BY JOHN FALCONER, C.E. 



29 



thereby supplying the Oape farmers with splendid springs, 

 about twenty miles apart. The early Dutch settlers " Treyked " 

 northward from spring to spring, as a Dutchman never thought of 

 settling down where he could not get flowing water at some point 

 above his homestead. Some of these springs are sufficient to 

 drive two or three water mills, and they run through every 

 street in their Townships. 



This water has been tapped by boring in the interior over 

 what is known as the " Great Karoo," and the water generally 

 rises to the surface and sometimes overflows. 



In some of these wells the material gone through consists 

 of deposits similar to those found in the Western Downs of this 

 Colony, near Roma. The depth of the Alluvial deposit over- 

 lying the Lacustrine shales, varies, but in every instance once 

 through that into the cretaceous sandstones and coal measures 

 water is a certainty. (PI. vi., fig. i.) 



On the Western Plains of Queensland the rocks nearly all 

 dip from the Main Range to the South-west, over which the 

 water coming down the creeks travels at nearly right-angles 

 to the outcrops and dip. 



On a line drawn parallel to the top of the Main Range, and 

 spurs, and about thirty miles distant from it, water may be struck 

 at a depth of about two-hundred feet, measuring from the bottom 

 of the alluvial deposit, due to erosion, which, in sinking wells, 

 has been seldom taken into consideration. 



Class II. — Springs of Volcanic Origin. 



This description of spring, existing in Queensland, is due to 

 the overflowing of liquid lava or basalt into the old water system 

 of the Colony, the water now getting in round the lip or edge of 

 the basin filled up, flows underneath in the old river beds between 

 the lava and the original surface. 



These springs exist all over Queensland, and their presence 

 may be indicated by patches of red soil, or decomposed basalt. 

 The "Hummocks" are opposed to the hollows or valleys in the 

 bed rock and indicate nearly the original height of the lava plain, 

 and they remain in consequence of having been more consolidated 

 (and so less liable to subaerial denundation) by the extra weight 

 due to the depth of the valley filled up ; whilst the less con- 

 solidated deposited over the original ridges has disappeared by 

 erosion. Thus it happens that in boring through the basalt in 

 almost every case water has been found lying in the old river 

 hollows. (PI. vi., fig. 2.) 



