the world, the search for new mineral deposits has been greatly
intensified in recent years and new techniques are being employed.
Our own company in conjunction with other mining companies is
actively engaged in such work in various parts of Tasmania.
This article describes the activities of Lyell- E.Z.-Explorations,
the organisation formed by the Mt. Lyell Mining and Railway Company
Ltd., and the E.Z. Company to explore for mineral deposits within
an area of several thousand square miles in South Western Tasmania.
The exploration resources of both companies have been pooled in
order to provide the technical staff and equipment necessary for
this major project. Work is being directed by a Committee consisting
of officials from both companies. For reasons of proximity, Queenstown
is the base for most operations.
The area is one of the most inaccessible in Australia and apart
from a few families and an occasional survey party, the area is
uninhabited. There are no roads and few foot tracks. A series
of high rugged mountains protect the eastern side and the dense
rain forests of the Gordon River effectively block access from
the north. On the south west side the precipitous shores and occasional
beaches are pounded by the rough seas of the Southern Ocean. The
records of early exploration tell of slow progress and of difficulties
For these reasons the existing maps based on scanty and incomplete
data are not wholly reliable. The main problems to be overcome
were therefore those of speedy access and suitable maps.
The problem of access was solved by contracting for the use of
the A.N.A. Bristol Sycamore Helicopter "Yarrana" (VH-INO Ed) and
the problem of maps by contracting for Adastra Hunting Geophysics
Pty. Ltd., to make a series of aerial photographs of the whole
area from an elevation of 18,500 ft.
During the last summer season, the helicopter was used to fly
three man field parties and their equipment to more than thirty
places up to 80 miles from Queenstown for geological reconnaissance.
Field parties usually reached their destination in 30 to 40 minutes
and were fully effective on arrival. The corresponding journey
on foot with limited equipment would have taken at least as many
hours. The field parties usually remained in the field for two
weeks and each party was in radio contact with Queenstown. The
use of bushmen with local knowledge has assisted the work. All
parties were kept supplied with stores and other needs and a total
of 500 passenger flights was made and 80 tons of material were
The aerial photographs each 9" x 9" square depicting 11 square
miles of country proved to be ideal for recording of observations
and for locating places of interest. They faithfully portrayed
details of all ground features and enabled an experienced geologist
with the use of a stereoscope to interpret the geology of the
rock formations in the country surrounding the area which he had
visited, and thus build up a geological map of the whole region.
This information is being depicted on a large base map, made by
joining up a series of aerial photographs to make what is called
By these means, data were obtained in a few months which by any
other method would have taken several years. At the present time
it is still being assembled.
The interpretation of the information obtained will be assisted
by geophysical surveys. Aircraft of the Adastra Company carrying
sensitive recording instruments are being flown over the area
(covering several hundred square miles per day when weather permits)
at a height of 500 feet above the surface and at a fixed spacing
to measure the magnetic, radioactive, and electrically conductive
properties of the rocks below the aircraft. Ore bearing formations
often exhibit a higher degree of conductivity or of magnetism
than unmineralised formations, and these places may show up on
the graphs produced by the instruments as peaks or "anomalies"
on an otherwise straight line.
The aircraft takes a continuous series of 35 mm. vertical photographs
which allow its course to be plotted upon the mosaic. The camera
is synchronised with the other instruments and this enables the
position of the anomaly to be identified. From the responses so
obtained, in conjunction with geological data it will be possible
to select a number of areas for more extensive investigation on
the ground by geological, geophysical and geochemical methods.
The technique of geochemistry is being used to test soil samples
and stream waters for minute traces of metals to determine possible
areas of concentration which could indicate the presence of an
Thus by a process of elimination the most likely ore bearing areas
are selected and the amount of rough country in which survey and
access lines have to be cut, is reduced to a minimum.
It is hoped that by thus directing the modern prospector to the
most likely areas, the work will ultimately lead to the discovery
of worthwhile mineral deposits.
This more intensive work will be accelerated during this Summer
using A.N.A.'s Djinn helicopter (VH-INP Ed).
Review December 1957, Volume 1 No. 9
Published by Electrolytic Zinc Company of Australasia Ltd.
have been omitted.)
to Doug Morrison for sourcing this article.