27 



three miles across. The soil covering the several formations 

 is everyAvhere a more or less sandy clay, rarely replaced by 

 pure sand, with this difference in the substratum, that the 

 loose limestone concretions on the newer ai*e replaced by a 

 solid travertine on the older formations, the respective rocks 

 only protruding at rare and wide intervals, just about sufficient 

 to surmise the real nature thereof. It will be noticed by the 

 diagram that the primaries occupy by far the largest area. 

 They consist chiefly of granite, gneiss, quartzites, sandstones, 

 and conglomerates from the Ardrossan to the first medial 

 ridge. This fact partly accounts for the monotony and poverty 

 of the vegetation, especially if it be remembered that the 

 physical properties of the limestones favor a rapid percolation 

 of the rainwater, thus producing a scarcity or rather absence 

 of surface moisture. At Yorke Valley and west of Maitland 

 a more tenacious and retentive clay prevails (probably derived 

 from decaying slates), and consequently vegetation is much 

 more luxuriant. 



A few words on the temperature and other meteorological 

 relations may not be amiss. As to the first, the observations 

 scarcely extend beyond the neighbourhood of Ardrossan, and 

 appears to be similar as at Port Adelaide and the Semaphore. 

 In winter it is mild, frost is scarcely known, and the ther- 

 mometer is seldom less than 55° E. in the daytime. In summer 

 it has been observed as high as 116° in the shade (19/1/80), 

 but the nights are always cool. The annual rainfall is about 

 equal to the average of the province ; rain falls frequently, 

 but generally light, and of short duration. The winds seem 

 more regular than on the main land. During the warmer 

 season the cool south-east is the most prevailing ; it is ever 

 accompanied by dry and fair weather. In winter and early 

 spring the south-west bears sway, generally dry ; it sometimes 

 brings heavy showers, and is always cold and bracing. The 

 north-west winds are not very frequent, even in summer, when 

 they are as bot as elsewhere ; but in their train ever comes a 

 speedy change and often rain ; in fact, they are the true rain 

 winds, as far as steadiness and continuity goes. The rarest 

 winds are those from the east, very cold and cutting, and when 

 accompanied with rain Australians do feel it cold. The changes 

 in the weather, in the whole, appear to occur very regularly 

 in the following sequence : — S.E., cool, fair, dry ; E., cold and 

 dry, sometimes drifting rain ; ]N~.E. and IS"., hot, sultry, dry, 

 curnulus clouds gathering, either followed by steady rain, the 

 wind gradually shifting through "W. to S.AV., with tbe rain 

 breaking up into showers, frequently very heavy ; or the wind 

 suddenly shifting to the S.~W., driving clouds of dust before it, 

 and cooling the air within an hour or less from 116° down to 



