

22 



REMARKS 



O N 



THE 



STRATA, of the fame nature with the former ifles. Tanna has on its fhores 



coral rocks and madrepores : the beaches are covered with a blackifli 

 iand, confuting of minute pieces of flierl and pumice-ftone, which arc 

 formed by the aihes conftantly thrown up by a volcano, and fcattered 

 over the whole furface of the iiland. [Pu?nex cinerarius, Linn.) llie 



^ 



furface of the whole ifle confiils therefore of this pumice-fand 



mixed with a black mould formed 



the putrified vegetables. 



The pumice-fand 



y abundant ; for there is at certain times 



feveral leagues diftant from the volcano 



leaf of any 



or 





plant, nor any grafs, which is not entirely covered wdth afhes, 



■ 



which lexairaned, and found to be this very pumice-fand : however, 

 this forms a mofl admirable afhy, fertile foil, in which all vegetables 

 thrive with the greateft luxuriance. We found a few lingle de- 

 tached rock-ftones -, being a mixture of quartz and black daze or 



r 



mica -y nay, one of thefe pieces was a coarfe dilTolved granite, co- 

 vered with black button-ore, which is a fort of iron-ore. 



The chief flrata of the ifle, as far as I could form a judgment of 

 them, from the various cliffs furrounding the harbour, are of a clay 

 mixed with aluminous earth, interfperfed with lumps of pure chalk. 

 The ilrata of the clay are about fix inches more or lefs, deviating 

 very little from the horizontal line. In a few places I found a foft, 

 blackifh fand-flone, compofed of the aflies fpread by the volcano, 

 and fome parts of clay. Kere and there I obferved a fubftance com- 



mon ly 



