11 HOB ART AND THE MIDLANDS 61 



Donatia, which is not a Composite at all, but one 

 of the Stylidiaceae. 



The top of Mount Wellington presents some 

 physical features of interest, especially in relation 

 to the weathering of the diabasic rock of which 

 it is composed. This rock whenever it forms the 

 face of an exposed cliff takes on the structure of 

 upright prismatic columns, which split longitudin- 

 ally ; the organ pipes on the face of Mount Welling- 

 ton turned towards Hobart are a fine instance of 

 this, but better still are the cliffs on the southern 

 face of Ben Lomond, and the wonderful fluted 

 columns of Cape Raoul on the east coast. Another 

 feature is the presence upon the plateau of Welling- 

 ton and Ben Lomond of extensive level fields of 

 large rounded boulders of diabase (Fig. 12), known 

 locally as ' potato ' or ' ploughed ' fields, which 

 do not support any soil or vegetation owing to the 

 gaps between the rocks, through which the rain 

 washes all the detritus away. These boulders 

 apparently represent the talus blocks which have 

 rolled off the once precipitous peaks of the moun- 

 tain, and as they themselves now lie nearly upon 

 the top of the mountain, with nothing but gently 

 sloping ridges above them, it is apparent what 

 an immense amount of denudation has. gone on 

 since first the diabase was exposed. 



During my rambles about the mountain I met 

 with many of the Tasmanian birds, and some 

 of the more characteristic of these may now 

 be mentioned. In wandering through the Aus- 



