chap. rv. 



Central Curved Ridge. 



93 



successive beds, of which this ridge is composed. On 

 the steep northern slope, I observed in several sections 

 a much worn undulating surface of red tuff, covered 

 by gray, decomposed, feldspathic lavas, with only a 

 thin earthy layer interposed between them. In an 

 adjoining part, I noticed a trap-dike, four feet wide, 

 cut off and covered up by the feldspathic lava, as is 

 represented in the woodcut. The ridge ends on the 



No. 10. 



Dike. 

 1 — G-ray feldspathic lava. 



2 — A layer, one inch in thickness, of a reddish earthy matter. 

 3— Brecciated, red, argillaceous tuff. 



eastern side in a hook, which is not represented clearly 

 enough in any map which I have seen ; towards the 

 western end, it gradually slopes down and divides into 

 several subordinate ridges. The best denned portion 

 between Diana's Peak and Nest Lodge, which supports 

 the highest pinnacles in the island varying from 2,000 

 to 2,700 feet, is rather less than three miles long in a 

 straight line. Throughout this space the ridge has 

 a uniform appearance and structure ; its curvature 

 resembles that of the coast-line of a great bay, being 

 made up of many smaller curves, all open to the south. 

 The northern and outer side is supported by narrow 

 ridges or buttresses, which slope down to the adjoining 

 country. The inside is much steeper, and is almost pre- 

 cipitous ; it is formed of the basset edges of the strata, 

 which gently decline outwards. Along some parts of 

 the inner side, a little way beneath the summit, a flat 

 ledge extends, which imitates in outline the smaller 

 curvatures of the crest. Ledges of this kind occur 



