86 A NATURALIST ON DESERT ISLANDS. 



a few feet above sea-level, the dry clay-like homogeneous 

 deposit under disciission. 



How deep the deposit extends it is of course impossible 

 to state ; but in sinking the foundations for a w ireless 

 telegraph installation, it was found to extend for at least 

 twenty feet, and it may, of course, continue for a hundred 

 or even far more. 



The " laird " was considerably interested in this deposit ; 

 and was hoping to turn it to good account by shipping 

 it to the States, where it might be used for the same 

 purposes as fuller's earth, and so add very greatly to the 

 value of his island. For our part, however, we were far 

 more interested in the history of its origin and the light 

 it might possibly shed upon the changes of level which 

 had taken place in past geological ages in this part of the 

 Caribbean Sea. 



Our first thought, on viewing these deposits, was that 

 here in this little island in the \^ estern Caribbean, we might 

 have, on a small scale, a replica of the conditions which 

 once obtained in the island of Barbados, when that island 

 first thrust its head above sea-level after rising from the 

 abysmal depths to which at one period it had been plunged. 

 Curiousl}^ enough, we had visited Barbardos six weeks 

 or so before our arrival at Swan Island ; and after reading 

 Mr. Jukes Brown's interesting account of the geology 

 of that island, had made a small expedition to the hilly 

 " Scotland " district. Here we had seen, on Bissex Hill, 

 those calcareous and siliceous earthy deposits — ^full of 

 the dead skeletons of minute oceanic creatures, known as 

 Foraminifera and Eadiolaria, which prove, as fully as 

 anything can be proved, that Barbados at one period 

 of its formation was plunged (after its foundations had 

 been laid down in shallow water adjacent to some high, 

 mountainous land) to a depth of something between 

 12,000 to 18,000 feet or more beneath the sea. Now, as 

 Mr. Jukes Brown states, " Radiolarian ooze does not 

 exist in the Atlantic, but is found in the Pacific and Indian 

 Oceans at depths of from 2,000 to 4,000 fathoms. Its 



