chap. iv. Flagstaff Hill and the Bam. 89 



been denuded, it was probably higher than this ridge, 

 from which it is separated by a broad and much lower 

 tract of country; we here, therefore, see that the lower 

 extremity of a set of lava-streams have been tilted up 

 to as great a height as, or perhaps greater height than, 

 the crater, down the flanks of which they originally 

 flowed. I believe that dislocations on so grand a scale 

 are extremely rare l in volcanic districts. The forma- 

 tion of such numbers of dikes in this part of the island 

 shows that the surface must here have been stretched to a 

 quite extraordinary degree : this stretching, on the ridga 

 between Flagstaff and Barn Hills, probably took place 

 subsequently (though perhaps immediately so) to the 

 strata being tilted ; for had the strata at that time 

 extended horizontally, they would in all probability 

 have been fissured and injected transversely, instead of 

 in the planes of their stratification. Although the 

 space between the Barn and Flagstaff Hill presents a 

 distinct anticlinal line extending north and south, and 

 though most of the dikes range with much regularity 

 in the same line, nevertheless, at only a mile due south 

 of the ridge the strata lie undisturbed. Hence the 

 disturbing force seems to have acted under a point, 

 rather than along a line. The manner in which it has 

 acted, is probably explained by the structure of Little 

 Stony-top, a mountain 2,000 feet high, situated a few 

 miles southward of the Barn ; we there see, even from 

 a distance, a dark-coloured, sharp, wedge of compact 

 columnar rock, with the bright-coloured feldspathic 

 strata, sloping away on each side from its uncovered 

 apex. This wedge, from which it derives its name of 

 Stony-top, consists of a body of rock, which has been 



1 M. Constant Prevost ('Mem. de la Soc. Gcolog.' torn, ii.) 

 observes, that ' les produits volcaniques n'ont que localement et 

 rarement meme derange le sol, a travers lequel ils se sont fait jour.* 



