388 W. G. WOOLNOUGH. 
-Coolgartie 
°Southern TOSS J 
Nullabor 
Plains 
In part, however, there isa real and fundamental differ- 
ence of level. So far as the observations of the author 
extend (and the Darling Range area has been fairly 
thoroughly traversed) these residual differences amount to: 
less than 200 feet in most cases, and this difference does. 
not appear excessive when the proviso that a peneplain is. 
not a mathematical plane is remembered. The present. 
height of the laterite surface is due to epeirogenic uplift 
of the whole area under discussion to the extent of the 
difference in altitude between the laterite-level and sea- 
level. A tilt as well as an uplift is at first suggested. 
When, however, it is considered that the difference in 
altitude between Coolgardie and the Darling Scarp is only 
600 feet, and the distance is about 300 miles, it is apparent. 
that the gradient of the surface must have been negligible 
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