77 



origin of basalt, are so ready to give this fossil pores and 

 bladder holes. For my own part, I never met with, in any 

 of our basalts, internal caA'ities; except such as once con- 

 tained water, or those from which zeolites had fallen out; 

 and even these very rarely. 



I shall now proceed to two other facts, which seem to 

 countenance the volcanic origin of basalt. 



The fii-st is stated by Dr. Troil, who observed in Ice- 

 land, as he tells us, " basalt pillars, peeping out from 

 " among the lava, and still oftener from among the tuta." 



Iceland is, unquestionably, both a basaltic, and a A'olca- 

 nic country. The question to decide here, is: were these 

 pillars formed out of the materials, among which they 

 appeared.? or, was the coincidence accidental.'' Now, as 

 I apprehend, no one will maintain, that the tufa Avas 

 formed into basalt pillars; they must necessarily have been 

 enveloped by the tufa, that fell among them. The reader 

 is, then, to determine, upon these scant" data, (for Ur, 

 Troil does not give much assistance,) if ic be not proba- 

 ble, that the pre-existing basalt was enveloped by the 

 lava, as well as by the tufa; and if so, the original ques- 

 tion rests as it stood. 



The only remaining fact, that has come in my way, that 

 seems to apply to this question, is related by Abbe Spa- 

 lanzani. He found, at the bottom of the crater of Vol- 

 cano, in the Lipari Islands, " pentagonal basalt prisms. On 

 •" looking up the sides of the crater, he perceived, they 

 " came from a great bed of lava, almost vertical; divided, 



voi,. X. I, " in 



