330 REPORTS OF RESEARCH COMMITTEES. 



the Kimberely Peneplain, and the North- West Peneplain. The 

 views as to the date of peneplanation and of viplift have been 

 stated under " Old and New Plateaux." W'oolnough (44) accepts 

 the Darling Peneplain, and suggests that there is an older pene- 

 plain represented by residuals, which he terms the " Mount Dale 

 i^evel " ; and that a lower level, the " Meckering Level," repre- 

 sents a carving of mature valleys in the Darling Peneplain after 

 thei latter had received a small elevation. Subsequent greater 

 uplift resulted in the present erosion below the Meckering Level. 



5. liATERiTE — Its Physiographic Significance. — Woolnough 

 (43, 45) holds that the laterite, which widely covers the surface of 

 the great uplifted peneplain of Western Australia, was formed 

 on the completion of penej^lanation of the Darling Peneplain and 

 before uplift, and in this way laterite-capped plains at markedly 

 different levels may suggest block-faulting, aiii example of which 

 is the possible step-faulting associated with the main Darling Fault 

 Scarp. 



6. Evolution of River Systems. — Jutson (14) treats of this. 

 The interior draina!>e is dealt with under the " Dry Lakes." The 

 exterior is divided into that of the Kimberley, the North- West, 

 and the South- West divisions. The Kimberley division is shown "by 

 Jutson to have a radial drainage from Mt. Hann. The streams 

 are frequently transverse, with abundant water-gaps. Longitudi- 

 nal streams may have ciaptured some of the transverse. The most 

 noticeable feature of the streams of the North- West is the numerous 

 water-gaps, which, by their relations to the surrounding country, 

 indicate that the streams are not antecedent in the sense that the 

 ridges have been elevated as the streams cut through, such ridges 

 being duei toi differential erosion. In the South-West (Swanland), 

 Jutson suggests (12, 14) that the main drainage was originally 

 marginal, but that this was largely broken and replaced by radial 

 drainage. Woolnough (44) agrees in general with, but differs in 

 detail from, Jutson on this question. Taylor (38), in accounting 

 for the rectangular character of many of the streams, suggested 

 that the rivers originally flowed south-westerly, but that later 

 tilting to the north-west strengthened the westward-flowing streams. 



7- Scarps. — Jutson (14) divides the scarps into fault scarps and 

 erosion scarps. Fault scarps he subdivides into revived fault 

 scarjjs and normal fault scarps. The previously recognised Darling 

 Fault Scarp' is regarded by him as a revived fault scarp. Among 

 possible normal fault scarps mentioned by him are the Great Bight 

 or Bunda Scarp, the Hamersley, and West Pilbara scarps. The 

 Naturaliste Scarp (the later Naturaliste-Leeuwin Scarp of Wood- 

 ward) was previously suggested by Saint-Smith as a fault scarp. 

 Jutson divides erosion scarps into normal erosion scarps (an exam]>le 

 of which is the Kennedy Scarp), and fault-line scarps (examples 



