428 Correspondence — ITr. R. Etheridge, Jun. 



coiE^S/iESiPon^rnDEn^ciH]- 



NOTES ON THE GEOLOGY OF NEW GUINEA. 



Sir, — From tlie interest which has of late been taken by the 

 public in matters relating to New Guinea, the following geological 

 notes may be of interest. 



I have been favoured by my friend, Mr. C. S. Wilkinson, Govt. 

 Geologist, N. S. Wales, with a newspaper slip containing an abstract 

 of a paper by himself, read before the Linnsean Society, Sydney, 

 28th February, 1876, Notes on a Collection of Geological Specimens 

 collected by W. Ilacleay, Esq., from the Coasts of New Guinea^ Cape 

 Torh, and Neighbouring Islands, from which I take the following. 

 The specimens upon which Mr. Wilkinson lays the greatest stress 

 are Oolitic Tertiary Limestone from Bramble Bay, yellow calcareous 

 Tertiary clay from Katan Eiver, and yellow and blue ditto from Yale 

 Island and Hall's Sound. These clays, from the evidence afforded by 

 the contained fossils, Mr. Wilkinson considers to be Lower Miocene, 

 and, he says, are exactly similar in lithological character to the Lower 

 Miocene beds near Geelong and Cape Otway, Yictoria. The clay 

 from Hall's Sound contained at least two Victorian species, Voluta 

 macroptera, M'Coy, and V. anto-cingulata, M'Coy, with species of 

 Ostrea, Cythercea, Crassatella ?, Pecten, Turritella, JVatica, Triton ?, 

 Dolium ?, Astarte, Corbula, Lceda, Venus, Cyprcea, and two Echino- 

 derms. The calcareous clay from Katan River, west side of the 

 Gulf of Papua, contained only a few broken shells ; but both it, and 

 the Oolitic Limestone of Bramble Bay, Mr. Wilkinson believes to be 

 of the same Miocene formation. This is very interesting from the 

 fact, that hitherto no Miocene Tertiary beds have been met with 

 in the East of Australia farther north than the boundary between 

 Victoria and N. S. Wales — although they are highly developed in 

 the former and S. Australia, extending westwards towards W. 

 Australia. According to Macleay and Signer D'Alberti, Yale Island 

 is formed of a calcareous sedimentary rock, dipping inland and 

 composed of Corals, Shells, and Echini. In the valleys trap is found, 

 and the higher portions of the hills, which attain a height of 700 to 

 800 feet, are composed of Coralline Limestone. Mr. Wilkinson con- 

 siders that the occurrence of these beds, which he believes to be 

 Miocene, in New Guinea, suggests the former land-connexion of the 

 latter with Australia, the shallowness of the intervening Torres 

 Straits lending additional weight to this view. Tertiary rocks 

 described by Mr. Macleay as existing at Cape York, especially a 

 ferruginous sandstone overlying the porphyritic granite of that 

 locality, may be perhaps correlated with these New Guinea beds. 



Edinburgh. R. Etheridge, Jun. 



APPAEENT AND TRUE DIP. 

 Sir, — In reference to the subject of Apparent and True Dip, 

 attention might be redirected to Mr. Dalton's " Geological Problems," 

 published in the Geological Magazine, Vol. X. p. 332. 



H. B. W. 



