1871.] 



RATTEA.T FERNAirDO NOEONHA. 



33 



5; 2' 





s 



5- 



?i 



^ 



bp 



N.E. of Cape San Eoqiie, the most eastern part of the South-Ame- 

 rican continent, the intervening channel being comparatively shaUow 

 compared with the deeper 

 waters to the east and north- 

 east. The geology and physical 

 geography of the two, thus con- 

 tiguous, ought evidently there- 

 fore to be studied together. 

 And it would be interesting to 

 know whether these islands, a 

 mere speck in the ocean and 

 their rock-formations, are or 

 are not connected with the 

 enormous mountain-chains and 

 rock-systems of the adjacent 

 mainland — the volcanic rocks 

 of the former with the igneous 

 mass which forms so large a 

 part of Central, Southern, and 

 Eastern Brazil, and especially 

 with the mo an tain -chains run- 

 ning for hundreds of miles 

 along this coast in a N.E. direc- 

 tion to terminate near 'Cape San 

 Roque, of which Fernando 

 Noronha may be regarded as a 

 terminal spur. May not the 

 conglomerate of Fernando No- 

 ronha be likewise connected in 

 origin and nature vsdth the 

 weU-marked tertiary deposits 

 flanking these mountain-chains 

 of Eastern Brazil ? 



Evidence of a gradual ver- 

 tical movement in these islands 

 in comparatively recent times 

 is not wanting, thus : — -Jirst, 

 in the old high-water mark of 

 the group being considerably 

 above its present level, as seen, 

 for example, at the base of the 

 Fort Eoek, Le Grange, Les 

 Jumeaux, &c. ; and, second, in 

 the sides of Booby Island, now 

 hollowed into a long series 

 of caves, whose roofs lie well 

 overhead. The nature of a 

 large perforation in the inner 

 end of Cape Placelliere, appa- 

 rently in basalt, and high above 



VOL. XXVril. PAKT I. 



