LIGNITES. 323 



to exist rather in heaps of fragments than in proper 

 beds; but the descriptions of individual cases are im- 

 perfect and unsatisfactory. In the Isle D'Aix, the 

 accompanying substances are sands, marls, and cherty 

 flints, with quartz, agate, pyrites, and resinous sub- 

 stances. The wood is that of dicotyledonous plants, 

 and it is said that no palms have been found. This 

 wood is sometimes silicified, at others fibrous, or in 

 the state of jet. Fuci also are said to occur ; and 

 the shells are all marine, consisting of nautilites, pec- 

 tinites, gryphites, and others. With respect to these 

 fossils, the same general rule may be applied as in the 

 former case. 



The deposits of Lignite found in the strata which 

 succeed to the chalk, or in the tertiary formations, 

 have recently experienced considerable attention, par- 

 ticularly in France; though our knowledge of them 

 is still necessarily limited. Their geological connex- 

 ions suffice to distinguish them from those which 

 belong to the inferior strata, or to the alluvial forma- 

 tions; and their origin and causes are similar to those 

 of the animal remains in the same situations. It is 

 unnecessary to say that this lignite may occur in any 

 of the strata of such a series ; and equally unnecessary, 

 here, to give more than this general indication; as 

 the peculiar cases must be sought in local descrip- 

 tions. But in addition to the accompanying strata, 

 they are, in different places, attended by quartz, agate, 

 calcareous spar, sulphate of strontian, pyrites, and 

 hydrated iron ; together with amber, and imperfectly bi- 

 turninized resins, such as those of Bovey and Highgate. 



The lignites themselves are sometimes fibrous and 

 woody, while, at others, they pass into jet, and even 

 into coal; being, further, occasionally silicified. 

 Leaves and fruits occur, together with the woody 



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