^ DOMAIN I. SIDEROUS. 



prismatic basalt with beds of basalt, or stony 

 and earthy matter without order; that of these 

 same beds of basalt with sand-stone, with car- 

 bonate of lime, or with coal, which are not 

 altered by it; in short, the presence of fossil 

 shells in some basaltic beds. The causes which, 

 in this hypothesis, concurred in the formation of 

 prismatic basalt, no longer existing, we see why 

 basalt is no longer formed in those vast currents 

 of lava which in our days have issued from vol- 

 canoes. It seems that it is with basalt, as with 

 veins, crystallised beds, fossils properly so called, 

 &c. Nature in her present quiescent state no 

 longer forms any*." 



The extent of these observations will be par- 

 doned, as there is not, in this science, a topic 

 more difficult or interesting : but we must now 

 return to a more immediate view of this cele- 

 brated substance. 



STRUCTURE I. AMORPHOUS. 



This rock, as already mentioned, is the trap of 

 the Swedes, who first recommended it to modern 

 notice ; while the basaltic columns of Saxony had 



* Brongniart, i. 473. He had observed, p. 470,' that lava enter- 

 ing the sea becomes fixed on the surface, and does not assume a 

 columnar form, which rather proceeds from slow cooling. 



