ANDREWS : LIMESTONES OF THE FIJI ISLANDS. 7 



(c) Fiji "soapstone " with interstratified coral reef and coral detritus, 

 as well as one bed of coarse well-rolled pebbles of volcanic rocks. This 

 formation is at least three hundred feet thick, and its base is not visible. 

 It exhibits in places, as at Suva, a dip of about 10°. 



As you have ample material for a detailed description of this remai'kable 

 tufaceous marine mudstone, I will make only the few following remarks 

 about it : (1) That on certain horizons in Suva at over a hundred feet 

 above sea-level I noticed thin interstratified bands, almost wholly formed 

 of angular crystals of augite and plagioclase and of lapilli of decomposed 

 basic lavas, from the size of a hazel-nut to that of a walnut. There 

 appeared to me to be every gradation in this soapstone from a true sub- 

 marine tuff to a slightly tufaceous foraminiferal rock, and from the latter 

 rock into a tufaceous detrital coralline limestone. 



In one spot at Walu Bay a small coral reef is interstratified with the 

 soapstone, as already mentioned in your paper. 1 Professor Sollas has 

 referred to this as indicating that some, at all events, of the soapstone was 

 laid down in shallow water, and is not, as Mr. G. B. Brady maintained, 

 of rather deep-water origin. The coarse conglomerate formed of volcanic 

 pebbles at the base of the coral rock at Walu Bay confirms this view. I 

 observed a large clam-shell (Tridacna) at the rifle butts at Walu Bay 

 Quarry, and was shown large teeth of Carcharodon from this quarry by 

 Sir Henry Barclay. Mr. Andrews has forwarded you a similar Car- 

 charodon tooth. The evidence of these fossil sharks' teeth alone would 

 prove the formation to be at least as old as Pliocene, while the occur- 

 rence of Tridacna shows that it is referable to the later rather than to 

 the earlier Tertiaries. 



4. Raised limestones. These are formed, according to Mr. Andrews' 

 observations, only to a very limited extent of coral in situ, such as would 

 have formed a true coral reef. True coral reef limestone was usually 

 found forming a capping about one hundred feet in thickness at the top 

 of the raised limestone. Such is the case ki several places at Mango, and 

 also at Tuvutha, Thithia, and Kambara, etc. 



Much of this limestone has been elevated from 800 feet to 1050 feet 

 (Vatu Vara) above the sea. The base is usually not seen along the 

 seaward faces of the islands, except in the case of Mba Vatu and 

 Tuvutha and Mango. At Mango there is a good section a short dis- 

 tance inland, showing the limestone resting on a foundation of marine 

 calcareous rock with abundant fragments of decomposed basic or ande- 



1 American Jour. Sci., Vol. V., February, 1898. " The Islands and Coral Reefs 

 of the Fiji Group." By Alexander Agassiz. 



