.4 0.152535

3418.5

•4 0.349273 3097'5

*5 0.155952

3415 5

*5 0.352367 3090.5

'6 0.159366

3412.5

3405.0 .8 0.361604 3067.5 .8
3401.5 ⚫9 0.364668 3060'0 .9
3398 0 11.0 0.367724 3052.0 17.0

2547.5
2537 0
'6 0.355454 3083'0 ⚫6 0.524742 2526'5 '6
3409'0 ⚫7 0.358533 3075.0
0.527263 2515'0 •7
0.529772 2504.0 .8
0.532271 2493.5 ⚫9
0.534759 2482.5 23.0

234567

2590 5 22.0
2580'0
2569.5 •2

0.644076

1874.5

1 0.645944

1861.0

0.647798 1847.5

⚫3 0.346172 8105'0 3 0.517115 2558.5 ⚫3 0.649639 1834.5

•1

0.176383

0.370772 3044.5 1
0.663891 1728-0
0.373813 3037'0 .2 3.539701 2459.5 •2 0.665612 1714.5

2471.0 •1

2380.5 .9 0'677284 1620°C 0.559017 2369 0 24.0 0.678897 1606'0

0° 0' 0 to 24° 5' 41'4...

2391.5

THE PROBLEM OF THE GREAT AUSTRALIAN ARTESIAN BASIN.

By ALEX. L. DU TOIT, D.Sc., F.R.S.S.Afr.

(Communicated by Mr. J. E. CARNE.)

[Read before the Royal Society of N.8. Wales, July 4, 1917.]

I. Introduction.

II. The Physiography of the Basin.

III. The Geology of the Basin.

IV. The Temperature of the Waters :

(1) General.

(2) Secular changes.

V. The Salinity of the Waters.

VI. The Gases in the Waters and their Origin.
VII. The Rising of the Waters under Pressure :—

(1) Gas Pressure.

(2) Rock Pressure.

(3) Temperature Differences.

(4) Hydraulic Pressure.

(5) Sub-surface Springs.

VIII. The Absorption and Transmission of Water:

(1) Absorption.

(2) Transmission.

(3) Interference of Bores.

IX. The Early Tertiary History of the Basin.

X. The Relation between Volcanism and the Artesian Supply. XI. The Closing History of the Basin.

XII. Conclusion.

Table A.-Flows producible in Bores by Gases.

Table B. Friction in Bores according to Depth and Yield.

--

Diagram I. Map of Basin showing Contours of Floor.

Temperature Gradients.
Salinity of Waters.
Isopotentials for 1912.

I. Introduction.

By reason of its colossal size and extraordinarily economic importance, the Great Artesian Basin of Australia eclipses all others, and the interest therein is heightened by the exceptionally fascinating nature of the problems of its structure and mechanism.

For many years the obvious view that the basin owed its immense supply entirely to rainfall absorbed on its eastern and south-eastern margin, remained almost unquestioned, and it was not really until in 1906 Prof. Gregory' showed that many of the facts were irreconcilable with such a simple scheme, and that the meteoric theory was seriously challenged.

He concluded that a certain part at least of the water was of magmatic origin, some was probably water included in the sediments during their deposition, or was a subsequent though ancient accumulation from the atmosphere, and only the remainder was being drawn from the present rainfall, or that of very recent times, while in 1911' he went so far as to deny even the importance of the lastnamed action.

In 1912, Mr. Symmonds, 3adducing many reasons backed up by chemical data and going even further than Gregory, concluded that the bulk of the water was "juvenile” or of plutonic origin.

4

Against such views Mr. Pittman, until lately Government Geologist of N. S. Wales, the most uncompromising protagonist of the meteoric theory, vigorously protested,

1 J. W. Gregory, The Dead Heart of Australia, London, 1906.

2 J. W. Gregory, The Flowing Wells of Central Australia, Journ. Roy. Geogr. Soc., Vol. XXXVIII, 1911.

R. S. Symmonds, Our Artesian Waters, Sydney, 1912.

E. F. Pittman, Geol. Surv. N. S. Wales, especially, Problems of the Artesian Water Supply, etc., 1908; The Great Australian Artesian Basin, 1914; The Composition and Porosity of the Intake Beds, etc., 1915.