1835] FEATURES OF THE ARCHIPELAGO. 369 



height of between three and four thousand feet. Their 

 flanks are studded by innumerable smaller orifices. I 

 scarcely hesitate to affirm that there must be in the whole 

 archipelago at least two thousand craters. These consist 

 either of lava and scoriae, or of finely-stratified, sandstone- 

 like tuff. Most of the latter are beautifully symmetrical ; 

 they owe their origin to eruptions of volcanic mud without 

 any lava : it is a remarkable circumstance that every one of 

 the twenty-eight tuff-craters which were examined, had 

 their southern sides either much lower than the other sides, 

 or quite broken down and removed. As all these craters 

 apparently have been formed when standing in the sea, and 

 as the waves from the trade wind and the swell from the 

 open Pacific here unite their forces on the southern coasts 

 of all the islands, this singular uniformity in the broken 

 state of the craters, composed of the soft and yielding tuff, 

 is easily explained. 



Considering that these islands are placed directly under 

 the Equator, the climate is far from being excessively hot ; 

 this seems chiefly caused by the singularly low temperature 

 of the surrounding water, brought here by the great 

 southern Polar current. Excepting during one short season, 

 very little rain falls, and even then it is irregular ; but the 

 clouds generally hang low. Hence, whilst the lower parts 

 of the islands are very sterile, the upper parts, at a height 

 of a thousand feet and upwards, possess a damp climate 

 and a tolerably luxuriant vegetation. This is especially the 

 case on the windward sides of the islands, which first receive 

 and condense the moisture from the atmosphere. 



In the morning {i^th) we landed on Chatham Island, 

 which, like the others, rises with a tame and rounded 

 outline, broken here and there by scattered hillocks, the 

 remains of former craters. Nothing could be less inviting 

 than the first appearance. A broken field of black basaltic 

 lava, thrown into the most rugged waves, and crossed by 

 great fissures, is everywhere covered by stunted, sun-burnt 

 brushwood, which shows little signs of life. The dry and 

 parched surface, being heated by the noonday sun, gave to 

 the air a close and sultry feeling, like that from a stove : 

 we fancied even that the bushes smelt unpleasantly. 

 Although I diligently tried to collect as many plants as 

 [)ossible, I succ(U'ded in getting very few ; and such 

 wretched-looking little weeds would have bettor become 

 an arctic than an equatorial Flora. The brushwood 



