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must have occurred in the levels of the isUiids to aj^ 

 mit of the formations which Av.e find on them. The 

 mere fact of the existence of a fossil forest on the shores 

 of Gabriel island is an indubitable proof of a rise, a 

 subsequent depression below, sea-level, and finally a, 

 second rise above it must have occurred ; for it is as 

 impossible that a fossilisation or replacement of woody, 

 by calcareous matter could occur in the atmosphere, as 

 that trees should grow in the sea. The total absence 

 ojF sea-shells or corals in this stratum affords further 

 evidence that, the forest could not have been washed 

 by the sea when even lashed to its greatest fury by the. 

 •winds. 



We have further evidence that both ^lat and Ga- 

 briel islands have been submerged to a corjsiderable 

 depth since we find coral blocks on the hill of the fonur- 

 er island at a height of thirty to forty feet i and on Ga- 

 briel, large masses of the forest-form^tipn have been, 

 raised to 80 feet above the present level of the sur- 

 rounding sea. 



The rapid destruction of the tree-formation on the 

 eastern shore of Gabriel, now going on together with, 

 the extensive traces of the same for.niation around its 

 shores, as well as on one single point of, Flat island 

 afford sufficient evidence of the existence of a large 

 track of land at some former geological period, and 

 that a recent one because, so far as I have been able to. 

 ascertain, the fossil sea-shells and corals in the stra- 

 tum beneath the free-formati.on, still exist in a living, 

 slate in the surrounding sea. 



That at sonje former period thpse islands together, 

 "with Gunners' Quoin, Round and Serpent islands were 

 connected with Mauritius as one island is probable ;. 

 but that Gunners' Quoin, Flat and Gabriel, islands 

 were so connected is rendered almost certain by the 

 fact that Helix rufa, is found fossil among the roots of 

 the fossil trees on Gabriel while the sam.e species still 

 exists in a living state in Mauritius. Nor Avould any 

 very great alteration in level be re(i.uired to connect 

 Mauritius with the three islands just mentioned, as the, 

 greatest depth of sea in the channel between these is- 

 lands scarcely exceeds 00 fathoms or 3(?0 feet ; and f; 



