|
Abstract
|
The large area of land derived from basaltic material in the south-western part of Victoria is interesting from several points of view. Part of it produces high-grade wool; in other sections there are extensive dairying settlements; and near the volcanic cones, which are scattered about the district, there are fertilesoils which are largely used for producing crops such as onions and potatoes. Even casual observations show that the number of soil types is quite considerable, although the basalt itself is petrologically uniform over wide areas. A detailed study of a single area in this district has been undertaken in order to obtain useful information concerning a group of soils about which little has as yet been published, and also to explain some of the reasons for the differences between these types. Since this volcanic country includes various kinds of pasture, and numerous attempts at improvement of pastures have
been made with varying success, the relation between soil types and pasture has also been studied.
It was decided to choose for this survey some point that would by typical of the volcanic country, and in which the geology would not be complicated by non-basaltic material. Mr. R. A Ramsay of “Mooleric” and Mr. Urquhart Ramsay of “Turkeith” were kind enough to agree to co-operate in this work. These two stations comprise about 12, 00 acres, and are fairly close to the Prince’s Highway at a point about half way between Winchelsea and Colac. Mount Gellibrand near the centre of this region provided one volcanic cone in the area surveyed.
Surveyed maps of the stations, on a scale of 1 to 6,336 were made available through the courtesy of the owners, and these were used for the first stages of the survey. However, after the main soil types had been recognised, it was clear that it would be very laborious to try to map the area on the ground, owing to the extent to which the various types are interwoven. The Royal Australian air Force were therefore approached, and asked it they could make the area the subject of a photographic survey.
They very courteously agreed to help, and the photographs were taken on 30th September, 1932, when the water from the winter rains was still lying on the least drained swamps, and the spring growth had begun on the drier land. Three photographic mosaics, on a scale of 1 to 6,840 were prepared, and these were used in the field for the next visit. These aerial photographs are invaluable, and, as will be shown in more detail below, it is possible after a few days’ experience to identify each type of soil and map it directly from the photograph. These sketches were then checked by visiting each paddock, and identifying in the field the soils deduced from the photograph; the final map is reproduced in this paper. |
