80 THE KEILOR FOSSIL SKULL: GEOLOGICAL EVIDENCE OF ANTIQUITY 
the difference in level is 14 ft. The largest surviving fragment is 
about a mile long and a third of a mile wide and is situated at 
Braybrook near the western hill of Ascot Vale Gap. Its surface 
level is here 52 ft. above L.W.M. 
Maribyrnong Park Terrace at Dry Creek is 18 ft. lower than 
Keilor Terrace and at Chinaman’s Ford the difference is 35 ft. 
The largest remaining portion extends from a little above Ascot 
Vale Gap east and south of Quarry Hill and is about one mile by 
half a mile in area. Maribyrnong Park is situated on it. The 
surface level in this locality is 32 ft. above L.W.M. 
Below Ascot Vale Gap, the river has formed an extensive 
alluvial estuarine flat, the surface of which is about 10 ft. above 
L.W.M. and the adjacent tidal portion of the river. Flemington 
Racecourse is situated on it, and it may be named the Flemington 
Terrace. It merges into the Yarra Delta, the surface of which is 
about 8 ft. above L.W.M. 
The delta deposits are up to 50 ft. thick (Selwyn, 1854) and 
occupy a drowned valley (Hall, 1909). At. Coode Canal, Arca 
trapezium, a species now rare in Port Phillip Bay, is very abun- 
dant at 23 ft. below the surface (Lucas, 1887) and remains of 
Diprotodon were found at 35 ft. in estuarine sand in the Moonee 
Ponds Creek valley a mile north of the Footscray railway (Prit- 
chard, 1899). These organisms suggest some antiquity but do 
not prove the delta deposits to be Pleistocene in age. 
AGE OF THE TERRACES 
An outstanding feature of Pleistocene times is a series of 
eustatic changes in sea level. Relative to present sea level, the 
level fell during glacial phases and rose during interglacial phases. 
In Holocene times it fell 10-20 ft. owing to a slight fall in tempera- 
ture some thousands of years ago (Daly, 1934). 
Bearing these facts in mind, the following tentative correlations 
are made. 
The surfaces of the Flemington Terrace and the Yarra Delta 
were slightly below sea level immediately before the Holocene 
eustatic fall. 
The drowned valley occupied by Flemington Terrace and the 
Delta represents the eustatic fall in sea level during the most recent 
glacial phase, the Wiirm. 
Keilor, Braybrook and Maribyrnong Park Terraces represent 
the eustatic rise of sea level during the Riss-Wiirm interglacial 
phase. Their heights above sea level correspond to the 40-50 ft. 
raised beaches of northern Tasmania which Edwards (1941) corre- 
lated with the Riss-Wiirm interglacial phase. Their differences in 
