Dec 



19 



^^'l Sutton, A Sketch of the Keilor Plains Flora 115. 



rainfall rises from 23.11 inches at Sun bury in 20 years, 24.97 

 inches at Yan Yean in 52 years, 26.70 inches at Mickleham in 

 5 years, 24.58 inches at Wallan in 16 years, to 29.25 inches at 

 .Beveridge in 5 years and 30.67 inches at Gisborne in 10 years. 

 On the " sands " the average is about 29 inches, and on the 

 Silurian about an inch more. 



Although more rain falls in the spring and autumn, pre- 

 cipitations are pretty evenly distributed throughout the year. 

 The bulk of the area, as well as the country about Geelong and 

 the Bellarine Peninsula, is termed by meteorologists a " locally 

 dry" or "shadow" area, and the comparative lowness of the 

 rainfall is apparently due, apart from the low elevation, to the 

 interception of the moisture in the south-westerly winds by 

 the high ground of the Otway, and perhaps to a lesser degree 

 the Divide has the same influence on those from the north. 

 In spring and summer southerly winds prevail ; in autumn and 

 winter those from the north are most common and strongest. 

 East winds are by far the lightest and least prevalent. 



As regards air temperatures, records are available only for 

 Laverton and Bacchus Marsh, and do not differ materially 

 from those taken at Melbourne, Brighton, and Camberwell. 



With the surface so sparsely covered and the so frequent 

 occurrence of projecting boulders, the soil temperature must 

 surely be higher than in the other areas. For the same reasons 

 it is pretty safe to conclude that evaporation is greater. 

 Radiation must be relatively high, and frosts are probably 

 more frequent. Sunlight, too, has full play in producing the 

 greatest effects. 



Soil Conditions. 

 The soil is black or reddish, and formed in sittt from the 

 generally closely underlying rock. It is stiff and tenacious, 

 with httle humus, appears to have considerable water-holding 

 capacity, and the proportion " available " for support of plant 

 life is less than that in the " sands," at least. Though the 

 slope is so gradual, water does not anywhere lie long into the 

 summer, no doubt quickly percolating through the vertically 

 Assuring rock beneath ; and in midsummer, under the un- 

 mitigated influences of sun and wind, the surface cakes to an 

 extreme degree and cracks freely. 



The influence of animal life has probably always been present, 

 and it may be safely assumed that these plains have in the past 

 been the favourite grazing grounds of such indigenous game 

 as kangaroo, wallaby, and emu. 



The configuration of the surface and the absence of cover 

 exposing it to the influence of wind and the sun's light and 

 heat in the fullest degree, the comparatively scanty rainfall, 

 the shallow, dark, boulder-containing, heat-absorbing soil, and 



