JALUIT, 283 



beach rock conglomerate cropping out on the lagoon side (PI. 162, figs. 1> 

 3, 4), and is the extension of tlie beds of beach rock conglomerate form- 

 ing the spurs we have described on the sea face of the shingle beach 

 (Pis. 164, 165). 



On the lagoon side of the beach rock conglomerate a narrow sink 

 has been formed between it and the numerous smaller shingle islets so 

 common in the lagoon of Jaluit (PI. 162, figs. 1, 3, 4), the outliers of a 

 former extensive coral conglomerate flat ; from the islets the slope is 

 gradual to the bottom of the lagoon itself. Immediately east of the 

 village of Jabor the island is widest, and the beach rock conglomerate 

 of the inner land face passes very gradually into the slope of the 

 lagoon (PI. 162, fig. 4), while further to the south, the belts of inner and 

 outer beach rock conglomerate are separated by a comparatively narrow 

 land rim (PI. 162, figs. 1, 3), showing that the inner and outer reef ledges 

 of beach rock conglomerate were once continuous, and as they were gradu- 

 ally elevated, have been eaten into on the one side to form the spurs on the 

 sea face (PI. 165), and on the other side to form the platform edging the 

 lagoon side of the reef flat (PI. 162, fig. 4). At some subsequent time, 

 the beach rock dam or coarse shingle beach was thrown up to its present 

 height ; the material for this dam was derived from the beach rock which 

 once filled the space between the spurs on the outer sea face, and whatever 

 material was planed off on the outer face from the top of the beach rock 

 platform. The beach rock conglomerate nowhere rises to more than about 

 two to three feet above high-water mark. 



The narrow parts of the outer land rim to the south of Jabor are bare ; 

 the blocks of beach rock conglomerate are not sufficiently disintegrated to 

 allow the growth of any vegetation ; but on some of the wider parts we 

 found Pisonias and Pandanus. The condition of the islands on the lagoon 

 side to the south of Kennedy's wharf gives an excellent idea of their mode 

 of formation, and how they have been thrown up on the lagoon side, and on 

 the wide lagoon reef flats of beach rock conglomerate. Secondary lagoons 

 have gradually been formed from the disintegration of the beach rock con- 

 glomerate by the waves of the lagoon ; the land rim has been gradually 

 widened on the lagoon side as on the outer face, but in a less degree. 



