president’s ADDRESS — SECTION C. 
79 
most places become too rotten to retain striae or grooves ; but traces 
of these are beautifully preserved in the form of casts on the under 
surface of the hard boulder beds, which have better resisted the 
tendency to decay. 
(8.) Lower Silurian (Ordovician). — Black slates and shales, with 
Graptolites and grey quartzites and felspatbic quartzites. These 
strata have been intruded by the granite mentioned above, and have 
been powerfully folded, their bedding planes in many places being 
vertical. The strike is N. 10° E., at the Werribee Gorge, but the 
general strike, as shown on Sweet and Brittlebank’s map, appears to 
be nearer N.E and S.W. Wherever the covering of glacial beds has 
been recently denuded or artificially removed from the surface of these 
strata, a grooved and striated pavement is exposed to view. These 
have been noticed by Messrs. Sweet and Brittlebank at intervals over 
the 130 square miles of country examined by them. 
Glaciated Pavements . — In the W erribee Gorge the surface of the 
glaciated pavement is very uneven, on a large scale presenting deep 
troughs bounded by slopes of over 70 degrees, or even by vertical 
cliffs, the troughs being separated from one another by rounded 
ridges rising to over 400 feet in places above the deepest portion of 
the pavement exposed in the troughs. Not only are the flatter 
portions of the pavement glaciated, but even the steep slopes are 
deeply grooved, striated, and furrowed. Where, as in the Werribee 
Gorge, the strata composing the pavements are made up of alternating 
beds of hard quartzites and soft clay shales, the surface somewhat 
resembles, though on a larger scale, a sheet of corrugated iron ; for 
the quartzite beds, having resisted abrasion better than the clay shales, 
project as rounded ridges from six inches to one foot wide, and 
separated from one another by grooves two to four inches wide, and 
of about the same depth. In this case the strife and grooves prove 
that the ice moved almost exactly parallel with the strike of the nearly 
vertical Silurian strata— the direction which would, of course, offer the 
greatest facilities for the unequal wearing of the hard and soft layers. 
Small hollows, presenting a rough or only slightly striated surface, 
showed where pieces of the pavement had been forced off by the 
moving ice, the fragments so dislodged beiug wedge-shaped, and it 
was noticeable that the thick end of the wedge invariably pointed to 
the south. The hollows occurred immediately to the north of joints 
crossing the Silurian strata in an east and west direction. Tho north 
side of these east and west joints was, therefore, evidently the stoss- 
seite. An examination of projecting points and ledges of the pavement 
confirmed the supposition that the ice moved here from south to 
north, as argued by Sweet and Brittlebank. The general trend of 
the grooves and strife is about from S. 12° W. to N. 12° E. At the 
lower end of the gorge the level of the glaciated pavement is about 
GOO feet above the sea, whereas in the Lerderberg flanges, to the east 
of Korkuperrimal Creek, it is (f Brittlebank) 1,400 feet above the sea. 
The distance of Werribee Gorge from the sea, at the nearest point, 
is about thirty miles. 
On the left bank of the Werribee Biver, opposite Daintree’s 
Cliff, are some wonderful examples of casts of the glaciated pavement 
taken by the glacial beds. 
