480 PROCEKDINGS OF SECTION D. 



more particularly in the soutli. But in going northwards the cold of 

 the elevated New England plateau is tempered by the increasing warmth 

 of northern latitudes. 



The important question of aspect is practically decided by the 

 position of the main range. On its eastern side there is a combination 

 of warmth, moisture, and shelter which stimulates the growth of brush 

 or jungle. On the western side there is a reduced rainfall, less shelter 

 and moisture, and a full exposure to the chilling and drying influence 

 of westerly gales in winter or the scorching north-westerly winds of 

 summer. 



Apart from the typical eastern or western plants, those occurring 

 on the mountain area — which might be regarded as neutral ground — 

 often show a decided preference for aspect, of which the following are 

 a few examples. 



Eucalyptus coriacea, which extends throughout the entire lengta of 

 the State, and is practically restricted to the top of the mountains, 

 favors a westerly rather than an easterly aspect. It is growing around 

 Goulburn at elevations as low as 2,500ft., but away from easterly in- 

 fluence. It is absent from Blackheath and Mount Victoria, where the 

 altitude is 3,500ft. ; but, owing to the gentle slope from these places 

 towards the coast, the aspect may be regarded as more easterly than 

 westerly. The species may be found to the north of Clarence, however, 

 at about 20 miles northerly from Mount Victoria, and on the same 

 Triassic sandstone, but with a westerly aspect, though still on the 

 eastern watershed. It becomes common as soon as the western side 

 of the mountains is reached, near Lithgow, being distributed over 

 Permo-Carboniferous, Devonian, and granite formations, and extends 

 to the top of the Canoblas, near Orange, at over 4,000ft., where it is 

 subject to the full effect of westerly influence. Although it occurs on 

 Hawkesbury sandstone north of Clarence, it is not typical of such forma- 

 tion, and on the borderland of a westerly and easterly influence, such 

 as around Mount Victoria, E. coriacea would probably be found, if the 

 formation were granitic, not excessively acid. 



Another eucalyptus found along the main divide is E. dives, Schauer 

 (peppermint), and this also prefers a westerly aspect, though it shows 

 rather more partiality for sedimentary formation than E. coriacea does. 

 Although absent from Blackheath it may be found near Mount Victoria, 

 at Fairy Dell, and from this point westward becomes common until the 

 western slopes are reached just beyond Orange. This species does not, 

 so far as I am aware, cross to the northern side of the Hunter Valley, 

 and its absence from the New England plateau suggests that it may 

 possibly be newer than the valley itself. On the other hand, species 

 which are on both sides might therefore be regarded as older ; but the 

 whole question requires special investigation. E. dives is not the only 

 species which seems unable to cross this warm valley. 



E. pi/perrta, Sm. (Sydney peppermint) is often found in the mountain 

 division, but undoubtedly favors an easterly aspect. It continues from 

 Port Jackson up to Mount Victoria and Clarence, at an altitude of 

 3,G0Gft., but ceases when a decided westerly influence is encountered, 

 and prefers a sedimentary rather than an igneous formation. 



