CHARACTERISTICS AND DISTRIBCJTION OF LAKES 563 
What is known as the lake area is a district north of Spencer 
Gulf covered with several expanses of brackish water that contract or 
expand as the season is one of drought or of rain. In seasons of 
drought they are hardly more than swamps or mud-flats, which for a 
time may become grassy plains, or desolate shores encrusted with salt ; 
in the wet season they receive the waters of a vast extent of country, 
including streams from Western Queensland. 
Fig. 67. — Inland drainage areas of Australia. 
I The inland drainage areas are stippled.] 
The rainfall being very irregular, sometimes the rivers rush down 
in flood, carrying torrents of water to the lakes, while at other 
times they are dry for months. Many of the rivers draining inland 
lose themselves in the interior ; they carve out valleys, dissolve lime- 
stone, and spread out their deposits over the plain, when the waters 
become too sluggish to bear the burden further. 
Lake Eyre and Lake Torrens. — North of Spencer Gulf lies Lake 
Torrens, sometimes 100 miles in length, and north of that again 
stretches Lake Eyre, 80 miles long by 40 miles broad, covering 
an area of about 3200 square miles. The two lakes are divided by 
