BY H. I. JENSEN. 715 



observed both in New England and on the Liverpool Plains. 



C Basalt Knolls. — In the western interior of New South Wales, 

 smaller isolated basalt-areas are abundant, and are often so 

 extremely stony and bare of soil as to be useless for anything 

 but sheep-grazing. 



I). Basalt Ranges. — In the southern coastal districts of New- 

 South Wales basaltic ranges, like the Cambewarras, occasionally 

 occur. These are partly clad with forest, and partly with a 

 scrub somewhat less dense and luxuriant than the northern ones. 



^.Basaltic Bogs. — On the Southern Tablelands, and in the 

 Australian Alps in particular, there are many elevated basaltic 

 plains with a poorly developed drainage. In such places the soil 

 is cold, sour, and charged with mineral salts to such an extent 

 that forests cannot establish themselves. Sedges, grasses, and 

 reeds alone are able to exist. 



Having now described the different types of basalt-country, it 

 becomes necessary to define what factors control the vegetation 

 of each. 



A.Basalt Scrubs.* — These are all found in tropical or semi- 

 tropical, damp, or rainy climates. Rock-weathering is rapid and 

 penetrates deeply, because water charged with organic acids 

 sinks into the rock, and chemically attacks it. The soil is con- 

 sequently deep as well as fertile. The dense scrub prevents the 

 products of rock-decomposition from being rearranged in layers, 

 or mechanically transported to any extent, except on steep 

 slopes. The subsoil, therefore, is generally similar to the surface- 



* "These are, properly speaking, forests, tropical forests with the character 



of the Indian jungles I think it would be better if the term 



*' scrub " were not applied to these forests. They are so utterly different 

 from what is included under that name in other parts of the Colony, that 



jungle would be a far better expression In the true Australian 



scrub usually one or two species predominate, in fact almost exclude every 

 other. The jungle forests are of a much more mixed character. No one 



genus or even species gives its character to the forest In New 



South Wales, such forests are called 'Brushes.' " [Tenison- Woods, Botanical 

 Notes on Queensland, No. v.. The Forests or Scrubs. These Proceedings, 

 vii., pp.538-569, 1882(1883)]. 



