Reviews—Stanford’s Geography —Australian Geology. 429 
Australia.” Between the Western Plateau of Australia and the 
East Australian highlands le the great plains of East Central 
Australia, which are for the most part arid, and contain little or 
no surface-water. But deep below the surface there are sands and 
shales saturated with water, which is under such high pressure that, 
when bores are sunk through the clays forming the top of the under- 
ground reservoir, the water rushes up the borehole to the surface and 
discharges as a flowing well; there are also natural outlets for 
this pent-up water. In 1882 Dr. R. L. Jack concluded from the 
geological structure of Queensland that a supply of artesian water 
might occur in the west of that state. A borehole was completed 
in 1888, a water-bearing layer being reached at a depth of 1,645 feet, 
when the water rose to the surface and discharged nearly 300,000 
gallons a day. Since then, alike in New South Wales, in Queensland, 
and in South Australia, numerous ‘artesian’ wells have been sunk, 
the deepest being 5,046 feet; some of this water is warm and much of 
it highly saline. 
The author accepts the term ‘artesian’ in a general sense, and 
observes that the rise of water in these wells has been attributed to 
the hydrostatic pressure of the water occurring in the same layer 
of rock at a higher level in the Queensland hills. It was thought, 
for instance, that the wells were supplied by the percolation of rain- 
and river-water through a porous stratum extending in a continuous 
layer under the clays of the Rolling Downs formation so characteristic 
of the central plains. 
The well-water was thought to be meteoric water which had fallen 
on the eastern hills and was thence flowing westwards, as a sub- 
terranean river, on its way towards the southern sea. It has been 
proved, however, that the porous stratum in question is a limited 
formation quite unable to supply all the wells that have been sunk; 
many of them derive their water from the shales and mudstones of 
the Jurassic beds. In the ‘‘ Dead Heart of Australia” the author 
has pointed out that the simple artesian theory does not explain the 
facts. The chemical characters of the well-waters, the thermal 
phenomena, the irregular distribution of the water pressure, the 
association of the water with various gases, and the tidal rise-and- 
fall of the water in some of the wells present a series of phenomena 
none of which agree with the hydrostatic theory. He expresses 
a belief that the ascent of water in these boreholes is mainly due- 
to the tension of the included gases under the pressure of the 
overlying sheets of rock. Much of the water is an old accumulation, 
some of which may have been derived by percolation from meteoric 
sources; much of it is probably of plutonic origin, having risen through 
deep springs from the underlying rocks, and some of it may be old 
sea-water in the Cretaceous beds. Opinion inclines to the view that 
there is no fear of exhausting the artesian water, but the author 
believes that the existing waste is unfortunate, since the supply may 
not prove inexhaustible. 
Professor Gregory seems to have arrived at this modified ‘artesian’ 
theory slowly and by degrees. Those who have read his interesting 
explanation of the hydrostatic conditions as applied to the hill-country 
