I9§ GEOLCfGY [Chap. IX 



Letter 535 Beagle in the S. Temperate regions, I concluded that shells, 

 the smaller corals, etc., etc., decayed and were dissolved 

 when not protected by the deposition of sediment ; and 

 sediment could not accumulate in the open ocean. Certainly 

 shells, etc., were in several cases completely rotten, and 

 crumbled into mud between my fingers ; but you will know 

 well whether this is in any degree common. I have expressly 

 said that a bank at the proper depth would give rise to an 

 atoll, which could not be distinguished from one formed 

 during subsidence. I can, however, hardly believe, in the 

 former presence of as many banks (there having been no 

 subsidence) as there are atolls in the great oceans, within a 

 reasonable depth, on which minute oceanic organisms could 

 have accumulated to the thickness of many hundred feet. 

 I think that it has been shown that the oscillations from 

 great waves extend down to a considerable depth, and if so 

 the oscillating water would tend to lift up (according to an 

 old doctrine propounded by Playfair) minute particles lying 

 at the bottom, and ;allow them to be slowly drifted away 

 from the submarine bank by the slightest current. Lastly, 

 I cannot understand Mr. Murray, who admits that small 

 calcareous organisms are dissolved by the carbonic acid in 

 the water at great depths, and that coral reefs, etc., etc., are 

 likewise dissolved near the surface, but that this does not 

 occur at intermediate depths, where he believes that the 

 minute oceanic calcareous organisms accumulate until the 

 bank reaches within the reef-building depth. But I suppose 

 that I must have misunderstood him. 



Pray forgive me for troubling you at such a length, but 

 it has occurred to me that you might be disposed to give, 

 after your wide experience, your judgment. If I am wrong, 

 the sooner I am knocked on the head and annihilated so 

 much the better. It still seems to me a marvellous thing 

 that there should not have been much and long-continued 

 subsidence in the beds of the great oceans. I wish that some 

 doubly rich millionaire would take it into his head to have 

 borings made in some of the Pacific and Indian atolls, and 

 bring home cores for slicing from a depth of 500 or 600 feet. 1 



1 In 1 891 a Committee of the British Association was formed for the 

 investigation of an atoll by means of boring. The Royal Society took 

 up the scheme, and an expedition was sent to Funafuti, with Prof. Sollas 



