The distance from Swan Hill to the sea, following the channel of the Murray River, is about 950 miles.
The fall of the surface to Swan Hill is—from Bung Bong, 2 feet 6 inches; from Charlotte Plains, 2 feet 9 inches; and from Baringhup, 2 feet per mile. But the fall of the surface to the sea, by way of the channel of the River Murray, is only 2.75 inches per mile, and even that is not much, since, at Morgan, 400 miles up from the sea, there is only from 3 to 10 feet above sea-level according to the season.[1]
Thus, if these Deep Leads are imagined as being restored to their former condition of rivers, they could not flow out to sea by way of the River Murray unless the land were raised up, taking the mean of the three examples first given, by about 270 feet above its present height as compared with the sea-level. This height of 270 feet may, moreover, be taken as the minimum elevation required, since it would give no more than the present fall, which is improbable, when the character of the sea bottom in Bass Strait is taken into consideration.
The fall southwards of the country from the Main Dividing Range, near Ballarat, to the sea is, also for a long distance over Newer Volcanic basaltic plains, analogous to those through which the above-mentioned bores have been put down.
Here also the Deep Leads trending southwards have been proved by boring, and analogous results have been obtained. But it must be borne in mind that there is a marked difference in distance to the sea in this direction. From Bung Bong, for instance, to the sea is 1150 miles by the Murray River Valley, while from Mount Mercer, where there is one of the most southern bores, to Bass Strait is only 50 miles. Thus compared with the distance, the fall of the land in the latter case is much steeper.
A bore put down to the west of Mount Mercer proved the Deep Lead gutter at a depth of 113 feet from the surface, and one at Glenfine, near the Woady Yalloak River,
- ↑ Mr. Stewart Murray, Chief Engineer of Water Supply, Victoria, has furnished me with these heights above the sea of the River Murray.
