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191 



GEOLOGY. 



[Sect. VI. 



Fringing reefs on the other, depend on the effect produced 

 on the upwardly-growing corals hy the slow sinking or 



rising of their foundations. 



A thick and widely-extended mass of upraised recent 

 coral-rock has never yet been accurately examined, and 

 a careful description of such a mass— especially if the 

 area included a central depression, showing that it origi- 

 nallv existed as an atoll— is a great desideratum. Of 

 what nature is the coral-rock ; is it regularly stratified or 

 crossed by oblique layers ; does it consist of consolidated 

 fine detritus or of coarse fragments, or is it formed of 



upright corals embedded as they grew ? Are many shells 

 or the bones of fish and turtle included in the mass, and 

 are the boring kinds still in their proper positions ? The 

 thickness of the entire mass and of the principal strata 

 should be measured, and a large suite of specimens col- 

 lected. 



In conclusion, it may be re-urged that the young geo- 

 logist must bear in mind, that to collect specimens is the 

 least part of his labour. If he collect fossils, he cannot 

 go wi^ong ; if he be so fortunate as to find the bones ol 

 any of the higher animals, he will, in all probability, make 

 imnortant discovery. Let him, however, remember 



an "! 



that he will add 



reatly to the value of his fossils 



that he will aaa greaiiy lo uk vaiuc ux ...^ ^— ^ j 



iabellinff every single specimen, by never mingling those 



n-om two formations, and by describing tlie succession of 

 the strata whence they are disinterred. But let his aim 

 be higher : by making sectional diagrams as accurately as 

 possible of every district which he visits (nor let him sup- 

 pose that accuracy is a quality to be acquired at willj, by 



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