Agassiz — Tertiary Elevated Limestone Reefs of Fiji. 165 



Art. XY. — The Tertiary elevated Limestone Reefs of 

 Fiji ; by Alexander Agassiz. 



Dr. William H. Dall has been kind enough to examine 

 the fossil mollnsks which I collected from the elevated lime- 

 stone reefs in Fiji. He confirms the impression I had formed 

 of their late Tertiary age. 



Dr. Dall writes : " The fossils comprise Turbo, Cassis, 

 Lithophaga, Macha, Tellina, Meretrix, Dosinia, Chama, Pholas 

 and fragments of Pecten. None of the genera are extinct. 

 The rock, however, looks decidedly too old for Pleistocene. I 

 should say the fossils were younger than Eocene and might be 

 either Miocene or Pliocene." 



The boring which I started at Wailangilala Island in the 

 atoll of the same name, was only carried to a depth of 85 feet. 

 For 40 feet the tool passed through coral sand similar to that 

 forming the shores of the island ; from that depth down to 85 

 feet, the core consisted of a limestone similar in all respects to 

 the limestone composing the elevated reefs we had observed at 

 Ngele Levu, at Yanua Mbalavu, at Mango, at Yangasa, at 

 Oneata, at Ongea, at Kambara, at Yatu Leile and at different 

 points along the eastern, southern and western shores of Yiti 

 Levu. As at some points the elevated limestones attain a 

 height of over 1000 feet (Yatu Yara Island, 1030 feet), noth- 

 ing could be gained by continuing the boring at Wailangilala 

 to obtain material which could be collected so readily in other 

 localities ; the boring was therefore abandoned. 



The volcanic rocks underlying the elevated limestone reefs 

 were observed at Yanua Mbalavu, at Mango, at Kambara and 

 at several points along the southern and western coast of Yiti 

 Levu. To have continued to bore until we should strike the 

 underlying rocks would have been equivalent to boring in 

 localities where the base of the limestones had been but little 

 elevated when it could be readily examined in the localities I 

 have mentioned. 



A renewed examination of the elevated reefs of the Pau- 

 motus, of the Friendly Islands, of the Gilbert, Ellice and other 

 groups of atolls in the Pacific, will be needed to determine 

 their age and correlation to the Fiji elevated limestones. 



At any rate it is evident that the Tertiary coralliferous lime- 

 stones of Fiji have not played any part in the formation of the 

 atolls or islands encircled by recent coral reefs, beyond form- 

 ing the substratum upon which the recent corals have grown 

 and established themselves as a comparatively thin crust. 



The underlying limestones have performed exactly the same 

 part as the volcanic substratum in other islands of Fiji, such 



