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442 



ILLUSTRATIONS OF THE 



within a period comparative!^ of no great ex- 

 tent. 



It will be ealily underftood, that the fads we 

 are going to ftate, each taken lingly, prove no- 

 thing more than a change of the line in which 

 the furface of the fea interfedls the furface of 

 the land, leaving it uncertain to which of the 

 two the change ought really to be afcribed. Ta- 

 ken in combination, however, thefe fa6ls may 

 determine what each of them feparately cannot 

 afcertain. I fhall firil, therefore, mention fome 

 of the principal obfervations 



change above mentioned, an 



s relative to the 

 d fhall then com- 

 pare them, in order to difcover whether it is mofl 

 probable that this change has been produced by 



of the 



a 



d or of the fea 



388. If we begin with examining the coafls of 

 our own ifland, we fliall find clear evidence every 

 where, that the fea once reached higher up up- 

 on the land than it does at prefent. The marks 



of an ancient fea-beach are to be feen beyond the 

 prefent limits of the tide, and beds of fea-fhells', 

 not mineralized, are found in the loofe earth or 



J 



foil, fometimes as high as thirty feet above the 

 prefent level of the fea. Some of thefe on the 

 fhores of the Frith of Forth are very well 

 known, and have been often mentioned. In- 

 deed, on the fhores of that frith, many monu- 

 ments appear, v/hich would feem to carry the 



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