80 
president’s ADDRESS — SECTION C. 
The pavement, which was there composed entirely of soft clay 
slate, has weathered away for several feet inwards from the face of 
the cliff, so as to leave a space of a few inches between its weathered 
surface and the base of the overlying glacial beds. The under surface 
of the latter has preserved exquisitely the casts of the grooves, 
furrows, and even delicate strife with which the surface of the Silurian 
slates were once covered. The observer cannot fail to be specially 
struck by the remarkable freshness of the appearance of the strife and 
grooves on the included boulders in the glacial beds, as well as on the 
glaciated pavements. Hand specimens of either might easily be 
mistaken for examples of glaciated rocks of Pleistocene age from 
Europe or America, and yet it is certain that the date of this Australian 
glaciation dates at least as far hack as the commencement of the 
Mesozoic era, and probably the close of the Palaeozoic. 
Erratics ancl Boulders . — These are composed of whitish, to 
greenish-grey, red, and brown quartzite, felspathic quartzite, quartz- 
felsite, reddish quartz-grit, claystone, dark clay slate, mica-schist, 
granite, quartz, gneiss, &c. Daintree commented on the fact that 
(v. supra p. 01) the nearest spot to this locality where mica-schist 
occurred in situ , as far as he knew, was on a branch of the Grlenelg 
River, which is about 140 miles distant W. by N. He states that 
“the peculiar characters of some of the granites are unknown in 
Victoria.” Mr. E. J. Dunn (v. supra , p. 72) concludes that much of 
the material — [i.e. 9 in the Permo-Carboniferous glacial beds of Vic- 
toria — T.W.E.D.] — is foreign, and many of the rocks are not known 
to occur at present in this continent anywhere near Victoria. 
B. — Derrinah 
At Derrinal, near Heathcote, in Victoria, Dr. E. S. Pond kindly 
conducted me over some of the principal sections, and Mr. Hollings- 
worth exhibited to me a large collection of small erratics collected by 
him from the local glacial drifts. Although no fossils have as yet 
been found in the glacial beds at this locality, the lithological resem- 
blance to the Bacchus Marsh Beds is so strong that there can be little 
doubt, in my opinion, as to their contemporaneity. Here, as at 
Bacchus Marsh, are mudstones with boulders, conglomerates, and sand- 
stones, probably of Permo-Carboniferous age, and reposing on a 
glaciated pavement of Lower Silurian rocks. The glacial beds occupy 
a trough or valley in the Lower Silurian rocks, and have been traced 
by Mr. Dunn fifteen and a-half miles in a north and south direction 
with au extreme width of five miles. Large erratics are more common 
here than at Bacchus Marsh. The largest of these, “The Stranger,” a 
photograph of which, taken by me, is now exhibited, was estimated by 
Mr. E. J. Dunn to weigh about thirty tons. It is composed of coarse 
granite. Chi examining this erratic I noticed that part of the top 
was traversed by a groove 2 feet wide by 6 inches deep. The trend of 
this groove is about N. 10° AV\, and that of some other smaller grooves 
varies from N. 3° W. to N. 10° W. The lie of its longest axis is 
N.W. and S.E. 
The upper surface dips E. 30° S. at about 26°. As the surface 
slope of the ground is in the same direction, it might seem reasonable 
to suppose that the erratic had been gradually undermined by 
weathering, and had crept down the slope of the hill. Such, however, 
