262 



Remarks on the principal Rocks 



colony the natural vegetation attains also its maximum luxu- 

 riance on those mountain ranges and gullies displaying the 

 older volcanic rocks ; thus on the eastern slopes of the Dan- 

 denong Mountains, and on some of the ranges of the Port 

 Otway District, which are thus geologically constituted, the 

 enormous dimensions and altitude of the ti^ees are not sur- 

 passed in any part of the globe. On the north-west coast of 

 New Holland, Sir Greorge Grrey particularly noticed during 

 his explorations there, the remarkable contrast between the 

 refreshing aspect of the vegetation on the few basaltic hills 

 he encountered, and that of the general surface of the coun- 

 try traversed by him. 



It would therefore, seem, from the experience of more than 

 half a century in New South Wales, that some of the soils 

 derived from the disintegration of volcanic rocks in Australia 

 are able to bear, without apparent exhaustion, an amount of 

 cropping that has, in America, been found by experience, 

 sufficient to wear out some of the most fertile soils there. 

 Soils displaying the extraordinary power of maintaining, 

 without artificial renovation, their fertility unimpared by 

 cropping, for a long series of years, are of very rare occur- 

 rence in Europe, although a few very remarkable instances 

 are recorded by Sprengel. 



Thus he states that a field near the village of Nebsteln, in 

 Germany, has been cultivated for the last one hundred and 

 sixty years without manure, and without being allowed to be 

 fallow, and yet has produced good crops. 



The analysis of soil formed by the disintegration of volcanic 

 rock analogous to that near Melbourne, has been found to be 

 as follows : — 



Silica 83-642 



Alumina ... ... ••. ••• 3'978 



Protoxide and Peroxide of Iron ... 5*312 



Peroxide of Manganese ... - . • • • 0-960 



Lime ... 1-976 



Magnesia ... ... ... ••• 0-650 



Potash in combination with Silica ... 0-080 



Soda in combination with Silica ... ^ ... 0'145 



Phosphoric Acid in combinatien with Lime 0-273 



Sulphuric ditto ditto ... a trace 



Humus, soluble in Alkaline Carbonates 1'270 



Chlorine ... ... a trace 



Hmnus ... ... ... ^-234 



Nitrogenous Matter ... ... 1*480 



The cultivation of wheat abstracts from the soil a larger 

 proportionate quantity of silicate of potash than most agri- 

 cultural products, and also demands an average quantity of 



