THE PROBLEM OF ANTIQUITY OF MAN IN AUSTRALIA 37 
The other side is straight and smooth, apparently a natural 
cleavage surface, and the smaller end is bounded by two fractures. 
Weathering has dulled sharp edges. A few years later Brittlebank 
found two more artefacts in the same sub-basaltic gravel; one of 
these is the axe illustrated in Plate III, figs. 3 and 4. One-third 
of this axe protruded from the outcrop and the rest was embedded 
in tough sandy red clay which had to be picked away to free it. 
The other specimen, though less deeply embedded, was also firmly 
fixed in the clay. Both were found within a few yards of where 
the first was discovered. His letters to the Museum record that 
Brittlebank found the first artefact in an excavation made for 
the purpose of observing the effect produced by heat from the 
lava on the underlying gravelly clay. At about 1 ft. 8 in. or 2 ft. 
from the outcrop of this bed he found the implement in tough 
gravelly clay and almost in contact with the base of the lava flow. 
Since it differed in shape and size from the surrounding quartz 
pebbles, he examined it closely and, observing the chipped edge, he 
took it to water and washed away the adhering red sandy clay 
and small pebbles. He then saw that it was an implement made 
of hard slate. He was convinced that it could not have fallen 
through a fracture in the basalt to the position where he found 
it, nor have been placed there in post-basaltic times. Brittlebank 
being an experienced and accurate scientific observer and a sound 
geologist, his evidence must carry great weight. It has been 
suggested that the first-found implement may have been buried 
in recent times by surface material sliding down the slope of the 
hill (Mahony and others, 1933), but these authors did not know 
that Brittlebank found two other artefacts in the same gravel. 
Since the basalt was extruded, valleys several hundred feet deep 
have been cut through it into the underlying rocks, and the basalt 
where the artefact was found forms a small isolated plateau, 
locally known as The Island, since it is almost surrounded by the 
deep valleys of the Werribee River and Myrniong Creek. The 
area is close to the eastern margin of the Ballarat Plateau. The 
Island is about 1,200 ft. above sea level, and the adjoining Bacchus 
Marsh basin, through which the Werribee River flows, is nearly 
900 ft. lower and is only 5 miles distant as the crow flies. Brittle- 
bank made a geological map and section of the locality and marked 
on it the site where he found the first sub-basaltic implement 
(Plate IT): his manuscript map is in the National Museum of 
Victoria. 
The Werribee River is a puny stream. At Bacchus Marsh its 
drainage area is 115 sq. miles and its average discharge 250 gallons 
of water per second; in summer it usually ceases to flow. Between 
