14 president's address. 



that the abyss beyond the margin of the continent is a pres- 

 sure-trough. 



If it be really such and if it can be correlated with great 

 earth-folds that swell in New Caledonia and New Zealand, 

 then its effects should be discernible in the face of Australia. 



Fig. 1. — Diagram showing relation of the New Zealand ridge to the 

 Ulladulla trough. 



The term "fold" is here employed in the broad sense in 

 which it is used by Professor C. Lapworth in his Presidential 

 Address to the British Association.* From Hobart to Thurs- 

 day Island the whole Pacific coast is acknowledged to have 

 undergone recent and considerable subsidence. It is l-.ere 

 suggested that this subsidence was effected by compressive 

 movement, and that this is demonstrable by the inward 

 crumpling of the land. The argument that follows seeks to 

 show that the abnormal and distorted rivers, so peculiar a 

 feature of this coast, are a consequence of this cause. 



The best studied section of the East Australian coast, that 

 through Sydney, exhibits a magnificent fold in which the 

 coal seams rise in a wave curve in seventy miles from three 

 thousand feet below the sea to three thousand feet above it.f 

 As the coal plants grew in a great swamp, or series of 

 swamps, so the coal beds must have extended horizontally 

 during their formation. Being a fresh-water deposit, it was 

 clearly above, though not much above, the level of th^ sea. 



* Report Brit. Assoc Edinl)urgh, 1892, pp. 695-707. 

 t Came, "Geology of Western Coalfields," 1908. Plan opp. p.l60. 



