92 St Helena. paet l 



side, where alone it is at all perfect, appears to vary 

 from a mile to a mile and a half. The basaltic strata, 

 as well as those of the subjacent basal series, dip, with 

 a moderate inclination, where they have not been sub- 

 sequently disturbed, towards the sea. The more broken 

 state of the basaltic ring round the eastern half, com- 

 pared with the western half of the island, is evidently 

 due to the much greater denuding power of the waves 

 on the eastern or windward side, as is shown by the 

 greater height of the cliffs on that side, than to leeward. 

 Whether the margin of basalt was breached, before or 

 after the eruption of the lavas of the upper series, is 

 doubtful ; but as separate portions of the basaltic ring 

 appear to have been tilted before that event, and from 

 other reasons, it is more probable, that some at least of 

 the breaches were first formed. Reconstructing in 

 imagination, as far as is possible, the ring of basalt, the 

 internal space or hollow, which has since been filled up 

 with the matter erupted from the great central crater, 

 appears to have been of an oval figure, eight or nine 

 miles in length by about four miles in breadth, and 

 with its axis directed in a NE. and SW. line, coincident 

 with the present longest axis of the island. 



The central curved ridge. — This ridge consists, as 

 before remarked, of gray feldspathic lavas, and of red,, 

 brecciated, argillaceous tuffs, like the beds of the upper 

 coloured series. The gray lavas contain numerous, 

 minute, black, easily fusible specks ; and but very few 

 large crystals of feldspar. They are generally much 

 softened; with the exception of this character, and of 

 being in many parts highly cellular, they are quite 

 similar to those great sheets of lava which overhang 

 the coast at Prosperous Bay. Considerable intervals 

 of time appear to have elapsed, judging from the 

 marks of denudation, between the formation of the 



