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nated peat-bogs of mountainous countries. With the 

 exception of mountain peat, every spot once denuded 

 remains naked, and therefore ceases to increase; while 

 it is refractory to vegetation in proportion to its com- 

 pactness. Thus do the excavations made for fuel re- 

 main for ever at a stand, except when, by retaining 

 water, they give rise to a new vegetation through aqua- 

 tic plants. And thence the practice, in rural economy, 

 of replacing the vegetating surface after excavating for 

 fuel ; under which the increase proceeds as before. 



Though I formerly alluded to the time necessary for 

 producing a given thickness of peat, the variations are 

 too great to allow of any general deductions, notwith- 

 standing the idle speculations of De Luc on this sub- 

 ject. On the continent, it is said that a depth of seven 

 feet was produced in thirty years ; while the often 

 quoted cases of Drumlanrig, Loch Broom, and Chat 

 Moss prove nothing, since the depths are not recorded. 

 It must indeed be plain, that no instance is a rule for 

 another ; since the fall of a forest may produce a thick 

 stratum in a short time, as the production in a fast 

 shoaling lake and a luxuriant marsh must differ from 

 that on a dry soil or in a deep water, as a small pit may 

 fill rapidly, and as a transported bog may form a deep 

 deposit in a single day. It is the same as regards cli- 

 mate : since he who should make a Dutch marsh the 

 rule for a Highland mountain, would produce conclu- 

 sions as valuable as De Luc or Rennie. Instead there- 

 fore of quoting cases, I shall suggest the necessity of 

 careful observation on the nature and origin of any 

 tract, before attempting to reason on its age ; as I 

 have sketched the preceding history, far too briefly 

 indeed for any other purposes than those of geology, 

 that I might clear the subject from all preceding mys- 

 tery and misrepresentation. Yet I must suggest, in 



