XXVlll. 
Charles Austin Gardner. 
isolated hills extending from Mount Manypeak through the Barren Ranges 
to the Eyre Range and the Russell Range near Israelite Bay. The Darling 
escarpment averages about 1,000 feet in height, the highest point being Mount 
William (1,689 feet). This escarpment extends from near the south coast 
as far north as the Irwin River, and possesses two subsidiary spurs, one ex- 
tending to the north-west from Gingin, the other, below Bunbury (known 
as the Roe Range) links the main escarpment with the Dunsborough- Augusta 
escarpment between Cape Naturaliste and Cape Leeuwin. 
Most of the drainage is into the sea. While a number of streams are 
short and originate near the margin of the plateau, others, like the Fortescue, 
Ashburton, and Gascoyne, are of considerable length, and originate on the 
plateau. The rivers of Kimberley rise in the Hann plateau ; with the ex- 
ception of the Fitzroy and Lennard rivers, they are perennial, at least in the 
plateau area, and they have, together with their tributary streams, eroded 
narrow valleys or canyons in the soft sandstone. They appear to be yoimg 
rivers, and several of the smaller tributaries have in places tunnelled through 
the soft rocks. Most of them rise in the comparatively high rainfall area 
near Mount Hann. 
South of the Fitzroy River, as far as the Avon, the streams are inter- 
mittent, and flow only in times of heavy rain. They are, in fact, merely 
flood channels which carry water in times of flood. They may remain as 
dry watercourses, containing only a few shallow pools, for several consecutive 
years, or, on the other hand, they may flow twice or more during the same 
year. They traverse low flood plains in their low'er courses, and a character- 
istic of the larger streams is the formation of subsidiary channels of “ billa- 
bongs.” 
The Swan River marks the commencement of those streams which are 
more permanent and have eroded broad valleys. They extend southwards 
to the Denmark and Kalgan rivers. These rivers flow as a rule throughout 
tlie winter months, but in the summer are much reduced, sometimes to chains 
of pools, or in the lower south-west, as for examples the Warren and Frankland 
rivers, they may be permanent. Some of them, such as the Avon, drain 
larger watersheds than appear to be indicated on the map as their defined 
courses, and it is probable that the Avon River once drained a very extensive 
area, since the chain of salt pans and channels which enters the river at Lake 
Mears, can be more or less continuously traced through Lake Brown to Lake 
Ballard. It is only during exceptional seasons that this system flows to the 
sea from above Hine’s Hill, thus accounting for tlie salt-j^an system of the 
upper course. 
Apart from those streams which find an outlet to the sea, there are a 
number of watercourses which very rarely carry rimning water through more 
than a limited portion of their channels, emptying themselves into extensive 
flats or clay-pans. Some of these clay-pans are termed "salt lakes.” \\ith 
the eva]joration of the water in these depressions substances such as salt and 
gypsum are deposited. Many of these so-called ‘'lakes” may be of con- 
siderable extent, such as Lake Moore and Lake Carnegie. They are either 
fpiitc isolated, or they are constellated over the interior in a manner that 
suggests that they once formed old river beds forming part of an ancient river 
system. The largest of these ancient systems is that which extends from 
Lake Nabberu to Goddard’s Creek near Zanthus. Its ancient course once 
entered the sea near Twilight Cove, and it constitutes the largest watershed 
in Western Australia. 
The physical features described are important because of their effect 
ujDon the flora, and upon the climate. The river systems are important be- 
