MODE II. BASALT, 



STRUCTURE II. COLUMNAR. 



The following passage of Strabo has beeri 

 thought to imply columnar basalt : 



" We went to Philoe from Syene in a carriage^ 

 through a level plain, the space of a hundred sta- 

 dia. Along almost all the route were to be seen, 

 on both sides, in many places, as it were terms*, 

 of a hard, round, and polished stone, almost spheri- 

 cal, and of which mortars are commonly made, 

 placed upon a larger stone, and surmounted by 

 another. Some even lay apart ; the largest being 

 not less than twelve feet in diameter, and the 

 : others about half as large f." 



Several authors have inferred from this passage 

 that Strabo means to speak of columnar basalt, 

 but he would rather seem to imply a work of art, 

 a magnificent avenue from Ethiopia into Egypt. 

 No basaltic columns have been observed twelve 

 feet in diameter ; and even if the passage be cor- 

 rupt, and twelve feet in height be intended, or 

 perhaps two feet in diameter, it would still remain 

 so obscure, that it would be adventurous to build 

 any solid argument upon such an uncertain found- 



* The little hermetic columns at Athens, 

 t Strabo, lib. 17. 



