4 IN THE BLUE MOUNTAINS 



any great body of water in any of these remarkable 

 recesses. In valleys which are from six to fifteen miles 

 wide, I have found the strata of the opposite sides 

 corresponding exactly, and of almost precisely the same 

 height : while the bottoms of the valleys are level, or 

 nearly level, plains, with occasionally a few scattered hills. 

 There are no signs of water-wear, nor of the subsidence 

 which Darwin thought might be a possible explanation 

 of this unparalleled formation ; and I think it is a pity that 

 he did not devote more time and care to the examina- 

 tion of what he rightly recognised and described as a 

 geological enigma ; but which he unfortunately seems to 

 have viewed with an impatience unusual in him. 



Some of these enclosed valleys in the Blue Mountains 

 have an area of more than a hundred square miles, with 

 a depth of nearly two thousand feet, and yet have no 

 opening through which the water of a small brook could 

 escape. In a country with a fairly heavy annual rainfall 

 these valleys would inevitably become deep lakes. Can 

 they possibly be the beds of long extinct lakes, the waters 

 of which have gradually soaked and evaporated away 

 through some change of climatic conditions causing a 

 cessation of the usual feeding supply? It is more likely 

 that these valleys are the result of upheaval than of sub- 

 sidence, and they may, at a remote period, have been 

 saline lakes. Marine shells are very abundant in many 

 places, but I have not found any other important remains 

 that are likely to throw a light on the geological formation. 

 Though many of the shells are of extinct species, a great 

 number are identical with those still inhabiting the seas 

 of the west and south coasts. 



The vegetation of the valleys, if not rich, is abundant, 

 and the forests are certainly valuable. Cattle thrive well 

 in them, and they serve the purpose of immense parks 

 from which it is impossible for the stock (as cattle in 

 Australia are invariably called) to escape. The trees are 

 no impediment to the grazing of cattle: for though the 

 forest, viewed from above, appears to be dense, but few 

 Australian forests have the density of tropical or European 





