TRANSACTIONS OF SECTION C. 367 
determine if there be a distinct difference such as Goyder demonstrated in so 
masterly a manner as a safe wheat line (near 13 inches) in South Australia. Only 
by such necessary research can we really gain adequate knowledge of the 
potentialities of Australia, 
Mr. E. J. Anprews : The observations of the writer in lands of sub-arid, or 
arid, character have been made only in Eastern Australia and in Arizona, 
Nevada, and California in the United States. In these regions the surface 
forms testify to the dominating influence of stream action and to the utterly 
subordinate action of the wind in sculpturing the lands. To appreciate the 
part taken in the actual sculpture of desert lands by wind action alone, it is 
necessary to recognise the fact that ordinary water streams produce peculiar 
forms, and that these forms are not the result of the stream activity during 
normal periods, but only during periods of great floods acting perhaps once in 
a decade. Such forms, however, are continuously mistaken for those due to 
wind action, by various observers, and from interpretations such as these the 
action of the wind as an eroding agent is magnified unduly. 
The thalwegs of the Australian and American valleys commence in well- 
marked divides, and their slopes thence decrease continuously towards base- 
level. Tributary thalwegs also enter the main valleys at accordant slopes. 
The bases of these valleys are occupied by pebbles and boulders, while these 
again are covered with deposits of clay and sand. Moreover, certain plants 
characteristic of fairly humid conditions elsewhere occur sporadically in oases 
in Kastern Australia within sub-arid regions, and this evidence taken as a 
whole indicates a very recent decrease in the amount of precipitation in drier 
Kastern Australia. Such action has only slightiy modified the general appear- 
ance of the land forms developed in a previous cycle, save for killing off much of 
the vegetation of that previous cycle. 
Mr. A. L. Du Torr referred to the dry region of German South-West Africa 
and the Kalahari. In the coastal sandy wastes, though wind etching is conspicu- 
ous, no hollows due to the action of the wind are to be found. Inland, hollows 
called * pans,’ often saline and usually periodically filled, occur sunk below the 
general surface, and must have been produced by wind erosion. All kinds of 
pans, from ‘living’ to ‘fossil,’ can be found, just as in the case of the sand 
dunes. 
Mr. A, 'l. Kenyon: The general trend of the speakers’ remarks showed that 
desert or rather arid occurrences were distinctly local, and no generalisation 
could now be made. The area in Victoria which might be called arid was only 
so on account of its rainfall, which averaged about 14 inches. Its vege- 
tation was abundant. No definition of desert had yet been made which was 
really applicable to it. 
The reference to Goyder’s rainfall line, which was undoubtedly fixed by the 
occurrences of salsolaceous vegetation, needed some comment. Salt bushes grow 
on soils suitable to their demands, and rainfall was only a small factor. The 
southern limits of Heterodendron olwifolium, which agreed with the line of 
distinct change from the Buloke or hybrid type of Belar to its typical form, 
me amore reliable guide; but profitable agriculture had long passed even that 
imit. 
In regard to Victorian Mallee saline occurrences, these undoubtedly were 
confined to the lowest trough of a synclinorium, and were the exposed surfaces 
of underground sheets of salt water. This has been proved by a number of 
bores. They were also accompanied by beds or mounds of gypsum or cop as 
locally named, and lime carbonate. The artesian waters of the underlying 
marine beds held the same salts in similar proportions. 
In general, lakes or swamps, the terminals of water-courses, were fresh, 
as were also the swamps or lakes corresponding with Dr. Du Toit’s pans, and 
dependent upon local catchment only for their water supply. 
In regard to sand ridges these ceolian drifts occur all over Victoria in the 
western and north-eastern portions, which are the most fertile parts of the 
State. In the Mallee the size and arrangement of the ridges seem to be 
