73 
elusion has always seemed to the writer quite unavoidable that 
these scarps have been formed ])y the Ijreachinj? action of a cou 
siderable body of water occupying the area now rci)resented l)y the 
])lains. (Juitc similar “Breakaways” are seen in parts of the shores 
of Lake Lefroy and Lake Cowan at the i)resent time, and the 
scenerv along almost any of these "breakaways' continually recalls 
that seen along any sea or lake sh{)re which is fringed with water- 
worn cliffs. When we sec the features characteristic of cliffs caus- 
ed by sea or lake erosion, reproduced along the shores of salt lakes 
like Lakes Cowan and Lefroy. which are almost certainly raised up 
l)ortions of an ol<l sea inlet, extending deep inland from the south 
coast, and lind them again further north round the plains of which 
other salt lakes and salt i)ans are the lowest depressions, the con- 
clusion seems irresistible that the mulga-clad i)!ain of the north is 
merely a somewhat later stage of the salt lake basin fur- 
ther south, and that the surrounding ‘’breakaways” ret)resent the 
cliffs formed when these ])lains were occu])ied by large bodies of 
water. 
When speaking of the "breakaways” of the Murchison, Last 
Murchison, and Mt. Margaret goldfields, wdiich are the part of the 
country in which the finest examples of this feature are to be 
found, it is necessary to notice one very striking characteristic of 
many of them, which recpiires to be ex})lained by any jjhysiographi- 
cal theory which attempts to account for the present relief of the 
country. Most of the best marked "breakaways” are flat-topped, 
and a little examination shows that the llat-toi)S arc remains of an 
old plateau which has i)een very extensive. 1 he Mat-topped Hill 
at Cue for example wdtich is now an isolated "stack' or "butte 
has evidently been part of the adjacent flat-topped hills nearer the 
towm, which like it. are capped with a lateritic covering derived 
from the kaolinised granite forming their lower portions. At in- 
tervals all round the Cue plain this plateau is seen, especially a' 
few miles to the east of Gabanintha on the road to Wiluna. and on 
the south side of the plain, where the cliffs are so prominent as to 
have found special mention on the maps. Other good examples 
are seen on the road from Cue to "The Pinnacles.” The present 
])lain a])pears to have been excavated to a de])th of t)robably as 
much as BK) to feet out of a much older i^lain of which only 
flat to])ped ])ortions protected by a hard lateritic covering have 
survived. Quite similar cliffs wdth lateritic flat tops to them are 
seen again some miles north of Mertondale, high enough to receive 
special mention on the mat), and others near Wilson’s patch, on 
the high ground on the road from Lawlers to Lake Harlot before 
dro^iping down to the level of the lake plain, at Hells Gates some 
eight miles east of ^laninga Marley on the road from there to 
Lawlers, and a particularly good example at Walkinjerie, a little 
west of the read from Sandstone to Birrigrin. The Walkinjerie 
hill as it ap])ears from the plain, is a narrow plateau of weathered 
