ANDREWS: LIMESTONES OF THE FIJI ISLANDS. 35 



(Plate 7) more than a mile in length and exceeding a height of 300 feet, 

 the rock is stratified, and dips at a uniform angle of 15°, so that as the 

 surface of the ground is nearly level, each individual bed crops out at 

 the surface. One series of beds comprise layers of loosely compacted 

 calcareous sand ; others again are as hard as marble. The rocks are 

 very similar to those at Suva. At the Singatoka, however, there is no 

 trace of soapstone nearer than Thuvu, several miles away. There is no 

 non-porous capping to the Singatoka bedded limestones. 



The induration, therefore, of the raised reef limestones appears to have 

 been quite independent of the presence of an impervious overlying rock 

 such as "soapstone." 



In the Lau area, the metamorphism of soft coral into hard dense rock 

 is emphasized as strongly at the sea-level as on the island summits. The 

 recently elevated Vatu Leile reef-flat, the latter some 6 feet above high- 

 water mark, although strewn with hard corals, is hard and flinty as any 

 limestone observable anywhere. This statement must not be considered 

 to have universal application. This hardening extends only to the 

 greater part of the reef-flat, — that part composed only of reef-debris, — 

 and not the real coral masses representing a former belt or patch of 

 growing reef. The raised coral masses found in the lower cliffs of Mango, 

 Ngillangillah, Kambara, and Vatu Leile, although possessing an exceed- 

 ingly hard shell ringing and emitting sparks under the hammer, were 

 nevertheless soft and cellular within. So soft is the portion beneath this 

 hard exterior that individual corals may be crushed beneath the fingers. 

 At the same level, however, rock not formed of a coral mass is generally 

 solid throughout. 



This can be seen in a less degree on the " Liku " or cliff coast of the 

 Tongan Group. There whole cliffs of crumbling material, similar to those 

 observed at Singatoka (Plate 38), are exposed to the rollers of the Pa- 

 cific. All along the coast of Vavau great masses of rock are perpetually 

 falling and revealing a whole harvest of corals and shells more or less 

 indurated or changed to translucent calcite, and lying in a soft white 

 matrix. But where the cliff has preserved its integrity and still shows 

 the original slope of the reef seawards (Plate 36), there a hard crust of 

 limestone protects the soft interior. This is also observable on the fallen 

 masses, the resulting debris of the soft coral cliff. 



On the raised limestones of the Thuvu-Singatoka area a reef has 

 grown, which has since been elevated. While the greater part of this 

 reef mass is dense and hard as the Lau stone, the older basal rocks are 

 still soft as those of the Walu Bay area. 



