70 



FOYE. 



basin-shaped and marked by numerous pits and caves similar to those 

 of Kambara. The island has another feature not seen at Kambara, 

 a central lake, three quarters of a mile across. The tide rises and 

 falls in the lake about which toadstool islets of limestone stand and 

 steep cliffs 75 to 100 feet in height rise about its edge. The depth 

 of the lake varies. Near its shore and for some distance out it 

 is only 4 to 5 feet deep and its bottom is covered with a black vege- 

 table mold. In places, however, the bottom cannot be seen. From 

 statements made by the natives the average depth near its center 

 appears to be 3 to 4 fathoms. 



There are many underground caverns about the edge of the lake and 

 certain of these undoubtedly connect it with the sea. At one point 

 on the northern side, there is a depression in the rim of the island and 

 the limestone beneath is shattered, though there is no wide opening. 

 The depression is probably due to the collapse of a cavern roof. 



Figure 33. Profile of Wangava as seen from Kambara. 



The bmestones collected show that re-crystallization has gone on ex- 

 tensively near the center of the island and to a smaller degree near its 

 edge. Sideritic veins and pockets abound. The limestone is com- 

 posed mostly of coral rubl)le and shell waste. In fact no good exam- 

 ples of coral heads in place were seen, even in the rim of the islantl. 



As already noted, the northwestern shore of Wangava has a fault- 

 scarp parallel to the one described in Kambara. There are depths 

 of 100 fathoms close to the shore; no reef exists on this side of the 

 island and the coast-line is very regular. It is inferred that the fault 

 which affected Kambara, affected Wangava also. 



The narrowness of the fringing reef about the other sides of the 

 island suggests, as at Kambara, the recency of the. establishment of 

 the present shore-line, presumably by uplift. If a platform had l)een 

 cut during the IMeistocene period, the recency of the uplift would 

 imply that this bench should now be above sea-level since the island 

 has l)een uplifted 350 to 400 feet, an amount greater than the sup- 

 posed rise of the ocean due to the return of Glacial waters. The upper 



