[Pkoc. Roy. Soc. Victoria, 31 (N.S.), Part I., 1918]. 



Aht. Vf. — The Sand Ridges, Rock Floors, and other Associated 

 Features at Goongarrie in Sub-arid Western Australia; 

 and their Relation to the Groivth of Lake Goonga/rrie, 

 a " Dry " Lake or Play a. 



By J. T. JUTSON 



(Geological Survey of Western Australia). 



(With 3 full page illustrations). 

 [Read June 13th, 191 8]. ^ 



Introduction. 



Goongarrie is a small mining township fifty-five miles north of 

 Kalgoorlie, on the railway from Kalgoorlie to Leonora. Its height 

 above sea-level is 1277 ft., and it is situated on the Great Plaeau 

 of Western Australia, where the climate is sub-arid and the rainfall 

 slightly under ten inches per annum. The conditions therefore are 

 not such as obtain under " normal " erosion; and as the topography 

 appears to be unique and indicates to some extent the respective 

 roles of wind and water erosion in sub-arid Western Australia, this 

 paper is submitted. 



Summary. 



The southern portion of Lake Goongarrie, a ''dry'' lake or 

 playa, is described. It possesses dissected '' high " lands, " low- 

 lands," piedmont plains (some of which are truncated by low cliffs), 

 rock cliffs, rock floors and small shallow rock basins on or towards; 

 its western side, with sands and silts on the eastern. In addition^ 

 there are small " islands " and " peninsulas," which are chiefly 

 sand ridges, towards the western side. Between the sand ridges, 

 which run approximately east and west, are narrow arms of the 

 lake, w^hich are rock-floored in their western portions, and tend t» 

 be silt-covered in their eastern portions. 



Water action has cut the valleys in the hard rock of the " high " 

 lands; it is mainly responsible for the " lowlands " by the cutting- 

 back (westward) of softer rocks; and also for the piedmont plains 

 at the foot of the steep cliffs. The action of the rain has l^een 



1 By perminni»>n of the Actinjf Government GeoloffiHt of Western Australia. 



