104 St. Helena. past i. 



2,000 feet high, presents, according to Mr. Seale, a 

 perfect network of truncated dikes : on hills like the 

 Flagstaff, formed of soft rock, we might suppose that 

 the dikes had been worn down and cut off bv meteoric 

 agency, but we can hardly suppose this possible with 

 the hard, basaltic strata of the Barn. 



Coast denudation. — The enormous cliffs, in manv 

 parts between 1.000 and 2.000 feet in height, with 

 which this prison-like island is surrounded, with the 

 exception of only a few places, where narrow valleys 

 descend to the coast, is the most striking feature in its 

 scenery. We have seen that portions of the basaltic 

 ring, two or three miles in length by one or two miles 

 in breadth, and from one to two thousand feet in height, 

 have been wholly removed. There are, also, ledges and 

 banks of rock, rising out of profoundly deep water, and 

 distant from the present coast between three and four 

 miles, which, according to Mr. Seale, can be traced to 

 the shore, and are found to be the continuations of 

 certain well-known great dikes. The swell of the 

 Atlantic Ocean has obviously been the active power in 

 forming these cliffs ; and it is interesting to observe 

 that the lesser, though still great, height of the cliffs 

 on the leeward and partially protected side of the 

 island, (extending from the Sugar-Loaf Hill to South 

 West Point.) corresponds with the lesser degree of 

 exposure. When reflecting on the comparatively low 

 coasts of many volcanic islands, which also stand ex- 

 posed in the open ocean, and are apparently of consider- 

 able antiquity, the mind recoils from an attempt to 

 grasp the number of centuries of exposure, necessaiy to 

 have ground into mud and to have dispersed the enor- 

 mous cubic mass of hard rock which has been pared off 

 the circumference of this island. The contrast in the 

 superficial state of St. Helena, compared with the 



