BY B. SAWYER AND E. C. ANDREWS. 101 



Water trickling down and from the roof allows of an infinitesimal 

 amount of evaporation. This is, however, sufficient to permit of 

 a tiny deposit of carbonate of lime on the roof or Hoor. These 

 deposits, as time goes on, take on the form so common in cave 

 scenery, such as stalactitic, stalagmitic and shawl-like growths. 



2. Origin of the Viti Levu Caves. — These are very probably 

 due to agencies which determine cave-formations generally, as 

 described in the preceding paragraph, 



For the limestones in which they occur both at the mouth of 

 the Singatoke River and 25 miles higher up the stream show 

 bedding planes as pronounced as those of the Hawkesbury sand- 

 stone, and, with the exception of a single intercalated coral reef 

 and a few scattered fragments, are utterly devoid of coral growths. 

 They are also of sandy nature, after the fashion of compacted 

 braches, and are thus composed of waste sheets. The cave also 

 in the limestone at the Singatoke mouth follows the bedding of 

 the strata for long distances, and contains very thick deposits of 

 mud on the floor. 



These observations point to formation subsequent to the lime- 

 stone deposition, although it is possible that the initial stages 

 were determined by submarine agencies, post-dating the forma- 

 tion of the strata. 



3. Origin of Lan Caves — These appear to be moulded on 

 lines totally different to those obtaining at Viti Levu. Whereas 

 the majority of caves owe their existence to hypogene agencies, 

 it seems more feasible to refer the origin of the typical Lau 

 caverns to submarine action modified to minor extent only by 

 hypogene influences. 



It may not be generally known that the greater number of 

 modern " reefs," such as those of Fiji, are composed of coralline 

 debris, foraminiferal tests, echinoderms, mollusc shells and vast 

 quantities of calcareous alg?e (such as Halimedai and Nullipores). 

 Calcareous matter is also deposited between the tiny interstices of 

 these fragments until the mass assumes a homogeneous appearance. 



On the seaward edge of these, however, luxuriant coral and 

 nullipore growths occur. It is also very common in the lagoons 



