GLACIAL ACTION IN AUSTRALASIA. 
317 
sfoss-seite. In places the direction of grooving swings around to from 
S.E. to N.W., the probable reason for this being the opposition offered 
to the passage of the ice northwards by the closing in of the trough 
above referred to at its northern end, so that the ice was compelled to 
escape over the west edge of the trough (which is low, the east edge 
being high) ; and there being already a northerly component in the ice 
movement, the resultant movement, just at this spot, was north- 
westerly. 
(2.) Glacial Beds . — The junction of the Glacial Beds with the 
Archaean rocks is strongly uncon formable, as shown on sections A to 
B, and B to C, the Glacial Beds being almost horizontal, whereas the 
Archaean strata dip at about (1(5°. At a point about twenty-live 
chains S.S.W. from the northern extremity of the shore line, 
as shown on the plan accompanying this report, a slight contem- 
poraneous crumpling of the strata is observable, due possibly to the 
grounding of floating ice. The thickness of the Glacial Beds varies 
from 23 feet to over 100 feet. They attain an altitude of a little 
over 100 feet, and descend probably to a considerable depth below 
low- water level. 
The Glacial Beds are composed, in their upper position, of tough 
reddish-brown clay shales, alternating with soft yellowish sand- 
stones, and passing downwards into a jointed mudstone with glaciated 
boulders, and occasional lenticular patches of fine to coarse calcareous 
conglomerate. 
The upper portion of this formation is well stratified, and even 
laminated, but bedding is less distinct in the lower portion. The 
groundmass of the latter is chiefly a dark grey mudstone passing into 
argillaceous sandstone. The rock is fairly coherent, though less 
indurated than the Glacial Beds at Bacchus Marsh. The calcareous 
grits and conglomerates effervesce briskly in hydrochloric acid. At 
the first gully to the north of Black Point the Glacial Beds dip 
easterly at a low angle off the glaciated surface of the Arch scan rock. 
The outcrop on the beach, between high and low water marks, shows 
the beds to be jointed in directions between S. 30° to 50° E., and N. 
30° to 50° W., ar.d 8. 30° W. and N. 30° E. Jce-scratched boulders 
and pebbles are sparingly distributed through the higher portion of 
this deposit, where it immediately underlies the Miocene strata, but 
become more numerous at the lower levels, especially at the outcrop 
on the bench. In the lower portions of the Glacial Beds the boulders 
constitute from about one-tenth to about one-quarter of the whole 
bulk of the rock. They vary in size from pebbles an inch or so in 
diameter up to blocks weighing seven or eight tons, those which are 
between 1 inch and 1 foot in diameter being most common, in shape 
they are flattened oval or irregularly rounded or faceted. No absolutely 
angular fragments of rock were observed. Nearly all the quartz grains 
in the groundmass are intensely waterworn. The rounded boulders 
are for the most part scored with sets of parallel cuts from one- 
sixteenth to one-quarter of an inch in depth, and are covered with 
strongly-marked striae in parallel sets intersecting one another at 
various angles. Many of the harder boulders exhibit a dull polish. 
Most of them have their broadest surfaces parallel with the planes of 
bedding in the groundmass, but some of them are imbedded with 
their longer axes nearly vertical. 
