ARTESIAN WATER IN N. S. WALES AND QUEENSLAND. 415 
As regards (1) the strata of the Rolling Downs Formation are 
chiefly clayey, as far as proved at present by the artesian bores. 
The basal beds however, are sandy, and even gravelly in places. 
Few data are available for estimating the thickness of these basal 
beds, for the following reason :—as soon as the top of the basal 
beds are struck the artesian or sub-artesian water in them rises in 
the bore to about its maximum height, and the object of the bore 
having been attained, the bore is discontinued and is not carried 
down through the whole thickness of the basal beds to the bed- 
rock. In afew cases however, the water-bearing drifts have been 
penetrated, and their thickness has been proved, as far as the 
author is aware, not to exceed from fifty to one hundred feet. No 
bores to his knowledge have been sunk in the basal-beds of the 
Rolling Downs Formation, where they abut against the Lower 
Mesozoic and Paleozoic Rocks of the Main Dividing Range. The 
approximate thickness therefore of the porous beds along their 
outcrops can at present, until more data are available, be merely 
a matter of inference based on certain broad facts. The Rolling 
Downs Formation is of vast superficial extent and of considerable 
thickness. 
At Malvern Hills 3,926 feet of strata of this age had been 
been proved in an artesian bore up to February 20th, 1894 (as 
the Hydraulic Engineer kindly informed the author while this 
paper was being revised up to date for press), the bore being still 
in progress, and the high temperature of the water at some of 
the bores proves that some portions of the Cretaceous Basin 
must be considerably thicker. For example, at No. 3 Boise, 
Darr River, Queensland, the temperature of the water is 172° 
Fah. If the mean surface temperature at the Darr River be 
70° Fah. there is an increase of 102° Fah. in the temperature 
-of the water flowing from this bore, as compared with the surface 
‘temperature. Ifthe downward rate of increase be 1° Fah. for 
every sixty-three feet in depth, the depth below the surface of the 
locality where the water acquires this high temperature would be 
over 6,400 feet. It is extremely improbable that so vast a forma- 
