440 E. C. ANDREWS. 



Wales, where the geological structures are relatively weak. 

 In Monaro, New England, in the paheozoic areas west and 

 south of the Blue Mountains, and in other localities vast 

 areas of plateau exist which have not been dissected as 

 yet by the formation of the deep canons which sprang into 

 being when the plateaus were formed by faulting and Hex- 

 ing activities. The general appearance of the profound 

 canons of eastern Australia is similar to that of the Merced 

 example in California, while the Grand Canon of the Colo- 

 rado is only a larger example of plateau dissection by 

 streams. The plateaus of the Rocky Mountains, the Sierra 

 Nevada and of other localities in North America are not 

 more dissected by canons than are those of eastern Aus- 

 tralia. Nevertheless, literature is full now of descriptions 

 of the closing Pliocene 1 or even Post Pliocene" Age of this 

 plateau dissection in North America. From physical prin- 

 ciples" the age of our eastern Australian plateaus may also, 

 by analogy, be placed at the close of the Pliocene. 



and most immature in the region of the great fault blocks. 

 It may be interesting to see how youthful is the stage of 

 plateau dissection in eastern Australia by a reference to 

 the early history of the colonies. 



For many years the inland area remained unknown to 

 the early English colonists of New South Wales and Queens- 

 land. Time after time they attempted to force a way 

 across the Main Divide, only each time to be baflled by the 

 great sandstone, granite or slate ramparts which stretched 

 away "illimitable to the horizon/' The English brought 



