This Record describes a seismic refraction survey along part of the Forth River near Devonport, Tasmania. The aim of the survey, which was requested by the Hydro-Electric Commission of Tasmania, was to ascertain the depth to the bedrock and the type of bedrock on the site proposed for a dam.

Explanatory notes, Mackunda Sheet, Queensland. (BMR Explan. Notes and map.)

In 1960, the Bureau of Mineral Resources, in association with the Geological Survey of Queensland, commenced a programme of regional mapping in the Bowen Basin, Queensland, to assist in the search for oil. This Record is a progress report on five weeks mapping in the western part of the Mackay 1:250,000 Sheet area (referred to hereafter, as the Mackay West sheet area).

This report covers the work of a combined Bureau of Mineral Resources and Geological Survey of Queensland field party which mapped the southern half of the Bowen 1:250,000 Sheet area during the three months June to September, 1961; This was part of a continuing programme of regional mapping of the Bowen Basin, commenced in 1960. The area mapped includes: the northern end of the Bowen Basin, except for an extension to the north occupied by Lower Bowen Volcanics only; the northern end of the Anakie High; upper Devonian to Carboniferous sediments and volcanics dipping east off the Anakie High; the northern end of the Drummond Basin; the Carboniferous Bulgonunna Volcanics forming the western basement to the Bowen Basin; and the Urannah Complex forming the eastern margin of the Bowen Basin.

The Irrigation and Water Supply Commission of Queensland requested the Bureau to test geophysical methods in the search for underground water in shallow basins, coastal plains, or river flats. Locations south of Bundaberg were selected as test areas. The application of the seismic refraction method and resistivity depth probing showed promising results.

This Record describes a geophysical survey for Underground water in the Cloncurry River valley, at the request of the Queensland Irrigation and Water Supply Commission, on behalf of the Cloncurry Shire Council. Appreciable differences in ground water level in different sections along the valley suggest the presence of rock bars across the valley. In choosing bore sites it is desirable to know the position of these rock bars. Plate 12 shows the location of rock bars that were indicated by ground water level data. Plate 13 shows the position of rock bars that were indicated by geophysical data. Good agreement exists between the two sets of indications. Sites that were based on geophysical data are suggested for water bores.

The Alice Springs Town Basin is a small alluvial basin with a surface of approximately three square miles. It contains a maximum thickness of seventy-five feet of fluviatile sediment, deposited by the Todd and Charles Rivers. The lithology of the sediments is correlated with their postulated environments of deposition. The environments are alluvial fan, main graded channels, levee banks, flood plains, and back swamps. The occurrence of groundwater in the various types of sediments is discussed. Contour maps of the piezometric surface, have been constructed for October 1957 and October 1961. Within this period there has been a fall in the surface of between three and ten feet. The interpretation of the results of aquifer performance tests on bores 28 and 110 gave mutually consistent values for the aquifer constants within the zones of high permeability. The average values are T = 20,000 gallons per day per foot and S = 0.05. The constants computed for the test on bore 59/11 are inconsistent with the assumption of an isotropic, homogeneous aquifer.

A reconnaissance survey of the Brighton Downs 4-mile Sheet area was conducted by geologists R. R. Vine and W. Jauncey of the Bureau of Mineral Resources between June and August, 1961. Cretaceous rocks crop out over nearly the whole of the Brighton Downs Sheet area. Lower Cretaceous marine sediments appear in the north-west and dip gently eastwards below freshwater deposits of Lower to Upper Cretaceous age. In two main areas of Tertiary sedimentation, one in the north and the other in the south-west, sandstone, clay and limestone have been deposited. Lateritisation is widespread over the area.

Lower Cretaceous strata of the Calvert Hills 1:250,000Sheet area were examined during the 1961 field season. Field observations of lithologies and their sequences together with the collection of fossils and their identification provided material for this Record. Fossil content and field observations suggest that Mesozoic sediments on the Calvert Hills 1:250,000 Sheet area were deposited in distinct environments at three different times in the Lower Cretaceous

Lower Cretaceous strata of the Roper River and the Urapunga 1:250,000 Sheets were examined during the 1960 and 1961 field seasons. Field observations on lithology and palaeogeography were summarised in previous Records (Skwarko,1961a,b), and these, together with the identification of the fossils collected and their dating has provided material for this Record. Fossils were collected at only three localities on the Roper River 1:250,000 Sheet area, the greater portion of which is at present covered by the sea, and it has been found convenient to discuss these two sheets under a common title.