8 



ST. PAULAS ROCKS. 



Feb. 1832. 



during the morning of February 16th^ close to the island of 

 St. Paul. This cluster of rocks is situated in 0° 58' north 

 latitude^ and 29° 15' west longitude. It is 540 miles distant 

 from the coast of America^ and 350 from the island of Fer- 

 nando Noronha. The highest point is only fifty feet above the 

 level of the sea^ and the entire circumference is under three- 

 quarters of a mile. This small point rises abruptly out of 

 the depths of the ocean. Its mineralogical constitution is 

 not simple ; in some parts^ the rock is of a cherty, in others^ 

 of a felspathic nature ; and in the latter case it contains thin 

 veins of serpentine,, mingled with calcareous matter. 



The circumstance of these rocks not being of volcanic 

 origin is of interest^ because^ with very few exceptions^ the 

 islands situated in the midst of the great oceans are thus 

 constituted. As the highest pinnacles of the great moun- 

 tain ranges probably once existed as islands distant from any 

 continent, we are led to expect that they would frequently 

 consist of volcanic rocks. It becomes, therefore, a curious 

 point to speculate on the changes which many of the present 

 islands would undergo, during the lapse of the countless 

 ages, which would be required to elevate them into snow- 

 clad summits. If we take the case of Ascension, or St. 

 Helena, both of which have long existed in an extinct con- 

 dition, we may feel assured, before so vast a period could 

 elapse, during the whole of which the surface would be ex- 

 posed to constant wear and tear, that the mere nucleus or 

 core of the island would remain ; perhaps, every fragment of 

 cellular rock having been decomposed, a mass of some com- 

 pact stone, as phonolite or greenstone, would crown our new 

 Chimborazo. 



The rocks of St. Paul appear from a distance of a bril- 

 liantly white colour. This is partly owing to the dung of a 

 vast multitude of seafowl, and partly to a coating of a glossy 

 white substance, which is intimately united to the surface of 

 the rocks. This, when examined with a lens, is found to 

 consist of numerous exceedingly thin layers, its total thick- 

 ness being about the tenth of an inch. The surface is smooth 



