DBTIKG DP OP BOGS. 91 



pletely fill up the space occupied by the water, and the surface is 

 gradually converted from a pond to a quaking morass. The morass 

 is slowly solidified by vegetable production and deposit, then very 

 often restored to the forest condition by the growth of black ashes, 

 cedars, or, in southern latitudes, cypresses and other trees suited to 

 such a soU, and thus the interrupted harmony of Nature is at last 

 re-established." 



In continuation of the passage I have cited, Mr Marsh goes on to 

 say, " In countries somewhat further advanced in civilization than 

 those occupied by the North American Indians, as in mediaeval 

 Ireland, the formation of bogs may be commenced by the neglect 

 of man to remove from the natural channels of superficial drainage 

 the tops and branches of trees felled for the various purposes to 

 which wood is applicable in his rude industry ; and when the flow 

 of water is then checked, nature goes on with the processes I have 

 already described. In such half-civilised regions, too, wind-falls are 

 more frequent than in those where the forest is unbroken, because when 

 openings have been made in it for agricultural and other purposes 

 the entrance thus afforded to the wind occasions the sudden over- 

 throw of hundreds of trees which might otherwise have stood for 

 generations, and have fallen to the ground only one by one, as 

 natural decay brought them down. Besides this, the flocks bred by 

 man in the pastoral state keep down the incipient growth of trees on 

 the half -dried bogs and prevent them from recovering their primitive 

 condition." 



Denmark supplies many illustrations of the efiect of vegetation, 

 herbaceous and arborescent, in filling up and drying up marshes in 

 prolonged periods extending back into pre-historic times. 



By numerous successive growths of aquatic and semi-aquatic plants, 

 herbs, and trees, bogs have there been filled np and dried up in the 

 course of ages, and at length rendered, as now, so dry as to be fit 

 habitation for man. And simultaneously with what has been 

 effected by the abstraction of water by the spongioles, and emission 

 of it by the stomates, an influence modifying the process of desiccation 

 otherwise produced, intensifying or moderating it, may have been 

 going on. 



Marsh, citing as his authority a work by WUhelm, entitled " Der 

 Boden und das Wasser,'' a work published in Vienna in 1861, and a 

 work by Krecke, entitled " Het Klimat van Xederland," says: — The 

 relative evaporating action of earth and water is a very complicated 



