CHAP, XIY.] 



ST. HELENA. 



283 



northern rim forms the highest and central ridge of the island. 

 Many other hills and peaks, however, are more than two thousarid 

 feet high, and a consider?J)le portion of the surface consists of a 

 rugged plateau, having an elevation of about fifteen hundred to 

 two thousand feet. Everything indicates that St. Helena is an 

 isolated volcanic mass built up from the depths of the ocean. 

 Mr. Woliaston remarks : There are the strongest reasons for 

 believing that the area of St. Helena was never very much larger 

 than it is at present — the comparatively shgillow sea-soundings 

 within about a mile and a half from the shore revealing an 

 abruptly defined ledge, hcyond which no bottom is reached at a 

 depth of 250 fathoms ; so that the original basaltic mass, which 

 v/as gradually piled up by means of successive eruptions from 

 beneath the ocean, would j^ppear to have its limit definitely 

 marked out by this suddenly-terminating submarine cliff — the 

 space between it and the existing coast-line being reasonably 

 referred to that slow process of disintegration by which the 

 island has been reduced, through the eroding action of the 

 elements, to its present dimensions." If we add to this that 

 between the island and the coast of Africa, in a south-easterly 

 direction, is a profound oceanic gulf known to reach a depth of 

 2,860 fathoms, or 17,160 feet, while an equally deep, or perhaps 

 deeper, ocean, extends to the west and south-west, we shall be 

 satisfied that St. Helena is a true oceanic island, and that it 

 owes none of its peculiarities to a former union with any 

 continent or other distant land. 



Change effected hy European occupation. — Vv^hen first dis- 

 covered, 378 years ago, St. Helena was densely covered with a 

 luxuriant forest vegetation, the trees overhanging the seaward 

 precipices and covering every part of the surface with an ever- 

 green mantle. This indigenous vegetation has been almost 

 wholly destroyed ; and although an immense number of foreign 

 plants have been introduced, and have more or less completely 

 established themselves, yet the general aspect of the island is 

 now so barren and forbidding that some persons find it difficult 

 to believe that it was once all green and fertile. The cause of 

 the change is, however, very easily explained. The rich soil 

 formed by decomposed volcanic rock and vegetable deposits 



