196 ON THE GEOLOGY AND PETROGRAPHY OF BATHURST, N.S.W., 



granite to be the result of extreme metamorphism, as possibly 

 some granites are, but in studying the geologj' - of Bathurst one 

 soon abandons all hope of maintaining such an origin for the 

 granitic mass as a whole. This will be dealt with further on. 



Wherever I have studied good junctions I always noticed that 

 the slates are cut off suddenly by the granite, and in no instance 

 have I ever seen a slate rock resting on a granitic floor in a way 

 that would suggest it was originally laid doivn there. Indeed, no 

 idea can now be formed of what may have been the character of 

 the old sea-bed on which the sediments were first deposited. No 

 trace or vestige of it remains. The granite behaves in every 

 respect as a rock that was erupted into overlying slates, and is, 

 therefore, the newer. Slate, then, we take to be the most ancient 

 formation. Next in age come the granites. The overlying 

 Devonian rocks are, of course, more recent than either. 



From the character of the material forming the great bulk of 

 the slates, we can surmise that the rocks were formed on a deep 

 sea-bottom. The margins of any sea-bed would naturally be made 

 up of coarser material. Rocks, corresponding to these deposits, 

 are abundantly represented. The lines of limestone had an origin 

 not unlike the coral reefs of our own day. The proximity of lime- 

 stone to conglomerates points to the presence of a shallow sea or 

 sea-beach. The old silurian ocean had its lines of coast, and 

 there must have been a continent at no great distance off, the 

 wearing down of which supplied the material to form the rocks 

 we are discussing. In what direction did this continent lie 1 

 What was the nature of its rocks 1 Has it disappeared to its very 

 foundations 1 These are questions, full of interest as they are to 

 the geologist, to which no satisfactory replies can be given. 



The onlv formations resting on the granites and slates are the 

 drifts- These are all of tertiary and post-tertiary age. Between 

 these two widely separated formations there exists an immense 

 interval, regarding which the rocks of Bathurst contribute nothing 

 to our knowledge. It is difficult to think that no other rocks, 

 Devonian, Carboniferous, or Jurassic, ever existed above where 



