A micropalaeontological examination was conducted on a sample of diatomite from Redesdale. The results of this examination are described here.

As a result of abnormal rains in 1950, a considerable body of water has been impounded in Lake George, situated in New South Wales, but only 20 miles north of Canberra, Australian Capital Territory. Local reports claim a depth of water of 30 feet in the Lake and these reports have prompted the Advisory Council of the Australian Capital Territory to investigate the possibility of developing the lake as a recreational resort. As a first step in this investigation the Council has asked the Bureau of Mineral Resources, Geology and Geophysics for an opinion as to how long a considerable body of water may be retained in the lake.

A sample of limestone from Bougainville was submitted for micropalaeontological examination. The results of this examination are described here.

The Government of India invited the Australian Government to send a representative to the celebration of the Centenary of the Geological Survey of India during January 1951. The first meeting of the Pan-Indian Ocean Science Congress was scheduled for the first week in January, 1951 so the Bureau of Mineral Resources, Geology and Geophysics selected M.A. Condon to attend the Science Congress and the Centenary Celebrations because his work in the North-West Basin of Western Australia would be of some interest to geologists working around the Indian Ocean. This report comprises a detailed itinerary and geological notes on the areas visited during the course of the visit.

A seismic survey was carried out near Roma during 1949-50, being part of a geophysical programme to search for structures likely to be significant for oil exploration. As preparation and publication of the final report on the survey may take some time it is desired to present briefly the main results in the form of a preliminary report. The first phase of the geophysical survey work at Roma comprised gravity and magnetic surveys, the results of which were presented in Bulletin No. 18. The residual gravity pattern revealed two possible structural high closures. The object of the seismic surveys was to prove or disprove the existence of these structures, and to obtain more detail concerning them if proved.

This report deals with the work done by a field party of the Geophysical Section, Bureau of Resources, on leases in the Astrolabe Mineral Field held by Mandated Alluvials N.L. The work was done in the 1950 field season from March to December and was a continuation of the work done in 1949 and described in the first progress report. The geophysical survey was conducted using the magnetic, self-potential, equipotential-line, potential-drop-ratio, and electromagnetic methods. An overview of the geophysical methods used, their results, and the local geology, is provided for each of the individual areas surveyed in the course of this work.

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.

Three samples of limestone were collected during a geological survey of the Rigo area. One sample is of Upper Cretaceous age and the others of Lower Middle Miocene age. The samples were submitted for micropalaeontological examination. The results of this examination are described here.

This report has been prepared at the request of Engineers of the Department of Works and Housing. The writer spent a day with Mr. Crotty examining the site, and another day alone studying general geological conditions relevant to the proposed scheme. The visit and its findings are outlined 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.