406 FUNAFUTI: THE STORY OF A CORAL ATOLL. 



important, however, to observe that none of the borings yet made have 

 been sunk through the true growing substance of the atoll. They have 

 commenced on the lagoon side of the true coral reef, and the deeper 

 they have descended the more remote they have become from the ocean 

 flanks. The possibility exists, and should not be overlooked, that a 

 great part of the material passed through in the bore holes represents 

 dej)osits of the lagoon and of the fragmentary debris driven toward it 

 by the breakers. 



It will be observed that Professor David's bore hole does not trav- 

 erse the whole thickness of the table mountain; judging from the 

 soundings, it would have to descend 20 or 30 fathoms deeper to do this, 

 and it would seem likely that the material obtained from this last 20 

 or 30 fathoms might surpass in interest all the rest. Our friends in 

 Sydney fully appreciate this, and are so bent on probing this question 

 to the utmost that they have already dispatched, at great pecuniary 

 risk, an expedition to make a third attempt on Funafuti, and this time 

 to carry the bore hole right through the table mountain. 



The boring party is at this moment at work on the island, and before 

 many weeks have elapsed we may expect to receive tidings of their 

 success. A great stride will then have been taken toward a final 

 determination of the long-standing controversy on the origin of atolls. 1 



We eagerly await the result, which will inform us whether these 

 central oceanic islands are ancient remains of land which have plunged 

 beneath the sea and are renewing their youth, or whether they are 

 among the latest products of our planet, aspiring mountains which 

 have scarcely yet succeeded in their struggle upward to the light of 

 day; whether they are, as has been said, "a garland laid by the hand 

 of Nature on the tomb of a sunken island," or whether they may not be a 

 wreath of victory crowning a youthful summit on its first conquest of 

 the main. 



'The critical point has been passed. (See Nat. Sci. XIII, p. 362.) According to 

 the news from Funafuti (September 6) the boring attained a depth of 987 feet, or 

 147 feet below the base of the steepest cliff. The material passed tbrough was coral 

 limestone. It is of interest to observe that, soon after passing the bottom of Pro- 

 fessor David's bore hole, loose unconsolidated deposits ceased to be encountered, 

 and the drill passed with comparative facility through a hard limestone containing 

 numerous well-preserved corals. A crux of all theories of atolls is the lagoon. On 

 Darwin's theory its explanation follows naturally from the fundamental assump- 

 tion. Sir John Murray has to supplement his hypothesis by a separate explanation, 

 and proposes to account for the lagoon by solution. In this connection the success 

 which has attended an attempt of the present expedition to bore into the bed of the 

 lagoon is most welcome. The boring was made from the deck of H. M. S. Porpoise, 

 commanded by Captain StuWlee, and after passing through 101 feet of water sank 

 144 feet into the deposits of tbe floor. The first 80 feet were found to consist of the 

 calcareous alga Halimeda mixed with shells; the remaining 64 feet of the same 

 material, mingled with coral gravel. This alga is universally distributed over the 

 floor of the lagoon, as proved by an examination of the material obtained by Cap- 

 tain Field in sounding, and since it contains a certain percentage of magnesium 

 carbonate we are led to expect that the formation of dolomite will be found to stand 

 in some connection with the transformation of lagoon deposits. 



