GLACIAL COMMITTEE. 197 
Fibularia gregata, is seen to rest on the eroded surface of the 
glacial clay. This important section established beyond 
doubt, not only the pre-Eocene age of the glacial deposits, 
but, by inference, based on the stratigraphical unconformity 
of the two formations, a glacial age that must be antecedent 
to the Tertiary. This brings the South Australian ice-de 
posits one step nearer in time to the late Palzozoic or early 
Mesozoic glacial beds of Bacchus Marsh, in Victoria. 
Considering the important bearing of this evidence, it was 
gratifying to find it confirmed in a still more striking sec- 
tion, exposed in the cliffs of Point Turton, on the north 
coast. This section is remarkable as including four dis- 
tinct formations, with three planes of unconformability, as 
follows : — 
Feet. 
1. Recent: Travertine limestone of variable 
thickness, up to . 20 
2. Newer Tertiary: Clays ‘preserved it in eroded 
hollows of Eocene limestone; thickness, 
eth AO re wee Pay, aoe ve ke oo BAL AR eka AO 
3. Hocene: Compact limestone (worked for 
flux), variable up to . 35 
4. Glacial (pre-Tertiary) : “Till with included 
glaciated erratics, passes under sea-level ; 
exposed in face of cliff . se aetees 15 
The stones of the beach are ‘almost 
entirely the product of waste of boulder 
clay. 
The observations, briefly described in this report, have 
greatly extended the known occurrence of the pre-Tertiary 
glaciation of South Australia, and determine the valley 
of the Gulf of St. Vincent as one of the main channels of 
the glacial drift in a northerly direction. In those days, 
when the valley of the gulf was choked with ice, it was a 
much more important depression than it is to-day, for it 
has subsequently become choked with sediment at least 
2000 feet in thickness. A bore put down at Croydon, 
about two miles west of Adelaide, penetrated this thickness 
of Recent and Tertiary beds before reaching the older 
rocks. It is significant that the lower 500 feet of this 
section consists of unfossiliferous sands and clays, inferior 
to the Eocene beds. It is probable that they represent 
the glacial beds, which occupy the same stratigraphical re- 
lationship to the Eocene, at the southern end of the gulf, and 
which can be seen passing below sea-level at Hallett’s Cove, 
fifteen miles to the south of Adelaide. 
