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Sect, v.] 



GEOGRAPHY 



141 



ancliorage ? Are there aiiv harbours along the coast ? 

 and liow far have natural harbours been rendered more 

 available and safe by the erection of breakwaters or 



piers ? 



In concluding this portion of the first division of phy- 

 sical geography, I would also mention a few points con- 

 nected with the physical ff:^atures of the country which 

 deserve notice, but which, being of an aceidenta 

 than of a normal character, did not easily find a place in any 

 of the natural subdivisions of the subject. The traveller 

 should always pay particular attention to those pheno- 



t" 



raena in the physical structure of the country which may 

 be called by some persons natural curiosities. 



Amongst 



the principal of these are grottoes, caves, and caverns ; 

 some of them are not only strikingly beautiful, but of 

 great scientific interest. They are more usually met 

 witli in limestone districts than in any other ; it is interest- 

 ing to ascertain their size and extent, and tlie distance to 

 which they have been traced. Are they traversed by 

 subterranean streams, and if so, do these streams enter 

 or escape by known channels or mouths, as is frequently 

 the case in Istria and Carniola, and in the west of Ire- 

 land? Natural bridges present another instance of this 

 khid of phenomena. IIow have they been formed^ and 

 what is the nature of the rock of which they consist? 

 Are they stalactitic, or of a more compact nature ? Mines 

 are also to he noticed, although they come more directly 

 under the head of geological observation. All volcanic 

 phenomena and earthquakes are also deservdng of notice. 



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usual occurrence ; and any information respecting them 



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