512 Prof. W. J. Sollas. Report to Coral Reef Committee. 



tion, as is the coral platform which, extends from 

 them, up to and under the hurricane beach. This 

 breccia was probably formed and cemented toge- 

 ther when the reef stood at least 4 feet lower than 

 at present, and was produced by the breakers 

 driving fragments of corals from the seaward edge 

 of the reef into the lagoon, as they are now doing 

 over the isthmuses, submerged at high tide, which 

 connect the several islets of the atoll together. 



If it should prove true, as I do not doubt, that 

 one of the latest episodes in the history of the reef 

 has been an elevation of, say, 4 feet, then in the 

 immediately antecedent stage, the reef must have 

 been awash, or, perhaps, wholly submerged, and 

 the present terrestrial fauna and flora must have 

 reached it subsequent to its elevation, as sea drift, 

 or have been introduced by human agency. 



In conclusion, I would add that to myself the 

 soundings obtained by Captain Field appear to 

 support Darwin's theory of coral atolls ; there 

 remains, however, one very important branch of 

 the subject which stands in need of renewed in- 

 vestigation, and this is the bathymetiical limit to 

 coral life. 



Not till I had obtained a close acquaintance with 

 the difficulties of dredging on the steep sides of an 

 atoll did I recognise on how frail a basis our 

 accepted conclusions rest. It is a task difficult 

 enough to get up corals from the lagoon in com- 

 paratively shallow water ; from the sides of the 

 reef it is well nigh impossible. To obtain dead 

 corals from great depths proves little ; living corals 

 are generally found with dead associates, and the 

 latter are the more readily detached and brought 

 to the surface. * 



The weight of the evidence we already possess 

 is admittedly in favour of a comparatively shallow 

 bathy metrical limit, but much remains to be done 

 before we can speak of any limit as definitely 

 ascertained. 



