106 SL Helena. part i. 



the parts which I was able to examine) by a ring of 

 basaltic mountains, now much broken, but evidently 

 once continuous. These mountains have, or apparently 

 once had, their escarpements steep towards the interior 

 of the island, and their strata dip outwards. I Vas 

 able to ascertain, only in a few cases, the inclination of 

 the beds ; nor was this easy, for the stratification was 

 generally obscure, except when viewed from a distance. 

 I feel, however, little doubt that, according to the re- 

 searches of M. Elie de Beaumont, their average in- 

 clination is greater than that which they could have 

 acquired, considering their thickness and compactness, 

 by flowing down a sloping surface. At St. Helena, 

 and at St. Jago. the basaltic strata rest on older and 

 probably submarine beds of different composition. At 

 all three islands, deluges of more recent lavas have 

 flowed from the centre of the island, towards and be- 

 tween the basaltic mountains ; and at St. Helena the 

 central platform has been filled up by them. All 

 three islands have been raised in mass. At Mauritius 

 the sea, within a late geological period, must have 

 reached to the foot of the basaltic mountains, as it now 

 does at St. Helena ; and at St. Jago it is cutting back 

 the intermediate plain towards them. In these three 

 islands, but especially at St. Jago and at Mauritius, 

 when, standing on the summit of one of the old basaltic 

 mountains, one looks in vain towards the centre of the 

 island. — the point towards which the strata beneath 

 one's feet, and of the mountains on each side, rudely 

 converge, — for a source whence these strata could have 

 fceen erupted ; but one sees only a vast hollow platform 

 stretched beneath, or piles of matter of more recent 

 origin. 



These basaltic mountains come, I presume, into 

 the class of Craters of elevation : it is immaterial 



