276 R. H. CAMBAGE, 
may perhaps be accounted for through seeds having been 
carried across by the agency of birds, or it seems just 
possible both species may have extended right across before 
the mountains were uplifted to their present elevations in 
late Tertiary time. ”* 
In a paper on the flora from Bowral to the Wombeyan 
Caves I have previously referred to the possibility of H. 
albens having crossed the Main Divide before the final 
uplift.? 
The Cooma Geocol is a north and south gap with the 
lowest point on the Main Divide being upwards of 3,000: 
feet, and is therefore high enough to form a natural barrier, 
consequently there is little or no invasion of either the dry 
or moisture-loving floras from one side to the other. Much 
of this gap isa very expansive open plateau, and therefore 
the possibilities of plants crossing are less than in the case 
of the depression at Omeo. 
There is however a remarkably long valley down which 
the Murrumbidgee flows, northwards from near Cooma 
towards Canberra, and a fair number of western or warmth- 
loving plants find their way up this somewhat sheltered 
valley, and in this way reach elevations greater than those 
they attain anywhere else south of the latitude of Goulburn.. 
Sterculia diversifolia (Kurrajong) is an example of this, 
although it appears unable to face the cold of that portion. 
of the geocol on or near the Main Divide itself, 
The Lake George Geocol, though only alittle over 2,000 
feet above sea level is also a very broad plateau of plains 
and open forest, and in view of its southern latitude is. 
sufficiently elevated for the growth of the cold-loving plants. 
and therefore acts as a barrier between the moist east, 
1 “Geographical Unity of Eastern Australia,’ E. C. Andrews, B.A., this. 
Journal, Vol. xiv, p. 420, (1910). 
* Proc. Linn. Soc. N.S.Wales, Vol. xxx, p. 452, (1906). 
