E. F. PITTMAN AND T. W.:E. DAVID. E CIIl, 
IRRIGATION GHKOLOGICALLY CONSIDERED wiItH . 
SPECIAL REFERENCE To THE ARTESIAN 
AREA oF NEW SOUTH WALHS. 
By EDWARD F. PITTMAN, Assoc.8.S.M., and T. W. EDGEWORTH 
DAVID, B.A., F.R.S. 
[With Plates XXIII. - XXIV.] 
[Read before the Engineering Section of the Royal Society of N. S. Wales, 
July 20, 1903. ] 
I. PHysIoGRAPHY.—For the purposes of this paper New 
South Wales may be divided into three portions :—(1) The 
coastal plains and eastern foothills of the Main Dividing 
Range; (2) The Main Dividing Range; (3) The Western 
foothills of the Dividing Range and the Western Plains. 
With regard to (1) the rainfall over this area ranges from 
243 inches near Scone to 81 inches at Byron Bay per annum, 
the average of the whole area being about 43 inches per 
annum. This, in ordinary seasons, is ample for the require- 
ments of pastoral, agricultural and fruit-growing industries. 
The question therefore of irrigation in this division is not 
of paramount importance except in isolated areas, where 
river water might be utilised for the purpose, as has been 
~ done at Mulgoa near Penrith. With reference to the 
possibility of the occurrence of artesian water in this divis- 
ion its geological structure may be summarised as follows:— 
From the Macpherson Range on the border of Queensland 
down to about 30 miles south of Grafton there is a basin- 
shaped extension of the Ipswich coal measures of Queens- 
land, known as the Clarence Basin. It consists of sand- 
stones, shales and interbeded coal seams of Triassic Age, 
as is proved by the occurrence in them of the fossil Tceni- 
opteris Daintreei.’ As these beds are the equivalents of 
? Aun. Rep. Mines Dep. 1880, p. 244. 
