Merced, the Colorado and the Arkansas are generally 

 assigned to the Ozarkian or Sierran Period (Pleistocene of 

 Le Conte and others). 



(d) The igneous and sedimentary complexes out of which 

 the western Nortli American ami eastern Australian sur- 

 faces have been excavated, are almost identical in chemical 

 and physical properties. 



(e) The laws of hydrostatics and hydrodynamics have 

 been identical both in Australia and in America during 

 Tertiary and post Tertiary time. 



(f) The main agents of erosion have been the same in 



(g) The amount of rainfall, the variations in heat and 

 cold as well as the other physical phenomena involved in 

 each area have been comparable from a quantitative point 

 of view during Pliocene and post Tertiary time. 



(h) The flood stream has been, and is, the main agent in 

 I rock structures the world over. 



Therefore if a peneplain has been formed near sea level 

 over the western side of the North American continent 

 during Tertiary time, it is legitimate to consider that a 

 peneplain could also be carved out of Australia during the 

 same time. A closing Tertiary age may be assigned to the 

 great plateau formation, the fault scarps therein and the 

 profound gorgeswhichhavecuttheirwaysinto the tableland. 

 Additional evidence of the late or post Tertiary age of the 

 plateaus and gorges is presented in the body of the report. 



The writer here desires to acknowledge the great help 

 he has received from a perusal of the works 1 of David, 

 Baron von Mueller, Murray, Wilkinson, McCoy, Came, 

 Hedley, Skeats, Jensen, Hall, Chapman, Gregory, Siissmilch, 

 Cambage, Maiden, Deane, and others in the preparation 

 of this report. 



