[Pboc. Eoy. Soc. Victoria, 32 (N.S.), Pt. I., 1919]. 



Art. IV. — On the ^' Claiving" Action of Rain in Sub-Arid 

 Western Australia. 



By J. T. JUTSON 



(With Plate II.). 

 [Read 10th July, 1919]. 



Introduction. 



In sub-arid south-central Western Australia, which is portion' 

 of the great plateau of that country, erosion presents results dif- 

 ferent in many ways from those obtained in areas possessing a 

 " normal " climate. Thia is partly due to the difference in degree,, 

 and to some extent in kind, of the erosional agents, and partly to 

 the surface alteration that rocks and soils have in many parts 

 sustained. There are certain minor featui^es •which are peculiar to 

 the area, and therefore of interest. Such are the miniature soil- 

 terraces described in this paper, the formation of which is asso- 

 ciated w'ith the "clawing" action of rain, and with the gravita-- 

 tional drift of rock debris. 



Summary. 



The " clawing " action of rain on gentle soil-covered slopes with 

 a firm surface produces terraces with tiny cliffs, which are termed 

 " miniature soil-terraces," and at the same time gradually removes 

 the soil to loAver ground. By the formation and recession of these 

 terraces, drifting rock debris is undermined, and topples forward 

 dow'n the slopes. Thus a decided aid is given to the slow, gravita- 

 tional drift of rock debris from higher to lower parts. 



Description of the Processes. 



In sub-arid south-central "Western Australia there is a wide- 

 spread tendency to form hard caps at the surface, owing to water- 

 Ijeing drawn there by capillary attraction, and to evaporation then 

 taking place with deposition of the contained salts. 



Soils are no exception to this process, although the cap is in 

 places but a mere film of slightly firmer material than that below. 

 This film, however, is quite sufficient to influence the transporting 

 action of the rain. On many gentle soil-covered slopes, especially 



