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Sect VI.] 



GEOLOGY. 



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marks, or beds of coarse pebbles, or otber indications of 

 the strata having been deposited iu shallow water ? What 

 is the tliickness, form, and dimensions of the beds of salt ? 



H-iimens of the salt, and of any associated saline sub- 

 stances, ought to be brought home in bottles for analysis. 

 The oriffin of beds of salt, found in formations of very 

 different ages in different parts of the world, is at present 

 quite obscure ; some authors attribute it to the sinking of 

 superficial sea-water, rendered more saline by evaporation , 

 others to the evaporation of sea- water periodically over- 

 flowing extensive low sandy tracts, like parts of the Run 



of Cutch ; others suspect that its deposition is in some 

 unknown way connected with the sea's bottom having 

 been heated by volcanic action. In some countries there 

 are large lakes of brine, often covering thick beds of salt ; 

 these deserve examination: on what does such salt or 

 brine rest, whether on the bared underlying strata, or on 

 «and or gravel, such as cover the surrounding country ? 

 Does the salt contain the remains of animals or plants ? 

 Specimens of the salt ought to be brought 

 bottles, and attention paid, whether beneath it there is 

 any thin layer of other saline substances. 



aeava(/e.--T\ie slaty structure of rocks will at first 

 perplex the young geologist ; for in proportion as it be 



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comes well developed, the planes of stratification or of 

 original deposition become obscnre, and are often quite 

 obliterated. As the sea-voyager, and especially the sur- 

 veyor, often visits numerous points on the same line of 

 coast, he possesses some great advantages for studying 

 this subject, and numerous observations made with care 



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