WATER CONSERVATION, IRRIGATION AND DRAINAGE IN N.S.W. 227 



of the soil and the excellence of the natural underground drainage. 

 Owing to the comparatively favourable conditions as to rainfall 

 and to the sparseness of settlement, it is not surprising that little 

 has yet been done in regard to irrigation between the summit of 

 the Dividing Range and the margin of the great plains of the 

 Central Division. It may be mentioned, however, that there are 

 cases in which it has been practised in this locality with satisfactory 

 results. In the belt of country referred to, the best instance of 

 the use of water on the land by gravitation which came under the 

 notice of the writer was at Tumut, and the best instance of 

 irrigation by pumping was on the river Namoi above Gunnedah. 

 Along the courses of nearly all the rivers which flow westward 

 there are limited areas of valleys and flats which are eminently 

 suited for irrigation. This remark has special application to the 

 Lachlan, the Namoi, and the Gwydir. 



The great plains of the Central and Western Divisions. — The 

 great field for irrigation is on that immense area of alluvial deposits 

 which cover the greater part of the centre of the State. Any one 

 whe studies the question of the practicability of conducting the 

 waters of our western rivers through these plains cannot fail to 

 notice at the outset the contrast between the great area and depth 

 of the alluvium on the one hand, and on the other the fourth rate 

 magnitude of the mountains from which it came. It would be an 

 interesting exercise for a student of geology to work out theories 

 regarding the height which the mountains reached before the 

 formation of the plains began. Whatever the conclusion arrived 

 at might be, one thing is certain in connection with it, and that 

 is that there is abundance of alluvium to account for the former 

 existence of mountains of great magnitude. In short, the physical 

 features of the country are marred by old age and decrepitude ; 

 but the polished grooves on the granite of Mount Kosciusko show 

 that there was a time of perpetual snows and glaciers, while 

 according to some authorities, the remains of the Diprotodon 

 discovered in places where such animals could not now exist, 

 indicate a period of abundant rainfall such as might be expected 

 in a country rich in mountains. 



