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  • Rurnbalara railway siding is 831 miles by rail north of Adelaide, South Australia, and 120 miles by rail south of Alice Springs, Northern Territory. The ochre deposits (Plate 1) are situated in desert country, 15-20 miles northeast of the siding. No permanent water supply has been developed in the vicinity of the mines. Numerous mesas in the district are capped by siliceous laterite (grey billy), and are composed of approximately 150 feet of horizontally-bedded, leached shales and sandstone containing numerous fossils of Lower Cretaceous age. These beds, for which the name Rumbalara Shale is proposed, rest unconformably on the eroded surface of flat-lying, current-bedded sandstones of which the age has not been determined; it is proposed that the sandstone beds be called the De Souza Sandstone. .The ochre occurs in beds 1 to 4 feet thick; the best grade consists of soft, friable, golden-yellow material, free from grit and with good paint-making properties. Throughout the deposits the ochre occurs at the same stratigraphic horizon- at the base of the Lower Cretaceous-and appears to be of sedimentary origin. Excluding 1943 and 1944, annual production during 1940-1948 averaged 500 tons; in 1943 and 1944 production was 1,345 and 1,439 tons respectively. The deposits are very extensive, but prospecting carried out to date indicates that only some of them contain ochre equal in grade to that being mined. However, although there are virtually no proved reserves, the field is probably capable of supplying Australia's requirements of yellow ochre for many years.

  • The Desert Basin covers an area of approximately 140,000 square miles in the Kimberley and Eastern Divisions of Western Australia. Geological investigations have been almost entirely confined to the northern part of the area; the southern part is covered by parallel sand-dunes with a few scattered outcrops and is relatively unexplored. A programme of geological mapping was initiated in the area by the Commonwealth Government in 1948. The entire area is being mapped, using aerial photographs, stratigraphic studies are made and fossils are collected for correlation purposes. The aim of the investigation is the evaluation of the petroleum prospects of the area. During the period 1948 to 1950, mapping has been carried out in Dampier Land and the area north of the Mt. Fenton Fault. The information in this paper will refer mainly to the area already mapped with brief reference to the unexplored area to the south.

  • This report covers the results of a seismic reflection traverse on a portion of the Giralia anticline which has been mapped in Mesozoic and Tertiary rocks in the North-West basin. The work constitutes a part of a general programme of investigation which the Bureau of Mineral Resources, Geology and Geophysics, has been carrying out on Permit areas held by Ampol Petroleum Ltd. in this area. The seismic traverse described herein lies along the main road joining Giralia and Bullara homesteads and crosses the northern end of the Giralia structure. Tests were made with shooting in shot holes and also by air shooting. In addition, a refraction spread was shot along the axis of the anticline. This report gives an account of this investigation. Technical matters, such as interpretation technique and the symbols used in plotting results, are briefly noted. The results of the study and subsequent conclusions are discussed.

  • The samples from Margaret Bay were collected by H.B. Owen during a recent visit to the northern coast of Australia. The collection was made with the hope that microfossils may be found in the rocks which were collected from a twenty foot section exposed at Margaret Bay. The results of the micropalaeontological examination are discussed herein.

  • Ore reserves in the Geiger-Main and Whip Lodes at Radium Hill have been calculated from up-to-date plans and assay data provided by the South Australian Mines Department and results obtained agree closely with estimates made by the Mines Department. Tonnage of ore (not including dilution) to 600 feet depth on Geiger-Main and Whip Lodes and to 400 feet in Main Lode South block is estimated at 337,500 tons containing 938 tons U3O8, corresponding to an approximate average of 160 tons U3O8 per 100 feet of vertical depth. The data used, method of calculation, and results, are discussed at length in this report.

  • The presence of bauxite on one of the Wessel Islands was established in 1949 when specimens of laterite collected from various parts of the Arnhem Land coast were analysed. In October, 1951, the writer spent two days on Marchinbar Island and examined several small laterite residuals and part of one large deposit. The characteristics and distribution of the laterite are discussed in this report.

  • This report presents the results of a gravity reconnaissance survey which was carried out under the writer's supervision during the last quarter of 1950. The report describes in some detail the methods adopted in carrying out the field work and the errors to which the results are subject. The results are discussed only briefly and the interpretation given must be regarded as a preliminary one subject to modification as further data are accumulated in extending or otherwise adding to the reconnaissance.