The report dated 5th October, 1895, recurs to the Hydraulic Engineer's previous estimate that the outcrops of the water-bearing beds of the country covered an area of about 200 square miles. He is glad to learn that Mr. R. L. Jack, Government Geologist, had since worked the matter out, and, while approving of Mr. Henderson's suggestion as to the source of artesian supplies in Queensland, estimated the area as 5,000 square miles, or twenty-five times the Engineer's estimate. This information seems to have allayed Mr. Henderson's dread of the exhaustion of the supply, for he says that the Geologist's figures indicate that "the gathering-ground is larger than can possibly be required for years to come if there is no extensive leakage, of which as yet there is no evidence that I am aware of." He next writes strongly in favour of a comprehensive search for artesian water by the Government, and of Government aid being offered by loan to persons willing to sink bores on Crown lands or even on private property. Such assistance would encourage settlement by leaving the settler in possession for other purposes of money which would otherwise be spent on water provision on his holding, and prove an incalculable benefit to the State by mitigating periodical droughts.
PROGRESS TO 1895.
The report then gives statistics relative to artesian bores as follows:—Number of bores, 397; average depth, 1,195 ft. Of these 286 overflow with a total output of 213½ million gallons per diem. Total cost of boring and casing, £860,321, as nearly as could be estimated, "remarkable results for eight years' work, as in 1887 boring in Queensland was in its infancy." With a view to greater accuracy provision for the salaries of two inspectors had been made on the Estimates for the year, in order that uniform records might be secured as to the strata pierced, the flow, the pressure and temperature of the water, amount of rainfall at the outcrop of water-bearing beds, and the alleged diminution of artesian streams. The suggestion is then made that land, the leases carrying water rights, might be made available for settlement in small areas around tanks and bores.
THE WINTON BORE.
In this report the Hydraulic Engineer is able to announce the success of the Winton bore. At about 3,555 ft. a daily supply of 720,000 gallons of excellent artesian water was struck, and boring being continued to 4,010 ft. without increasing the supply work ceased, the total cost of the bore having been about £7,000. An article on irrigation shows a total irrigated area of 7,641 acres, an increase for the year of 2,240 acres. Included in the area are 2,000 acres of natural grass land and 2,000 acres sown with artificial grasses; also 11½ acres irrigated from artesian wells in the Warrego district. Flood mitigation is also dealt with at length, and a system of flood warnings on the various streams recommended.
Dr. R. L. JACK'S OPINION.
The report for 2nd October, 1896, brings records up to date. By map it is shown that not only does the water-bearing country extend over 56 per cent. of the area of Queensland, but also continues into New South Wales and South Australia, and enters Western Australia. It "marks the position of the ancient Cretaceous sea which connected the Gulf of Carpentaria with the Great Australian Bight," and "divided the continent into two islands." "They were," wrote Dr. R. L. Jack, "laid down by this sea; their present position is due to subsequent general upheaval, and they lie directly and unconformably on schists and slates of undetermined age, or on granite or gneiss. Except in Queensland, where they are overlaid here and there by the remains of the Upper Cretaceous or Desert Sandstone formations which have not been removed by denudation, they seem to be covered to a considerable extent by Tertiary rocks. The Desert Sandstone beds lie horizontally but unconformably on those of the Rolling Downs, which dip to the south." [a]
[Footnote a:] See "Geology and Palaeontology of Queensland and New Guinea," by R. L. Jack, F.G.S., Government Geologist, and R. Etheridge, jun,. Government Palaeontologist, New South Wales, page 390.