In connection with the use of airborne equipment for the detection of deposits of radio-active minerals, the Bureau has successfully used a DC.3 aircraft for the rapid coverage of large areas. It has been frequently suggested that a helicopter would have the following advantages over a conventional aircraft: (i) It can fly safely at lower heights and slower speeds than an ordinary aircraft, thus obtaining greater sensitivity from the detecting apparatus; (ii) It can be used effectively and safely in mountainous areas, in which low flying by a conventional aircraft would be impossible; (iii) It would enable the observer to locate exactly and identify from the air any small area on the ground showing radio-activity. In order to assess the performance of helicopters, a programme of test helicopter-mounted equipment over selected areas in New South Wales was carried out during March, 1953. The areas selected were: (i) Carcoar. This is a hilly area, but not timbered; (ii) Wunglebung, near Tenterfield. This is a mountainous, heavily timbered area; (iii) Broken Hill. This is a relatively flat featureless area; (iv) A test run was also made over Plen's deposit at Toongi, near Dubbo, in order to obtain and check on the sensitivity of the detecting instrument. The survey techniques used and the results obtained in the several areas are discussed in detail below.

The 1953 field reports refer to several rock units of the Cambrian sequences of the Undilla Basin without defining the units. These units were established in previous years, but all the records and prepared reports were destroyed in the autumn of 1953. The author used this nomenclature in his field reports on the assumption that it would be known to prospective readers. In the present report the definitions are given in a brief and preliminary form. The field maps show the distribution of the rock units, but, as the field reports contain no explanatory sections, these are presented here. The study of the collections included the examination of the lithology and definition and determination of the vertical distribution of fossils. The results of the lithological examination will be given later. The vertical distribution of genera and species of fossils, however, shows the existence of a sequence of biozones (species-zones); it indicates the presence of four fossil stages in the Middle Cambrian sequence and is presented in Chart 2. The fossil list is incomplete, and the nomenclature applied is not final.

1952-3 was the third successive year of geophysical work at Macquarie Island. During the previous year Mr. W.H. Oldham was mainly concerned with the preparation of the establishment for future operation as an observatory. This record outlines how, as a consequence, 1952-53 was devoted to full-time technical proceedings in both geomagnetism and seismology. It does not present the results of the scientific observations in full. These will be presented in a further report, but it does give in tabulated form absolute magnetic values observed and seismic phases recorded.

During the Mullins Harbour - Wedau Reconnaissance (South Eastern Papua) carried [out] in 1953 by Mr. J.E. Thompson, Senior Geologist of the Bureau of Mineral Resources, a section was sampled along the Middle Nigo-Nigo River. Of a number of samples sent to Canberra for petrological and palaeontological examination only eight proved fossiliferous. The following is a list of samples examined listing lithology and microfauna determined by the author and the age assigned to each.

Mr. H. B. Owen forwarded specimens collected by Dr. G. Sleis from "somewhere near the base of the Buldiva Group about 50 or 60 miles north-east from Katherine", Northern Territory for palaeontological examination.

The earliest recorded geological work on the area covered by the Minilya four-mile sheet was that of Woodward (1907) who examined the country north of the Minilya River and noted the limestone on the west flank of the Giralia anticline. In 1909 A. Gibb Maitland described the Carboniferous and Permian succession in the area drained by the Gascoyne, Lyons, Minilya and Lyndon Rivers, but referred the whole sequence to the Carboniferous. Geologists of Oil Search Ltd., under D. Dale Condit, examined the Carnarvon Basin in 1932, 1934 and 1935. Raggatt (1936) described the stratigraphy of the Permian in some detail and subdivided the Cretaceous sequence. Raggatt and Fletcher (1937) examined the fauna of the Permian of the Carnarvon Basin. Teichert did detailed stratigraphic work in the Wandagee area from 1938 to 1940. Geologists of the Bureau of Mineral Resources mapped the Minilya Sheet from 1948 to 1951, using R.A.A.F. aerial photographs. The present sheet is entirely the result of the mapping of the Bureau geologists although much of the stratigraphic nomenclature is adapted from Raggatt's and Teichert's work.

The Radioactive Section of the Bureau of Mineral Resources expanded its operations in the Katherine-Darwin Area during this quarter. The staff working in the area has been considerably increased, but more geophysicists are required. Regional geological mapping has commenced for the season and has disclosed one prospect showing radioactivity in the Burrundie district. Detailed geological mapping and radiometric gridding is being done at Burrundie, Brock's Creek, A.B.C. and Adelaide River Prospects.

A seismic reflection survey was carried out in the Parish of Darriman, Victoria. The survey was planned to investigate a gravity anomaly, which may be an indication of a structure within the sedimentary section favourable to the accumulation of oil or natural gas. For the most part reflections were exceptionally good, and it was possible to trace one reflecting layer over most of the area. Contouring showed the presence of an anticlinal structure, plunging to the east, but rising and broadening to the west. On the flat crest of the structure, there is probable closure in two places. The thickness of the Tertiary sediments may be a maximum of 6,000 feet, but may be only 3,000 feet on the crest of the structure and 4,000 feet on the flanks.

Report on the activities of the administrative and technical sections in the Katherine-Darwin area, to July, 1954. A brief account is given of geological and geophysical operations. The results of prospecting and development work are summarised.

The following report concerns the geology and mineralization of two uranium prospects in the Gimbat - Snake Creek Area of the Northern Territory. One of these prospects, referred to as Sleisbeck, can be recognised as one of the most favourable yet discovered in the Northern Territory. The radioactivity occurs in a quartzite breccia outcropping over a length of 1.5 miles and with a width of as much as several hundred feet. Geiger counter readings of 2 - 100 times background, occur frequently along the entire length of the outcrop, visible mineralization being present at three separate localities. The state of this mineralization, its associations and the geological settings are favourable to the possible occurrence of uranium mineralization at depth. Recommendations are made for further work, and problems in regional geology are discussed. The writer considers the sections of this report designated "Mineralization" and "Conclusions" to be the most important for a knowledge of the actual uranium occurrences. The remaining information is mainly geological, and, while highly pertinent, may not be of urgent interest to readers with a limited amount of time.