president’s ADDRESS SECTION C. 
81 
I venture to think, is not the case. The erratic appears to be still 
firmly imbedded in the glacial strata, and the dip is therefore, on this 
supposition, original. On this hypothesis the grooves were scored on 
its surface by ice passing over it subsequent to the time of its 
becoming imbedded in the mudstone. Bearing ~W. 40° S. from “ The 
Stranger,” and seventeen yards distant, is another erratic, composed of 
dark greenish-grey quartzite. The lie of its longest axis is N. 25° W., 
and the trend of its grooves is in the same direction. As regards the 
parent rocks, from which these erratics may have been derived, Mr. 
Dunn states (op. cit ., p. 3) — “ Among the boulders, Ac., many are 
recognisable as derived from the sandstone aud conglomerate beds of 
Devonian age, such as occur in Gippsland and again (op. cit., p. 4) 
— “ Bocks similar to the Upper Silurian, and to the old jaspery beds 
of Maclvor Rauge, are common in the conglomerate, but it does not 
follow that even they are of local origin ; hut many of the granites, 
Ac., are not known in Victoria, and may have been transported for 
enormous distances.” Mr. A. W. Ho wit t, in a letter to me on the 
subject of these erratics, states — “ I was, however, struck by the 
appearance of the boulders, pebbles, Ac, at Derrinal as being quite, 
as a collection, unknown to me from any part of Victoria nearer than 
the mountains of North Gippsland.” The Maclvor range lies over 
twenty miles to the S.E. of Derrinal, and North Gippsland is from 
120 to 150 miles to the E.S.E. 
It appeared to me probable that the material had been brought 
through the low gap between Mount Alexander and Mount Macedon. 
Some of the granite composing the erratics near Derrinal appeared 
to me to closely resemble the Hareourt granite, which occurs in 
situ twenty miles to the W.SAV. At u Dunn’s Rock,” near Derrinal, 
the surface of the Lower Silurian sandstone has been planed down 
and strongly furrowed in a direction N. 7° W. A careful examination 
of this rock led me to the conclusion that the ice which had 
caused the grooving had probably moved from the south, as the sand- 
stone bed, which there forms the apex of an anticlinal curve, has 
been very strongly abraded at the southern end of its outcrop. The 
greatest altitude attained by the glacial conglomerate is stated by Mr. 
Dunn to be 700 feet above sea-level, and it must descend to at least 
300 or 400 feet lower (f Dunn)* The elevation of Dunn’s Rock is 
shown on his section as about 750 feet above the sea. A bed of 
sandstone, 60 to 70 feet thick, is inters tratified with the boulder- 
bearing mudstone. 
C. — Hallett's Cove , near Adelaide. 
As a detailed account of evidences of glacial action at this spot 
is given in the Report of the Glacial Committee of this Association, 
a brief summary will here suffice. Hallett’s Cove is distant about 
fifteen miles S.S.W. from Adelaide. The chief formations represented 
there are — (1) Pre -Cambrian, (2) the glacial beds of Post- Carboniferous 
and Pre-Miocene age, (3) Miocene marine beds capped by non- 
fossiliferous clays. 
A striated pavement of archsean rock extends for at least a mile 
along the coast, dipping below sea-level, and extending to over 100 
feet above the sea. The grooves trend chiefly nearly due N. and 
F 
