* t a 



to8 ILLUSTRATIONS OF THE 



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ever thefe |afl are found undifturbed, and from 

 the deftrudion of fuch beds they have no doubt 

 originated. Hence a great thicknefs of chalk 

 mull have been decompofed, to yield the quan- 

 tity of flints now in the foil of thefe countries \ 

 for the flints are but thinly fcattered through 

 the native chalk, compared with their abun- 

 dance in the loofe earth. To afford, for ex- 

 ample, fuch a body of flinty gravel as is found 

 about Kenfington, what an enormous quantity 

 of chalk rock mufl: have been defliroyed 



105. This argument, which Dr Hutton has 

 applied particularly to the chalk countries, 

 may be extended to many others. The great 

 plain of Crau, near the mouth of the Rhone, is 

 well known, and was regarded with wonder, 

 even in ages when the natural hiftory of the 

 globe was not an objed of much attention. The 

 immenfe quantity of large round gravel- ftones, 

 with which this extenlive plain is entirely co- 

 vered, has been fuppoled, by fome mineralo- 

 gifl:s, to have been brought down by the Du- 

 rance, and other torrents, from the Alps ; but, 

 on further examination, has been found to be of 

 the fame kind that is contained in certain hori- 

 zontal layers of pudding-fl;one, which are the ba- 



ils of the whole plain. It cannot be doubted 



therefore, that the vaft body of gravel fpread 



over it, has originated from the deflrudion of 



layers 



^k 



