacustrine area, for the low-level deposits of this region are 
of lacustrine origin as their remains prove. Lacustrine conditions 
continued into Pliocene times, unless the formation known as the 
desert sandstone, which is of Plocene age, be eolian, as Mr. Tenison- 
Woods conceives. The extinct rivers, the circumscribed lacustrine 
basins marked by their coincident sand-beaches, and the remains of 
large herbivores prove the climate of Central Australia to have been, up 
till comparatively recent times, much moister than it is to-day. The 
subsequent history of the district has been one of gradually increasing 
desiccation. 
(To be continued.) 
