174 THE BUILDING OF EASTERN AUSTRALIA 



ranges. Bends concave to the east occur where areas 

 of soft Mesozoic sediments or Permo-Carboniferous rocks 

 have offered an easy task to the forces of erosion. The 

 ranges consist largely of barriers of hard palseozoic rock^ 

 whose directions of folding offer no clue to the tertiary 

 direction of pressure. 



It seems, therefore, that in the East Australian area 

 we cannot deduce the direction of earth pressures from 

 either the curvature of mountain ranges or from the fold 

 lines in the Palseozoic rocks, but only from the differential 

 movements of fault blocks. 



The existence of the high plateaux along the eastern 

 rim of the Continent seems to the writer evidence for 

 believing that the pressure came from the east. The greatest 

 uplift would be in the blocks in closest proximity to the 

 source of pressure. Experimentally this may be verified 

 by pushing a piece of paper away from you while the other 

 end of the paper is clamped under your inkpot. At first 

 it will fold upwards at the end from which the thrust is 

 exerted, then another fold appears near the object offering 

 resistence to the thrust and finarlly the whole sheet is 

 uplifted. If you try to fold a slightly elastic yet brittle 

 object in the same way, it will fracture before the first 

 fold (that near the source of thrust) is complete. Con- 

 sequently the block faulting in Eastern Australia, along 

 the Pacific rim, is further evidence for deepseated pres^ 

 sure from the East. 



Where least resistance was offered to the thrust by 

 Palaeozoic massives, the main uplift was further from the 

 source of pressure. This will account for the wide expanse 

 of lowland country between the Darling Downs and Moreton 

 Bay. 



The writer is, therefore, not in agreement with Mr. 

 Andrews' deductions regarding lines of pressure. Prob- 

 ably his lines of pressure from the Southern Ocean towards 

 the interior of Australia are correct, but his lines of pressure 

 from Eastern Australia towards the Tasman Sea should 

 probably be reversed. [23] 



In 1902 [23], Andrews attributed the rugged nature 

 of the North Queensland coast to recent faulting. In 

 the writer's opinion, this view is corroborated by the fact 

 that the Barrier line of reef is separated from the coast 



