100 NOTES ON THE CAVES OF FIJI, 



Every island navigator is familiar with the deep clefts in the 

 fringing reefs of the shallow Somo Somo Strait at Taviuni. 



A characteristic feature is the arched appearance they fre- 

 quently present to the sky, having narrow openings at water 

 level, and a series of wider anastomosing canals below. 



Now, in Vatu Leile, as explained in a previous paragraph, we 

 have caves partly under and partly above water, the whole 

 appearance being that of a series of chambers with a few narrow 

 passages opening upwards and outwards to the sky. 



Near Tuanuku, in the Vavau Group (Tonga), a beautiful cave 

 exists in the raised limestone. This also is half-submerged, yet 

 of such a size that we sailed a cutter, with mast up, right into 

 the cavern. The highest part of this chamber must have been 

 70 feet above water level, and the water inside the cavern was of 

 equal depth. This chamber was connected with others V)y pas- 

 sages, and opened to the sky by a small hole. 



It seems that here we have a condition of things attainable by 

 suddenly raising the present fringing reefs of Kambara and Vatu 

 Vara, so as to leave the crevasses and chambers half submerged. 



E. — 1. Description of Cave-Formation generally. 



Acidulated water (deriving its acidity from decaying vegetation, 

 tfec.) trickling over limestone, attacks the rock mass, carrying it 

 away, little by little, in solution. In this way, by attacking the 

 rock along the joint-planes, swallow- and sink-holes are formed 

 in the limestone mass. These, after a time, may become united 

 at a depth through the continued action of the percolating 

 waters. Eventually a subterranean watercourse is formed, and 

 the shape of the excavation is that of a series of chambers united 

 by tortuous passages. 



When a cave has been excavated, the water still eats into the 

 the stone, and other sink-holes being formed below its level, the 

 old stream bed is deserted in favour of a newer and lower one. 



The process of refilling now sets in at the upper level. 



