10 
INAUGURAL ADDRESS. 
and in the upper part a bed of limestone, containing Ammonites and 
other mollusca of the Cretaceous series; and it was from this locality 
that the first proofs of the existence of the cretaceous formation in 
Australia were furnished to Professor McCoy. Closely associated 
with these limestones are ferruginous sandstones, containing casts of 
large accumulations of fragments of wood and vegetable debris , such 
as may be found after floods on the margins of rivers ; indicating an 
estuary system, where fresh and salt water alternated. 
AUSTRALIA AN ISLAND. 
The Mesozoic period closed with Australia reduced to the area of 
a large island on the east coast, and some small islands on the south- 
west and north-west of the present continent, and thus the connection 
with Papua was severed before the period when mammalian life was 
developed. 
A NEW ELEVATION. 
Early in the Tertiary period a new elevation of the land com- 
menced, but the rise was not attended by any great disturbance of 
the strata, as in almost every instance where the Upper Cretaceous 
rocks remain they are remarkable for their horizontal position. The 
elevation of the continent on this occasion was nearly equal in all 
parts. The ultimate altitude, at least 500 feet greater than at present, 
and the geographical effect was that Australia assumed nearly its 
present limits. 
FEATURES OF THE CONTINENT. 
The features of the continent at this time appear as high ranges 
on the east coast, and a nearly level tableland extending to the west 
coast, but the whole of the interior with a general incline towards 
Spencer’s Grulf. Short watercourses flowed direct to the sea, but far 
the greater area was drained by much longer streams towards Spencer’s 
Grulf, while a secondary series occupied the basin of the Murray and 
Darling Rivers. The climate evidently differed greatly from that 
now existent, as the denudations of the tableland removed tracts of 
country having an area of many hundreds of square miles, forming 
immense valleys bounded by flat-topped hills and ranges, representing 
the marginal remnants of the original surface. Enormous quantities 
of the finer-grained portions of the degraded shales must have been 
swept into the ocean by the rivers, but the coarser sands have been 
left in what is now the desert interior, where the wind drifts it into 
long steep ridges of bright red sand, having a northerly direction near 
the south coast, but spreading out like a fan to the east and west in 
the Northern interior. 
VALLEYS AND RIVER SYSTEMS. 
The interior rivers formed a grand feature of the country so long 
as the rainfall continued sufficiently copious to maintain their flow, 
but in the arid climate which now obtains it does not even compensate 
for the evaporation. The river channels have been nearly obliterated, 
