This report provides a summary of volcanic activity in the volcanic centres of New Guinea for the year 1951. Extended descriptions are given of ongoing investigations and the volcanological observations made at Rabaul, Mt. Lamington, and other significant volcanoes.

On May 3rd, and again on June 1st, the author visited the Cotter dam to investigate a reported loss of water from the fault on the northern side of the wall. This report gives an account of these visits, together with the author's observations and conclusions in relation to the reported water loss.

The Nunyerrie Asbestos Deposits are associated with a remnant of metamorphosed ultrabasic rocks in granite country, which is part of a group of Pre-Cambrian rocks of Archaean age. The ultrabasics form an east northeast trending ridge about 1 mile long and 250 feet average width, which rises to a maximum elevation of 300 feet above the general level of the surrounding country. The belt of ultrabasics is highly sheared and jointed and consists chiefly of serpentines, but talcose rocks, chlorite schists, authophyllite rock and what appear to be hydro-biotite schists also occur. The ultrabasics have an intrusive junction with the surrounding granite rocks, and they are intruded by quartz veins and granitic dykes. The deposits were investigated by the author. This report gives an overview of the deposits. Workings, production figures, reserves, grades, and prices are described.

The object of my trip to the United States of America was to discuss problems of micropalaeontology with various authorities in that country, to visit the palaeontological laboratories of the United States Geological Survey and National Museum, State Universities, Museums and laboratories of oil companies and to enquire into the latest techniques used in oil-field laboratories. I was also to attend the joint Annual Convention of the American Association of Petroleum Geologists, Society of Economic Palaeontologists and Mineralogists and Society of Exploratory Geophysicists at St. Louis. This report gives an account of the institutions visited by the author and the principal results of the visit.

An earlier report (Record 1950/041) has described the geophysical survey carried out early in 1950 on the Renison Bell tin field. The present report deals with the work of a second field season which commenced in November 1950 and continued until June 1951. The methods used were again the magnetic and self-potential. The 1950 survey was extended to the south and east by continuing along the Renison Bell Hill base-line a further 1000 feet south and reading stations on both sides of this base-line along traverses extending from the main quartz-porphyry dyke to the headwaters of the Montana Creek. In addition, some of the traverses were extended over the saddle between Dreadnought and Stebbins Hills as far as the Boulder tramway. The report gives an account of the survey work and its results, and provides recommendations for future testing. The geological features of the area covered by the present geophysical survey are briefly described.

At the request of the Government Geologist of Western Australia some gravity observations were made near Bullsbrook, a small township on the Perth-Geraldton road, 27 miles from Perth. It was thought that the gravity observations would help resolve a problem connected with the water supply of the township on which the advice of the Geological Survey of Western Australian had been sought. Because the gravity method had proved successful elsewhere in determining the thickness of sediments overlying dense basement rocks, it was though that some estimate of the thickness of sediments underlying Bullsbrook could be made by using the method. This report gives an account of the operations and their results.

A provisional Isogonic Map of Australia and New Guinea for the epoch 1950.5 has been prepared by revising the observational material used in the Isogonic Map for 1942.5, and including observations made at various parts of Australia since 1942. The extensions of the Isogonic Lines beyond the coast line of Australia depend almost entirely on extrapolation from the earlier work.

Attention has been directed to the cobalt workings at Carcoar as a possible source of radioactive minerals in two ways. During testing of museum specimens for radioactivity, it was found that cobalt ore from Carcoar was strongly radioactive. Also, the occurrence of uranium in the cobalt ores was reported by Mr. McKillop, formerly a land holder in the area, who submitted a copy of a report signed by Professor T.H. Laby, certifying the presence of uranium in samples examined by him, and at a later date, a sample containing an uranium mineral. A brief visit was paid to the area in 1948, and the presence of strong radioactivity on dumps was confirmed. A more extensive survey of the area was, therefore, undertaken by geophysicists during 1949-50 and 1950-51. This report gives an account of the geophysical operations carried out in the vicinity of the Carcoar cobalt workings and describes the results of these investigations.

A reconnaissance geological and radiometric survey of the Mt. Cavenagh area was carried out by B.P. Walpole and J. Sleis of the geological section and J. Daly and D. Dyson of the geophysical section of the Bureau of Mineral Resources. The objects of the survey were to examine reported occurrences of radioactive minerals in this area and to determine whether further prospecting of the area for radioactive orebodies was warranted. The general geology of the area, and the economic geology of the six prospects examined, are described in this report.

The geophysical survey described in this report was undertaken at the request of the Snowy Mountains Authority for the purpose of investigating possible sites for the proposed Spencer's Creek dam. The area surveyed is about two miles above the junction of Spencer's Creek with the Snowy River, about six miles east of the summit of Mt. Kosciuszko, and at an average elevation of about 5,700 feet above sea level. The specific information sought by the survey comprised the following: depth and nature of the bedrock, contours of the bedrock surface, nature of the overburden, and in particular, variations in physical properties occurring either horizontally or vertically. The seismic refraction method was used in the survey. This report gives an account of the geophysical survey and its results.