BY D. MAWSON. 453 



hand, with a general dip inwards to the land side. Near 

 C. Karai they are intruded by a glassy hypersthene andesite. 



In the Puria Etsa district agglomerate beds are developed 

 apparently underlying the bedded Miocene series. 



In this promising locality beach and river pebbles were 

 diligently examined in the hope of finding traces of the gneiss 

 reported to be largely developed in this locality. The search 

 proved fruitless, however; the only rock-type discovered not 

 already found, occurring in situ, was a pebble of a biotite 

 hornblende andesite. 



Sec.3. PETROLOGICAL DESCRIPTIONS. 



i. Efate Soapstone s. — Under this title are grouped a 

 variety of fine-grained submarine tuffs, so named on account of 

 the resemblance which typical specimens bear to the well-known 

 Fiji Soapstone. They are well bedded, differentiated into 

 alternating coarser and finer bands, the former of which occa- 

 sionally pass over into a coarse pumice tuff. Endless varieties 

 are further produced by the introduction of varying quantities 

 of organically derived calcium carbonate which is present usually 

 as Glohigerina tests, though in one locality quite a variety of the 

 smaller forms of the foraminifera were observed. 



Distinctive features of these beds are softness, friability, earthy 

 odour, greasy feel of the finer samples, and, above all, marked 

 absorptive properties. If a dried sample be placed in water it 

 immediately sinks, and, as it continues to absorb moisture, streams 

 of tiny air bubbles are given off, accompanied by a fizzling sound. 

 In the case of the yellowish samples (the most greasy and 

 probably the more basic) subsequent drying, even slowly in a 

 normal atmosphere, causes them to crumble up. 



In colour they vary from a pure white to shades of yellow and 

 grey, usually ashy-grey. Brown manganese stains are sometimes 

 observed, more commonly along the joints. Apparently homo- 

 geneous samples will as a rule, on more careful examination, 

 be found to contain coarser and finer bands often only a few 

 millimetres thick. These finer bands represent material of the 



