An examination of a small area flanking the Molonglo River at Acton was undertaken at the request of the Department of Works and Housing. The construction of the weir across the river within the area examined to raise the water level to 1825' is proposed, and the geological investigation was carried out in connection with this proposed work. Aspects of general geology and engineering geology are discussed. A geological plan and sketch sections are included.

The four field parties and the Airborne Geophysical Section continued operations in the area during the quarter ending 30th September, 1953. This report provides a summary of the geological and geophysical operations carried out during this period, and an overview of the staff and housing situation.

The establishment of seismological and magnetic observatories at Heard Island is described. Brief descriptions and photographs of the huts and instruments are given. Earthquake phases recorded between April 1951 and February 1952 are listed, as are absolute magnetic observations made between July 1951 and January 1952. Although Heard Island has two active volcanic craters, the region is not very active seismically. Only two near earthquakes were recorded, both probably 2°.9 distant along the Kerguelen ridge. The absolute magnetic observations showed that the high rate of secular change in declination and horizontal intensity is continuing.

This report covers the work done by the author who was geophysicist with the Australian National Antarctic Research Expedition at Macquarie Island from April to December, 1953. It is a sequel to Records 1953/30 and 1954/32 and deals with observatory routine and maintenance and other general duties required of the geophysicist. The report contains the results of absolute magnetic observations and initial earthquake phases. Detailed tables of scientific results will be published separately in reports at present in preparation.

The principal alternative sites for an administrative centre which have been considered or suggested are discussed from the points of view with which a geologist and vulcanologist is primarily concerned - namely vulnerability to volcanic action, earthquakes, and tidal waves, foundations, water supply and accessibility of material suitable for road resurfacing, aggregate, etc. The areas considered are Rabaul, Nonga-Tavui, Keravat-Kabaira, Vunakanau-Taliligap, and Koko-Rapopo.

In response to the proposal for a new administrative building to be erected, 1/4 mile east of Parliament House, nine test pits were put down by the Department of the Interior for the purpose of examining the sub-surface conditions. Four of the pits were used for engineering tests of the bearing power of the rock foundations. The geology of the site is discussed in this report.

An examination was made of a proposed dam site at Geehi in April, 1947. The report comprises notes on access, general geology, evidence gathered from aerial photography, and the suitability of the site. Three accompanying plans, and a petrographic report on rocks collected from the vicinity, are appended to this report.

The refraction seismic tests described in this report were made at the request of the Victorian Railways Department. The work was located within the railway reserve between the outskirts of Wodonga township and the River Murray, and consisted of the shooting of five refraction traverses, set out approximately parallel to the railway line and covering in detail a total length of 4,800 feet. The aim of the seismic work was two-fold. Firstly an investigation was required of the subsurface formations in the vicinity of the bridges which carry the railway across several creeks intersecting the Murray flood plain. The subsurface information is required in connection with the design of the foundations of new bridges which will be constructed to replace the existing ones. The second purpose of the work was to test whether the refraction seismic method would be suitable for adoption by the Railways Department engineers as a standard routine method for investigating foundation conditions. To fulfil this purpose ideally, the method would need to be applicable generally to all the foundation problems encountered by the Department and to completely eliminate the necessity for test drilling of sites. The flood plain of the Murray, on which the seismic measurements were made, is composed of Recent alluvium, probably underlain by Tertiary river deposits and is crossed by several creeks and anabranches of the main stream. The outcrops in the vicinity of Wodonga show the bedrock to be granite and metamorphic sediments. The field work was done between February 26th and March 12th, 1953. The field party comprised two geophysicists and three field assistants provided by the Railways Department.

In November, 1945, the Department of Works and Housing requested that a Geological Survey be made of a section of the Upper Cotter Valley in which it is proposed to construct a dam. Four possible dam sites were examined along the Upper Cotter River between Bushrangers and Collins Creeks. This report deals with the geology of the area examined with special reference to possible dam sites. The report is also intended as a basis for future regional work in the area lying west of the Murrumbidgee River where little is known of the geological structure and stratigraphical sequence.

An area of about 300 square miles was geologically surveyed in the Upper Murrumbidgee - Tumut River area. The object of the work was to investigate dam sites and tunnel lines in connection with a Hydro-Electric Scheme by which it is proposed to transfer water from the Murrumbidgee River into the Tumut River. Two proposed dam sites were examined. A detailed account of the topography, general geology, and engineering geology of these sites is given in this report. Accompanying geological plans are included.