118 BERTHA'S VISIT TO HER 



brand of Iceland ; and I have some specimens of 

 the former, in which the fibres were flexible when 

 I took them out of the pit, though now hard and 

 brittle. From the disposition of those Bovey 

 lignites, whicli lie in alternate strata with clay 

 and gravel, it has been reasonably inferred that 

 the trees and vegetables of the adjacent moun- 

 tains were washed down at different periods into 

 a lake ; the clay and gravel, of course, sank first 

 to the bottom, and formed the floor ; but in time 

 the trees saturated with moisture, and pressed 

 down by an accumulation of other trees, sank 

 also ; and were again, perhaps in succeeding 

 ages, covered by successive depositions. 



" The common, or cubical coal, as it is called 

 from the shape into which it breaks, does not 

 bear the same obvious marks of vegetable origin 

 in its structure ; but where one species of coal 

 can be so clearly demonstrated to be only altered 

 vegetable matter, it would be bad philosophy to 

 ascribe the other species to other causes. In the 

 prodigious beds of coal, however, in Staffordshire^ 

 there is no want of vegetable traces ; and even in 

 the Newcastle coal the impressions of leaves and 

 branches are frequently found, as well as in the 

 freestone and slate-clay which intervene between 

 its numerous strata. At Kilsyth, in Scotland, a 

 very singular specimen was discovered; a tree 

 standing upright, with its roots resting on a bed 

 of coal, from which they could scarcely be dis- 



