Mineralogy of Sky. tl 



mate and exposure, are still covered with unprofitable heath and 

 peat, producing a scanty and almost useless herbage. It is worth 

 our while to inquire into the causes of this difference, and to see if 

 valid ones cannot be assigned. 



In the land already under tillage it is obvious that the subsoil is 

 , covered with a soil actually in use, consisting of vegetable mould 

 annually loosened by the spade or plough, and admitting the pene- 

 tration of light, of air, and of water, to the subjacent and half de- 

 composed matter. In the uncultivated neighbouring tracts we shall 

 on the contrary find it covered with a thick mass of peat, the imme- 

 diate soil on which the heath, the sphagnum, the carlces, and the 

 rushes alternately flourish and die, adding fresh matter to this already 

 impenetrable substance. Neither air, light, nor water can make their 

 way through this dense covering of a substance so notoriously im- 

 pervious that it has been found of equal use with clay in puddling 

 the artificial banks of canals. It forms in fact an adventitious and 

 useless soil so entire and so impenetrable that it would be of 

 equally little consequence to the land-owner in its present state, 

 whether it where bedded on a rock of solid quartz or on the most 

 fertile garden mould. Fortunately this covering of peat is rarely so' 

 deep that the plough or the caschrom (the crooked spade, of the 

 Highlanders) cannot reach to the bottom of it. The remedy and 

 obvious method of improvement is pointed out by the relativa con- 

 dition of the fertile and the barren parts of this tract. The few exr 

 periments which have been tried have proved eminently successful, 

 and among them I may point out those performed by Mr. Mac- 

 pherson at Portree. By the admission of air and water the progress 

 of decomposition is accelerated, and the rock is reduced in no long 

 space to a useful soil. The texture of the peat is at the same time 

 loosened by its admixture with the decomposed rock, and being thus 



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