CORAL REEFS 285 



are in the track of great oceanic currents, as the San 

 Pedro, Yucatan and Florida and Bahama Banks, do yet 

 form an important bulk in the mass of the debris added 

 to the original bank, the level of which was due to the 

 folding of the crust in much earlier periods, at a time 

 when the principal orographic features were laid down. 

 My experience has been that shells, etc., in these pla- 

 teaus wbich are in the track of currents, are fairly well 

 preserved after death, although covered with mud (made 

 up mainly of the coral ooze and of Globigerina ooze) 

 which cemented them to the older layer of dead shells, 

 etc., below, and formed the base upon which the present 

 living forms were thriving. Your objection that there 

 is not great probability of finding in the Pacific as many 

 banks as there are atolls is certainly a very strong one 

 and one which seems to me can only be met by showing in 

 subsequent surveys that these atolls are themselves only 

 slightly raised patches upon large banks, the orography 

 of which we do not as yet know. This is a problem in 

 hydrography of the Pacific which I have had in view for 

 a long time and hope to solve one of these days. 



With reference to the chemistry of the reefs and the 

 action of all this large amount of carbonate of lime held 

 in suspense in the water, I must acknowledge I know 

 nothing, and I do not see the why of the action of car- 

 bonic acid as a solvent at one depth and not at another 

 — if not in exact proportions to the pressure. This part 

 of Murray's argument seems to me untenable, if I un- 

 derstand him correctly, and we seem to have viewed his 

 explanation alike. There is constant talk of making bor- 

 ings at St. Augustine for sinking artesian wells, and 

 whenever they start I shall be sure to keep close watch 

 of their proceedings, which ought to settle a good 



