181-1.] An Account of the Basalts of Saxony. 143 



earth while at the bottom of the sea, and that it was afterwards 

 raised up to its present height by some unknown but powerful 

 natural agent, to which all the present mountains on the earth's 

 surface owe their elevation. It was in order to determine, by an 

 appeal to facts, which of these opinions is supported by the 

 strongest evidence, that Daubuisson was induced to examine the 

 basalt of Saxony, and to compose the present work. 



Most of our readers, we presume, are acquainted with the stone 

 to which the name basalt is applied by mineralogists. It has a 

 greyish black colour; and when polished, a bluish aspect. Some- 

 times it has a slight shade of green or brown. It occurs in beds, 

 and usually occupies the summit of mountains. Its fracture is dull, 

 and almost earthy, but fine-grained. It often presents distinct 

 granular concretions. It is difficultly frangible. It has a tendency 

 to form six-sided irregular prisms, some very striking examples of 

 which may be seen in the county of Fife. Its hardness varies. 

 Sometimes it strikes fire with steel, in which case it has a con- 

 choidal fracture ; sometimes it may be scratched with a knife. Its 

 specific gravity is about 3 - 06\5. It usually affects the magnetic 

 needle. When exposed to the weather it gradually crumbles down 

 into a fine black mould, which constitutes a very fertile soil. It is 

 to this rock that some of the richest parts of Scotland owe their 

 fertility. The only foreign substances usually observed in it are 

 crystals of basaltic hornblende, mica, felspar, augite, and olivine. 

 Sometimes it contains vesicles filled with green earth, chalcedony, 

 calcareous spar. In its composition it agrees nearly with green- 

 stone, a well known rock composed of felspar and hornblende, with 

 which it alternates, or into which it passes; and there is reason to 

 believe that both are composed of the same materials mixed in a 

 confused manner in the basalt, but symmetrically arranged and 

 crystallized in the greenstone. Fine specimens of basalt may be 

 picked up on the road near Edinburgh, especially towards Koslin ; 

 fur in that quarter rocks of basalt are often employed as materials 

 for mending tin.' road. They look exceedingly beautiful alter a 

 shower of rain, and can scarcely avoid attracting the eye of the 

 mineralogist. 



Daubuisson divides his work into five parts. In the first he gives 



definitions of the terms which he employs, and explains the nature 



<>t tlu- stones which occur in the basaltic mountains. In the second 



;ive« a description of the basaltic mountains of Saxony, such of 



them, at least, as he examined particularly. In the third he draws 



conclusions respecting the origin of the basalt in these mountains, 



founded on his preceding observations. In the Fourth he produces 



is to show that the Saxon basalt cannot be of \olcanic origin. 



And in tin- filth he fives us his inferences respecting basalt in 



ral. But these inferences he was afterwards induced to modify, 



by ! nination of Auvergne, v. here the rock occurs in situations 



(hat leem to leave no doubt about its volcanic origin. 



'1 he basaltic mountains in Saxouv which our author describes lie 



