DR. A.NGUS SMITH ON PEAT. 315 



terially in its appearances and properties in proportion 

 to the depth at which it lies, on the upper surface covered 

 with moss of various species, and to the depth of about ten 

 feet composed of a mass of the fibres of similar vegetables 

 in different stages of decomposition proportioned to their 

 depth from the surface, generally, however, too open in 

 their texture to be applied to the purposes of fuel; below 

 this generally lies a light blackish brown turf, containing 

 the fibres of moss still visible, though not perfect, and ex- 

 tending to a further depth of perhaps ten feet under this. 

 In the instance exhibited in the Section at the close of Mr. 

 Griffith's Report, are found small branches and twigs of 

 alder and birch ; but we do not understand him as being 

 of opinion that such is by any means generally the case. 

 At a greater depth the fibres of vegetable matter cease to 

 be visible, the colour of the turf becomes blacker, and the 

 substance much more compact, its properties as fuel more 

 valuable, and gradually increasing in the degree of black- 

 ness and compactness proportionately to its depth : near the 

 bottom of the bog it forms a black mass which, when dry, 

 has strong resemblance to pitch or bituminous coal, and 

 having a conchoidal fracture in every direction, with a 

 black shining lustre, and susceptible of receiving a con- 

 siderable polish." 



P. 1 6. Mosses. — "Of the growth of moss in stagnant 

 waters there are numberless instances ; and in fact through- 

 out the whole of the clay-lands in this part of the country, 

 wherever water is suffered to remain any length of time, 

 an incipient formation of bog (by the growth of aquatic 

 mosses) is the invariable consequence. 



"It has been supposed by some, that the whole of the 

 country now covered by bog had formerly been forests, 

 which having been either entirely or partially destroyed by 

 fire, currents of water, or otherwise, the wreck of these 

 forests falling in various directions had caused an interrup- 



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