2 FLORA OF ST. CROIX AND THE VIRGIN ISLANDS. 



l)ol(l iiiid rooky, f<>nniii<; abrupt promontories of considerable lieij^ht 

 and picturesque appearance, the hills and ridges on tlie other hand 

 being more rounded and of a softer outline. 



The Mliole group of islands, with the exception of Anegada, which is 

 built li}) of a tertiary limestone of very recent and probably pliocene 

 date, belongs to the cretaceous period,*showing as the principal rock a 

 breccia of felsite and scoriaceous stones, the cementing i)art of which 

 probably consists of decomposed hornblende, and having its cavities 

 commonly filled with quartz or calcareous spar. Besides this principal 

 rock, which is often found distinctly stratified, and which is called 

 Bluebit by the inhabitants, who generally employ the stone for 1)uilding 

 materials, limestone, diorite, clay-slate, and other less frequent minerals 

 also occur in the islands, forming, however, only a poor substratum for 

 vegetation everywhere. For the product of the decomposed rock is 

 generally a red heavy clay. Only Vieques shows a more fertile soil, pro- 

 duce«l by the alteration of a syenite-lilce diorite, its more level surface at 

 the same time allowing the fertile strata to remain on the surface; whilst 

 in the other islands the heavy rains as a rule will wash the loose cover- 

 ing of the ground down to the sea. 



From various facts observed in Anegada and A'irgin Gorda by Sir 11. 

 Schomburgk,+ as well as by Mr. Scott, in Vieques, at Porto Ferro Bay, 

 it appears tliat at the present jteriod the mIioIc chain of islands is slowly 

 rising, so that perhaps in a geologically siteaking not very distant time 

 most of the islands may become connected reciprocally and with Porto 

 Rico. 



To tlM' soutli oftlic ^'irgiIl Islands, at a distance of about .'Jl' miles, and 

 betwecMi 170 40' and ITo 47' X. hit., 04© 35' and 04^ 54' W. IcMig., lies the 

 island of St. Croix, geograi)hically considered an outlying i)art of the 

 former group, but separated from it by an immense chasm of more than 

 2000 fathoms, as statc<l above. This extraordinary ('rcvicehas no doubt 

 been formed at an early period, and ha*< in various respects contributed 

 materially to isolating the island from its neighbours. 



St. Croix is of about 57 s(iuarc miles, and has a triangular lonii. with the 



gicatesf leuglli, some L'O miles, from east 1o west, the greatest breadth 



being about 5 miles, iu the western ]tart of the island, which becomes 



gradually narrower towards the east. The coast-line is more <()nnected 



and the surlaee more le\4'l than in most of the Virgin Islands, tln' hills 



streieliiiig only along the !i(»itheni coast and tlirtiugh the eastern part of 



"Cii'vo: On tlu- (ieoioif.v of tin- North-fastcrn Wrst Intlin iHlniids. Stockholm, 1871, 

 tBorghuiis: Almauacb tiir tlas Jalir 1837, \>\k lO'i mul -40."*. 



