23S SCIENTIFIC NEWS. 



suitt? of 360 speciinens laid upon the table. — As the county 

 is in general deeply covered with soil, and profusely clothed 

 with vegetables, the detenninatioa of the different forma- 

 tions must have been a work of considerable labour ; and 

 the skill, judgment, and perseverance of the observer, must 

 have been fiequently put to the trial. The doctor, after 

 describing the physiognomy or external aspect of the coun- 

 ty, gave^ particular account of the diiFerent formations of 

 which it is composed. 1 hey are as follows; — transition, in- 

 dependent coal, newest floetztrap, and alluvial. When dc- 

 s*cribing the different transition rocks, he alluded particu- 

 larly to the supposed granite of Fassnett, (described by 

 Professor Pluyfuir in his Illustrations of the Huttonian The- 

 ory*), which he proved to be a stratified bed of transition 

 Newest floetj- '•^'''^^'istone. The descriptlyn of the rocks of the newest 

 trapioriTitttJou. floetz-trap formation was particularly interesting, not only 

 on account of the beautiful transitions he pointed out, but 

 also as it proved the existence of a considerable tract of these 

 rbcks in Scotland, where their occurrence had been dis- 

 puted. He enumerated and described the following mem- 

 bers of this formation: — traptuff, amygdaloid, clay-stone, 

 basalt, porphyry slate, and porphyry slate inclining to green- 

 stone. He found the traptuff, which is a coarse mechanical 

 deposit, forming the lowest member of the series, and rest- 

 ing immediately on the coal formation: on this tuff rests 

 amygdaloid containing fragments: above this amygdaloid is 

 common amygdaloid free of fragments ; this, in its turn, is 

 covered with basalt : the basalt gradually passes into and is- 

 covered with porphyry slate : and the porphyry slate, in some 

 instances, appears to pass into greenstone, which forms the 

 uppermost portion of the formation :-^so tliat we have thus 

 a beaiitiful series of transitions from the coarse mechanical, 

 to the fine chemical ; that is, from traptuff to porphyry slate 

 jiieliuing to greenstone. The doctor also remarked, that 

 the amygdaloid contains crystals of feldspar which have an 

 earthy aspect; the basalt, crystals of feldspar possessing the 

 characters of common feldspar; and the porphyry slate, 

 glassy feldspar; — facts which coincide with,^ and are illus- 

 trative of the increasing fineness of the sptivtion, from the 



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oldest 



