president's address. 565 



The five last named rocks, though placed as the lowest in 

 position, and often found as such, are all younger than the lowest 

 of the above-mentioned sedimentary rocks. At aJl events we have 

 as yet no evidence to the contrary ; for wherever the boundaries 

 of the Silurian and granites are well indicated, the latter are 

 observed to be metamorphosed beds of the former ; and where the 

 metamorphism has been so great as to have produced semi-fluid 

 conditions, the granites are seen as intrusive masses penetrating 

 the Silurian rocks. T have seen in New England instances of 

 metamorphic granites and porphyries in which the lines of strati- 

 fication of the original sedimentary formation have not been 

 obliterated ; and also, in the same locality, splendid sections 

 shewing intrusive dykes and masses of these rocks. The diorites 

 in like manner have penetrated the Carboniferous rocks ; and 

 some of the basalts have in places burst through and overflowed 

 all the formations older than the Pleistocene. 



The connection of the older igneous rocks with the sedimentary 

 formations which have been affected by them has had an important 

 influence upon the occurrence of some of our economic minerals. 

 Thus some of the richest deposits occur only where the Silurian 

 and Devonian formations have been disturbed by intrusions of 

 diorite ; and the bismuth lodes, also many of the tin lodes, traverse 

 the granite near its junction with the slates ; I shall again make 

 reference to these further on. 



Coal. 

 New South Wales is rich in coal, shale, gold, tin, copper, iron 

 and antimony, but of these coal, the value of the annual produc- 

 tions of which now exceeds that of any of the others, may justly 

 be considered of the greatest national importance, and in its 

 development lies the establishment and success of various com- 

 mercial industries. Fortunately our coal deposits are very 

 extensive and are available in widely separated localities both 

 upon the seaboard and inland. Sydney is situated almost in the 

 centre of a great coal basin, the eastern half of which long ago 

 sunk down and disappeared beneath the ocean, the present coast 

 marking the line of fault. But we can well excuse this fault, for 



