118 SUNKLANDS OF PORT PHILLIP BAY AND BASS STRAIT 
mentioned that the moving dunes on the King Bay shore have 
been formed since the occupation of the area by the white settlers, 
one of wiiom informed the author that they started to accumulate 
when the timber was thinned out in the sixties of last century; 
previous to this, the surface to high water mark was hard lime- 
stone. Ilis statement was verified by the exposure, after the sand 
had been redeposited by a gale, of an old fence and Banksias 
bearing on their branches partly calcified leaves. 
There is a similarity between the Nepean Peninsula flora and 
that of Deal Island, one of the Kent Group. Le Souef (1891) 
states that on the lower parts of it is thick, tussocky grass and 
on the higher ground a dense, short scrub, consisting principally 
of Melaleuca, ti-tree (Leptospermum) , sheoak, a small species of 
Eucalyptus, a pine identified as Callitris (a rainfall-deficiency 
genus), Banksia, Acacia, and others. This flora grows on the 
llelicidae Limestone, a member of a dune series, and the presence 
of Melaleuca suggests its affinity to the Nepean Peninsula flora, 
of which it may be a surviving remnant. 
The jieriods over which the various eustatic land bridges 
existed, more particularly those through King Island, were 
limited by the rate and amount of tectonic subsidence that was 
going on during the fall and rise of sea level. With the increase 
of subsidence towards the close of the Pleistocene, the life of the 
land bridges became successively shorter. Nature, states Ridley 
(1930), never allows an area, on which plants can grow, to remain 
bare for any appreciable length of time. Their appearance on a 
new soil is influenced mainly by the character of the soil or 
surface, its humidity or dryness, and the kinds of plants in the 
vicinity, and is not a criterion of the amount and class of seed 
which falls on the spot. Nevertheless, the xerophytic flora of Mud 
Islands in Port Phillip Bay, about 5 miles north of Sorrento, has 
been cither wind-borne or sea-borne. It grows on sand or shelly 
beds, the surface of which was submerged by the rise of sea level 
during the postglacial, and uncovered again by the recession now 
in progress ; it is about 3,000 years since the Mud Islands emerged. 
Summary 
Many attempts have been made to fix the times of the glacial 
stages of the Ice Age, and there is a diversity of estimates. There 
is, however, some agreement in fixing the time of the last glacial 
stage at about 18,000 years ago. This is so dated by Zeuner (1935), 
who bases his estimate on the solar radiation curve. The Yolande 
Glacial Stage of Tasmania is here taken to be the equivalent of 
