204 



PLUVIAMETEK — GEOLOGY. 



May 1829, 



observed, by which the error of the clock was satisfactorily 

 ascertained. 



Captain Foster's pluviameter, a cubic foot in size, placed on 

 a stand two feet above the ground, at an elevation of forty-five 

 feet above the sea, contained eight inches and a quarter of 

 rain, after standing thirty days ; therefore, with the quantity 

 evaporated, at least twelve inches must have fallen. The day 

 after the above was registered, the vessel only contained seven 

 inches and a quarter ; so that in twenty-four hours one inch 

 had evaporated, by which an idea may be formed of the sort of 

 weather we experienced, and of the humidity of the climate. 



With respect to the geological features, I can only add, that 

 all the islands on which I landed, and, I believe, all the others, 

 are composed of green-stone of various characters. The lower 

 portion, or base, being less decomposed, is a fine-grained green- 

 coloured rock, in which the component parts are so blended as 

 not to be distinguished from each other. It appears sometimes 

 in strata, dipping at various angles, from 20° to 45° from the 

 vertical ; and is very similar to the rock which alternates with 

 granite in the Straits of Magalhaens, at the entrance of the 

 Barbara ; and also to that about Pond Harbour, and Bell Bay, 

 At a greater elevation the feldspar predominates, the hornblende 

 is observed in distinct crystals,"^" and the rock contains a con- 

 siderable quantity of iron, which is observed in the reddish 

 tinge of its surface. I have before noticed the magnetic property 

 of this rock, which was more or less according to the quantity 

 of hornblende : the beach-stones are different sorts of green- 

 stone. 



The lower parts of the hills, around St. Martin'*s Cove, are 

 thickly wooded with the smooth-leaved, evergreen beech, which 

 I have before described. Its leaves were as fresh and vivid, 

 when we sailed, as if it were the height of summer ; but those 

 of the deciduous-leaved beech had assumed their autumnal tint, 

 and were falling fast. Neither species attained a greater size, 

 in diameter, than six or eight inches. The Winter's-bark was 



* This rock is very similar to the boulders and pebbles which we found 

 on the beach at Point St. Mary (Freshwater Bay). 



