110 A NATURALIST ON THE " CHALLENGER." 



usually narrow, and is not unlike that exposed in the Grand Cural 

 at Madeira in appearance. 



Streams, or rather cascades, which come dashing down to the 

 sea during the constant heavy rains, have eaten their way into 

 the cliffs, and their beds form conspicuous features in the view as 

 narrow gullies, descending the rocks in a series of irregular steps. 

 At the foot of the cliffs, immediately opposite the anchorage, are 

 debris slopes and irregular rocky and sandy ground, forming a 

 narrow strip of low shore land. 



The settlement lies on a broader and more even stretch of 

 low land which extends westwards. In the margin of this 

 lower tract a small low secondary cliff has been formed by the 

 waves. Steep debris slopes lead from the cliffs above to the 

 settlement tract, and the cliffs are here and there broken into 

 ledges and deep gullies, by which ascent to the summit is easy. 



At the landing-place the beach is formed of black volcanic 

 sand, but elsewhere in the neighbourhood, of coarse basaltic 

 boulders. At the summit of the Peak, as the inhabitants told 

 us, is a crater basin with a lake at the bottom of it. From their 

 description given, it appears that there is something like the 

 Canadas of the Peak of Teneriffe, around the terminal crater. 



The cliffs have a scanty covering of green, derived mainly 

 from grasses, sedges, mosses, and ferns, with darker patches of 

 the peculiar trees of the island (Phylica arhoi m), and the crowberry 

 (Empetrum nigrum var. rubrum). These dark patches become 

 more and more marked towards the summit. Conspicuous 

 patches of bright green are formed under the cliffs at the foot of 

 the watercourses by a dock (Rumex). Further dotted about 

 amongst the other herbage are rounded tufts of pale blueish- 

 green, consisting of the tall reed-like grass (JSpartina arun- 

 dinacea), which is peculiar to the Tristan da Cunha group and 

 Amsterdam Island. 



On nearer inspection the damp foot of the cliff is found to 

 be covered with mosses and liverworts, which latter form, in 

 favourable situations, continuous green sheets covering the earth 

 beneath the grass. 



Two ferns, an Asplenium (A. obtusatum, Forst.), growing in 

 the clefts of the rocks just as does our home A. marimcm, and 



