BY D. MAWSON. 437 



Fiji are so extensively developed as to form the most important 

 horizon, after the limestones, outcropping on the island (see Sec. 3, 

 §1). They represent deposits of the finer material from the same 

 eruptions as were derived the coarser fragments of the associated 

 pumice tuffs. The differentiation is due partly to the varying 

 degree of buoyancy of the material causing the finer to settle 

 last, and largely to the fact that, subsequent to the sinking of 

 the denser pumice, a vast amount of fine powder would be con- 

 tinuousl}'' showered down, dei-ived from the attrition of extensive 

 fields of the lighter floating material. Several successive repeti- 

 tions or the passage of coarser into finer tuffs were noted, each 

 probably connected with a separate outburst. 



It is probable that beds in the upper part of the series owe 

 their origin to the later basic eruptions of Undine Fay and to 

 seas of floating pumice drifting from other localities. 



The fine-grained beds of the soapstone series are extremely 

 well bedded, contrasting strongly with the almost massive pumice 

 tufts; where the dip, undisturbed by faults, could be measured, 

 it was generally found to be a small angle in towards Undine Bay. 



Well in towards the centre of Efate, at Antonio's plantation, 

 where an outcrop of the soapstone was examined, an interbedded 

 band of calcareous rock"^ two feet in thickness, composed almost 

 wholly of tiny foraminifera and one specimen of Dentalium, was 

 noted; this find is of special interest, as it was the only locality 

 where fossils other than Globigerina were found in the soapstone. 



For the most part the soapstones are fossiliferous and only 

 slightly calcareous, the materials contributing to their forma- 

 tion being chiefly glass fragments and to a less extent mineral 

 fragments, chiefly felspar. Often amongst the finer soapstones 

 occasional rounded pellets of white pumice are to be found, 

 evidently representing water-logged particles. 



* Mr. F. Chapman, to whom a slide of this rock has been forwarded, states 

 that it contains no forms such as would definitely fix its age. The absence 

 of the larger forms like Lejndocijclina, he thinks, refers it to a later period 

 than the Miocene. 



