134 OBSERVATIONS ON THE GEOLOGY OF THE 



From the decomposing nature of the surface, it would be no easy 

 task to arrive at a speedy conclusion respecting its whole structure. It 

 appeared to me to rest on a granitic base, covered by various admixtures. 

 The superincumbent mass is heterogenous. Lime stone in various stages ; 

 veins of quartz and ores of iron are most prominent ; calcareous incrusta- 

 tions line the hollows of the cliffs ; where also the agaric mineral abounds; 

 — and the cliffs are, in some places, curiously marked by broad vertical 

 ribbon-like streaks, varying in colour according to the strata from which 

 the water, containing the colouring matter, has flowed — white, black, and 

 dark bluish, and slate colours, are most frequent. At the south end 

 about half way up the cliff", there are magnificent natural arches. The 

 grotesque calcareous stalactites, which depend just over the entrances to 

 these, give them, as a whole, the aspect of a decayed gothic ruin. 



A cavern has been formed quite through the north end of the rock by 

 the action of the sea below, and the gradual decay of the structure above. 

 Stalactites here abound. 



Our boat carried us into the centre of this cave; it is gloomy, but the 

 roof is perhaps fifty feet high, and dome-shaped though rugged. Here 

 were observed flimsy ladders of flexible cane, stretched betwixt projec- 

 tions of the rock, and on emerging from the cavern, similar ladders were 

 observed to have been arranged up the face of the cliff, in a zig-zag man- 

 ner, here fastened to a jutting point of rock — ^there reeved through a 

 perforated angle. These had been thus placed by adventurous Malays, 

 in quest of the edible birds' nests. Their trade is more dangerous than 

 that of the samphire gatherer, or the Hebridian Birder ; but it is more 

 profitable than either. Several of the birds' nest islands, in this line, 

 have been so tortuously hollowed out by the slow operation of ages, that, 

 previous to going in, the nester fastens to the entrance the end of the clew 



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