564 THE FRESH-WATER LOCHS OF SCOTLAND 
a ridge of liills to the north of Lake Torrens, with only one low gap 
in the divide, at a height of 175 feet above sea-level. Lake Eyre 
receives the water drained from 500,000 square miles of country, and 
it absorbs it all, for the lake has no outlet. The region has a soil of 
exceptional richness, an invigorating climate free from malaria and 
other diseases incidental to most subtropical lands, and given water 
the country would be fertile as a garden. To effect this it was pro- 
posed to cut a canal from the sea at Port Augusta to Lake Eyre, and 
so flood its vast basin with sea-water, thereby lowering the tempera- 
ture and increasing the rainfall and the dew. Gregory ^ says this is 
possible, but the length of the canal would be 260 miles, and as the lake- 
surface is 39 feet below sea-level, the fall would be little more than 
an inch to the mile. The channel would have to be cut to a depth 
of 100 feet for 200 miles, and in one place to 200 feet, and it would 
have to be large enough to keep pace with the loss of water from 
evaporation. That this loss would be heavy is evident from the 
fate of the floods that are carried into Lake Eyre by the Diamantina 
and the Cooper or Barcoo Rivers. The quantity of water these rivers 
discharge is enormous, and yet no man has ever seen the lake full or 
nearly full, so that a sluggish 50-feet canal would not be very successful, 
and would probably lead to the choking up of the whole lake-bed 
within thirty years with salt, like a salt-pan, through evaporation, 
which in the Lake Eyre country is, according to Sir Charles Tod,^ 
100 inches a year, and even sometimes as much as 1 inch per day. 
The wind which sweeps across the central plains of Australia has 
dropped its moisture as rain on the highlands near the coast, and is 
therefore dry, and capable of absorbing an unusually large amount of 
moisture. The evaporation from the water-surface of Lake Eyre is 
said to be equal to from fifteen to twenty times the rainfall.^ 
The evidence is very conclusive that the Lake Eyre region was 
formerly one of great fertility. At one time it was evidently a vast 
inland sea. Round such a sheet of water there must have been a 
heavy dew, and probably the rainfall was also considerable, for the 
adjacent steppes were well grassed and fertile, and large trees, now 
represented by their petrified trunks, grew on the plains. The 
waters of this lake were fresh, and it was about three times the size 
of the present one. The rainfall dwindled, the water-level sank, and 
the lake decreased in size. The discharge from the lake was no 
longer sufficient to keep open its channel, which the warping of the 
surface and the accumulation of debris continually tended to close. 
There is no outlet from the deep central basin of the Lake Eyre 
1 See The Dead Heart of Australia, pp. 345 et seq., London, 1906. 
2 Cited by Gregory, o^;. cit., p. 347. 
^ Gregory, ojj. cit., p. 325. 
