126 RESEARCH COMMITTEES. 
it is highly probable that glacial deposits extend in a northerly 
direction between Yankalilla and Myponga for a distance of 
nearly 10 miles, and were bounded in that direction by the lofty 
Sellicks Hill Range. The glaciation of the Cape Jervis Peninsula 
has now been demonstrated on two sides of the geographical 
triangle marked by Port Victor, Normanville, and Cape Jervis, 
and we may safely conclude that practically the whole of the 
country included within the area indicated has been visited by 
ice, and can be estimated at about 300 square miles. This 
estimate does not include the important outlier of glacial beds at 
Hallett’s Cove, 45 miles further north than Normanville. 
GENERAL CONSIDERATIONS. 
In our present limited knowledge of this great extinct ice-field 
it would be rash to express a definite opinion either as to the 
geological age of these deposits or the conditions under which the 
glacial phenomena occurred. We may affirm, however,— 
1. That the glaciation was on a scale of considerable nagnitude, 
as may be inferred from the following facts :— 
(a) The thickness of the Glacial Drift_—In the Back Valley 
borings have disclosed a deposit which there can be little 
doubt is of glacial origin, nearly 1,000 feet in thickness, 
To this must be added the-wash these beds have under- 
gone at the surface, which amounts apparently to over 
600 feet, giving a total of tnore than | ,200 feet as the 
original thickness of the glacial drift in the valleys 
referred to. Even at so great a distance from the centre 
of dispersion as Hallett’s Cove, there is a known thick- 
ness of over 100 feet above sea-level, with an unknown 
thickness below low-water mark, in the old valley now 
occupied by the Gulf St. Vincent. 
(b) The transporting power of the ice must have been great. 
What may be regarded as the great glacial highways,— 
the Inman and Bungala Valleys, Cape Jervis, and the 
depression of Gulf St. Vincent,—are in places crowded 
with very large erratics. There is a block moved by 
ice action at Hallett’s Cove, equal to the size of a small 
cottage, and on the beach below hundreds of travelled 
stones that would weigh over a ton each. 
2. As to the Geological Age, the capping of mottled clays resting 
on the drift at Cape Jervis (as at Hallett’s Cove), is suggestive of 
a Pre-Miocene age for the refrigeration of the Australian climate. 
The section at Cape Jervis, has not, however, been closely 
examined, and the evidence from that locality must be taken 
