106 
Lake Alexandrina to Overland Corner, and form the southern 
boundary of the Desert, which is more or less deliminated by the 
railway line from Murray Bridge to Tintinarra. Several deep 
wells on this route reveal at depths, corresponding with those at 
which the fossil beds were reached at Tareena and Mindarie, 
either the prevailing calciferous sandstone of the River Murray 
clitis, or an earlier, more or less argillaceous formation corres- 
ponding with the basal beds of the Aldinga section.* Whilst, 
further deep-seated Eocene strata extend into New South Wales, 
as proved by the occurrence of Trigonia semiundulata at a depth 
of 647 feet in the Arumpo bore, situate in the angle formed by 
the junction of the Darling aml Murray rivers.+ 
Tareena and Mindarie are situated at about fifty miles to the 
eastwood of the meridian of Overland Corner, which so far as. 
known demarks the eastern escarpment of the River Murray 
lateau, composed above the river-way of Eocene calciferous. 
p ; 4 
sandstone capped by Miocene sands and oyster-banks. Between 
Overland Corner and the confines of South Australian territory, 
Newer Tertiary lacustrine beds occupy the surface. Therefore, 
the fossiliferous beds beneath these at Tareena and Mindarie 
should be older than the River Murray Eocene-limestones (on the 
assumption that surface levels are approximately the same, and 
that the Eocene beds have little or no inclination, which I 
believe to be the case), or it may be that extensive erosion has. 
removed the Eocene strata, which have been replaced by a 
younger deposit, similar to the Tintinarra section, where a 
Pleistocene deposit (containing a great variety of recent species) 
fills a north and south trough in the Eocene beds to a depth 
beneath the surface of 154 feet.t The rejection of this latter 
explanation will involve the acceptance of a very prolonged — 
vertical range for a considerable number of species, and thus do. 
violence to the evidence of a restricted range for the vast majority 
of the Eocene mollusca. 
The opinion that our Pre-Miocene deposits are not all 
synchronous may be gathered from the “Correlation” papers 
contributed by myself in collaboration with Mr. Dennant, 
though as yet no scheme of succession had been submitted. 
Aided since by extended paleontological studies, I have ventured. 
to submit, perhaps prematurely, the following schedule showing 
the chronological sequence of the chief fossiliferous developments. 
*Clark, Tr. Roy. Soc., S. Aust., vol. XX.; p. 110, 1896; Tate, id., vol. 
XXII., p. 197, 1898. 
+zLtheridge, Records Geol. Surv., N.S.W., vol. III., p. 115, 1893. (On 
examination of the fossil I have confirmed the specific determination.— 
RT.) 
tTate, T., Roy. Soc., S.A., vol. XXII, p. 65, 1898. 
ae 
