312 NOTKS ON NATIVE FLORA OF NEW SOUTH WALES, VIL, 



view of the geological formation, is one of the most important 

 factors in limiting the growth of trees, for where basaltic areas 

 in New South Wales produce a wealth of vegetation, the rainfall 

 is high. Take Mount Wilson as an instance, with its noble 

 forest and dense undergrowth of luxuriant graceful treeferns, and 

 it is found to have an average annual rainfall of over 50 inches, 

 or quite 2^ times that of Cooma. The difference is slightly 

 greater at Kiama with its basaltic soil, and mean annual rainfall 

 of over 54 inches; and the same applies to places on the North 

 Coast. In spite of an annual rainfall of over 60 inches, the 

 basaltic hills around Kiandra are very sparsely timbered, the 

 extreme cold of a westerly aspect at an elevation approaching 

 5,000 feet, being too severe to admit of any robust growths. 

 The aspect of Monaro Plains is rather more westerly than easterly, 

 which is an important condition, for the warmer eastern aspect 

 of both Mount Wilson and Kiama, together, of course, with the 

 increased rainfall, has had a most important influence in pro- 

 ducing vastly greater forest-growths. 



The western atmosphere is dryer than the coastal; and, from 

 local enquiries made, it would appear that the winds of Monaro 

 come chiefly from the westward throughout the warmer months, 

 thus replacing the bleakness of winter by the dry conditions of 

 summer. 



Further, the rocks of this area are for the most part igneous, 

 of a basic character; even the granites have less acidity than 

 what are known as acid granites; and it has been noticed in 

 various parts of the State, that the acid (or siliceous) rocks are 

 much more prolific in species than the basic, under similar con- 

 ditions of moderate rainfall. On various parts of Monaro, where 

 a few forest trees exist, the occurrence may fairly be attributed 

 to the presence of rocks somewhat siliceous. Bushy Hill, which 

 is composed of a crushed quartz-porphyry, is an instance, though 

 this spot only supports a few Snow-gnmfi {fi!ucaly phis coriacea); 

 bub the appearance of even these, in contrast with the nakedness 

 of other elevations, has suggested the name of Bushy Hill for 

 the auriferous prominence just to the east of Cooma. 



