85 
quarters of a mile Jong. The depth of the bottom of the lagoon below the 
surrounding country does not exceed 4ft. or 5ft., and as there was at the time 
it was visited not more than 3ft. of water in it, it was already in process of 
drying up. Where dry the bottom was seen to be formed of a clayey sand. 
Conlon Lagoon lies between two ranges trending-east and west, the drainage 
from which finds its way into the lagoon. There is, however, no indication of 
an outflow eastwards to the Todd {the only possible direction), the lagoon and 
the ranges on the north and south forming a miniature internal drainage system 
of their own. 
F.—STONY PLAINS. 
The whole of the area from the northern extremity of Flinders Range north- 
wards to within a few miles of Mount Burrell cattle station on the Hugh river, 
and for mary miles in an easterly and westerly direction, may be said to be 
occupied by rocks of Cretaceous age, covered over large areas by Post-Tertiary 
deposits and over very limited areas by Pliocene beds of lacustrine origin. The 
upper strata of the Cretaceous system have been removed by denudation over 
extensive areas, the remaining portions being in the form of more or less isolated 
table-topped hills dotted about throughout the whole area. The materials set 
free by this denudation have gone to form the superficial accumulations known 
as ‘‘ gibber’’ or ‘‘stony plains,’’ loamy plains, and to a iarge extent also the 
sandhills. 
‘Stony plains’’ is the name given to those portions of the Cretaceous area 
over whose surface are strewn ‘‘ gibbers,”’ i.e., rounded or sub-angular fragments 
of silicified sandstone or grit known as ‘‘ Desert Sandstone.’’ The Desert 
Sandstone is extremely hard and weather-resisting, and has a somewhat sub- 
conchoidal fracture. With such properties it is not surprising to find fragments 
of it covering much of the country from which the sandstone has been denuded. 
The uniform distribution of the gibbers, which is a very characteristic feature 
of this class of country, is due to the fact that the fragments derived from the 
layer of ‘‘ Desert Sandstone’’ which extended over this area, now strewn with 
gibbers, have not undergone redistribution to any largedegree. Ina flat district 
like this the surface water has not been able to sweep them into watercourses. 
The removal of the argillaceous sand by the wind and rain has permitted the 
gibbers to settle down, until in many places they present a flat surface resembling 
an artificial pavement. The outer surface of the gibbers is of a dull red color, 
due to the presence of a thin film of oxide of iron coating them. They also 
present a glazed sub-angular or pseudo-waterworn appearance, produced by the 
polishing action of the sand grains as they are driven along the surface of the 
ground. 
The stony plains gradually merge into loamy plains, which possibly occupy 
the sites of areas of the Upper Cretaceous, which were devoid of the ‘‘ Desert 
Sandstone ’’ capping. 
On either sides of the banks of many of the rivers, especially along their 
serpentine courses over the plains, are extensive alluvial plains. During floods 
the channels are too flat and shallow to carry off the immense body of water 
that occasionally comes down them, and the water spreads out on either side, 
sometimes for miles. The “box flats,’? which are met with on the sides of 
the Finke Channel, are flood plains, on which Eucalyptus microtheca flourishes 
in large numbers. 
b) 
