•86 



NOTES ON THE GEOGRAPHY OF THE BLUE 

 MOUNTAINS AND SYDNEY DISTRICT. 



By E. C. Andrews, B.A. 

 (Plates xxxix.-xliv ) 



Introduction. 



The following notes are intended merely as an introduction to 

 the geographical study of the Blue Mountain area. The salient 

 points of the subject only are touched upon, the details being 

 problems for future study. The deductions themselves also are 

 suggestions only, needing more extended inductive studies for 

 confirmation. 



For a brief outline of the process involved in stream develop- 

 ment, reference may be made to a paper by the writer* on "The 

 Tertiary History of New England," in which the views of the 

 American geographers are epitomised. To Hutton and Playfair, 

 of England, the pioneering of this branch of study is due; but 

 they lived a century in advance of their age, and stream develop- 

 ment received little attention for a considerable period after their 

 deaths. Sir A. Geikie recognised the importance of their 

 methods more than half a century later, while J. W. Powell, J. 

 S. Newberry, and others, as the result of exploration in the 

 wonderland of the Western States of America, readily appre- 

 hended the natural succession of the forms induced by the 

 agencies of gradation in elevated areas. To the untiring labours 

 of Prof. W. yi. Davis and his lucid interpretation of surface 

 forms, modern geography owes probably its greatest impetus. 

 As Prof. Huxley to the theory of biological evolution, so Prof. 



* Records Geol. Survey N.S. Wales, vii. Pt. 3, 1903, pp. 1 40-216 (and 

 references). 



