99 



and Yili^arn, and also between Golden Valley and the country 

 around Mount Churchman. They occur in belts or patches 

 between the sand-plains, and are often 10 to 20 miles across. On 

 account of the scarcity of vegetation, they represent a very dismal 

 aspect. 



The " crust limestone" or travertine, is of comparatively rare 

 occurrence. It is limited to the beds of watercourses, and is 

 found there only in very moderate thickness. In a creek near 

 the Waterhall Mine, at Golden Valley, it was found exposed to a 

 thickness of two feet. 



Salt Lakes. — All over this portion of the country \\'ere 

 encountered numerous and extensive, what are generally styled, 

 " salt lakes," to which reference must here be made. In a former 

 chapter I essayed to explain the terrestrial origin of some of the 

 salt lakes in or near Mesozoic deposits ; but such origin is not 

 applicable to the salty claypans of the West Australian high 

 plateau. There is little doubt that these large flats, covered with 

 efflorescent salts, represent depressions of the granitic upland, 

 in which the saline matter remaining from isolated, and in due 

 course of time evaporated, parts of the ocean, has been accumu- 

 lated. As they have no outlet at all, or only one at a very high 

 water-mark, the saline matter remains, and a proof that this 

 granitic upland has been raised from below the level of the sea, 

 the widespread occurrence of the sandstone cappings of these 

 granitic rocks may be adduced. 



These wide lake-basins are surrounded either by large clay- 

 flats or, as it was found in the southern portion of this section, 

 by low clifi's consisting of a hard silicate of magnesia-rock. This 

 formation signifies most likely ancient deposits of these lakes. 



As a minor feature, may here be mentioned deposit's of quano 

 in caverns and rock-holes of the numerous granite rocks of this 

 country, which have most likely accumulated there through bats 

 and wallabies using them as shelter. 



" Desert Sandstone." — As a transition to the older formations 

 we may be regard the sandstone which caps tlie crystalline hills, 

 especially in the more northern parts of this section. This 

 formation was encountered firstly when descending towards the 

 Warne Flats, which are bordered also to the east and north by 

 hills of the same formation. This sandstone overlies directly the 

 granite, and is invariably horizontally-bedded ; its thickness 

 varies from about ten to 200 feet on the hills round Mount 

 Kenneth. As the lower jDortions of this sandstone are more iir- 

 clined to weathering than the upper, these form overhanging 

 escarpments, with numerous caves at the base of them. Big 

 hungry-looking quartz-blows in these sandstone deposits occur 

 frequently, being only infiltrations of siliceous matter, as they 



