88 St. Helena, paet u 



states, that one near the Barn, in a height of 1,260 feet, 

 decreases in width only four inches, — from nine feet at 

 the bottom, to eight feet and eight inches, at the top. 

 On the ridge, the dikes appear to have been guided in 

 their course, to a considerable degree, by the alterna- 

 ting: soft and hard strata : they are often firmly united 

 to the harder strata, and they preserve their paral- 

 lelism for such great lengths, that in very many in- 

 stances it was impossible to conjecture, which of the 

 beds were dikes, and which streams of lava. The dikes, 

 though so numerous on this ridge, are even more 

 numerous in the valleys a little south of it, and to a 

 degree I never saw equalled anywhere else : in these 

 valleys they extend in less regular lines, covering the 

 ground with a network, like a spider's web, and with 

 some parts of the surface even appearing to consist 

 wholly of dikes, interlaced by other dikes. 



From the complexity produced by the dikes, from 

 the high inclination and anticlinal dip of the strata of 

 the basal series, which are overlaid, at the opposite 

 ends of the short ridge, by two great masses of different 

 ages and of different composition, I am not surprised 

 that this singular section has been misunderstood. It 

 has even been supposed to form part of a crater ; but 

 so far is this from having been the case, that the summit 

 of Flagstaff Hill once formed the lower extremity of a 

 sheet of lava and ashes, which were erupted from the 

 central, crateriform ridge. Judging from the slope of 

 the contemporaneous streams in an adjoining and un- 

 disturbed part of the island, the strata of the Flagstaff 

 Hill must have been upturned at least twelve hundred 

 feet, and probably much more, for the great truncated 

 dikes on its summit show that it has been largely 

 denuded. The summit of this hill now nearly equals 

 in height the crateriform ridge; and before having 



