RELATIONSHIPS OF THE AUSTRALIAN CAINOZOIC SYSTEM. 
the same stratum to formations 
of different ages. 
The summary 
referred to is 
given below : — - 
M cCoy. 
Tate and Dennant. 
Ball and Pritchard 
Weriukooian 
( Pleistocene (Tate) } p 
(Pliocene (Dennant) j* liocene 
Kalimnan 
Older Pliocene 
Miocene 
Miocene 
Balcombian 
Oligocene 
Eocene 
Eocene 
Janjucian (now Miocene to Oli- 
Oligocene (?) (Tate) 
Eocene 
Janjukian) 
gocene 
Eocene 
Aldingan 
— 
Eocene (in part) 
(Eocene (in 
\ part) 
I ii Dry. Hall and Pritchard’s paper above referred to, the 
sequence given for the Australian Tertiary strata places the Janjukian 
at the base of the series. There is very strong evidence, however, 
in favour of the Balcombian being the oldest formation with marine 
fossils, and of an approximately equivalent age to the Upper 
Oligocene and Lower Miocene of Europe, North America, the West 
Indies, and Patagonia. In connexion with the last-named area, 
Ortmann* lately published an elaborate account of the fossils, and 
gave his conclusions as to the age of those beds. He also compared 
them with the Australian Tertiaries, agreeing almost entirely with 
the early views of McCoy. Dr. Ortmann based his conclusions upon 
a comparison of the fossil invertebrates with related forms from 
other localities and horizons in the Tertiaries ; and after giving the 
percentages of related fossils, goes on to say, “ We see a constant 
increase of the percentages from the Cretaceous to the Miocene, and 
then again quite a sudden decrease from Miocene to Recent.” 
As Dali and Ortmann have shown, some of the West Indian 
faunas used for purposes of comparison have been referred to the 
Oligocene, and this points to the Patagonian beds having a stronger 
affinity towards the Older Cainozoic than would otherwise appear 
from Ortmann’g previous calculations ; and accordingly the latter 
regards them more decidedly as Lower Miocene, f 
The Relative Values of the Percentage Method; and the 
Comparison of Typical Faunas, in Determining the 
Ages of the Australian Cainozoic Strata. 
When Sir Chas. Lyell formulated the method of judging the age 
of the various Tertiary beds of the London, Hampshire and Paris 
Basins by the percentage of the recent species of mollusca contained 
therein, he was dealing with a set of strata deposited under 
fairly constant conditions, and dominated by an entirely 
different geographical distribution of land and water from that 
which must have prevailed more or less throughout Tertiary times 
in southern Australia. Since Lyell’s time this once generally 
* Reports of tho Princeton University Expeditions to Patagonia, 1806-1899, vol. iv. , pt. 2, 
1902. Tertiary Invertebrates, pp. 48-332, pLs. xi-xxxix. 
t Op. supra cit., p. 297. 
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