*^84 ORIGIN OF BASALT- 



facts ^nd ob- Long Glibcrl, near the eastern extremity of the calcareous 

 scrvatjons re- facade, a mile from Portrush, we find, half way up the preci- 

 jn the county pice, a vast basaltic rock, inserted in the middle of the lime- 

 pf Antrim ; ad- stone mass, and, at the contact, so united to the lime-stone, as 

 duced to. show ^ , ■ \ -,. ■, ,. t-j 



that ,it d.s not to >orm, vviih it, bat one solid mass. c. 



voicaiiic. The peninsula of Kenbaan, near Ballycastle, is the spot 



where bn^alt and lime-slone come in contact in every possible 

 way. Piece:^ot' lime-stone of all sizes, imbedded in the basal- 

 tic mas'?, and similar fragments of basalt, dispersed in like man- 

 ner through the lime-stone, and, in the precipice above, strata 

 of basalt, and lime-stone alternating. Here the opportunities 

 of examining the contact of ba?alt and Ilme-stone are number- 

 less; and, on ev^ery occasion, I found them united solidly; 

 the line of deirarcation correct, as if drawn by a pencil ; not 

 the least trace of calcination, such as might be expected from 

 the calcareous matter, coming in contact with so glowing a 

 mass, as this theory supposes our basalt to have been.* 



This unexpected circumstance has somewhat embarrassed 

 the \olcanists; who, to account for it, have been driven to 

 various exertions of their ingenuity : but not one of them seems 

 ever to have inquired what was the result, when calcareous 

 matters came in contact with actual lava, as it flowed. Here 

 an obvious mode presents itself, of deciding the question, whe.- 

 ther basalt and lava have a common origin: for, if iheir con- 

 tacts with calcareous matter produce the same effects upon it, 

 we have a.-strong presumption in favour of the affirmative. On 

 the contr&ry, should the efVects turn out to be totally different, 

 we have a conclusive argument in support of the negative. 



Whether this mode of bringing the question to issue did not 

 occur to the gentlemen who support the volcanic origin of 

 basalt, or whether they did not like to commit a favourite 

 theory to so rude a test, I will not presume to conjecture. 

 Direct evidence, with a. view to the question, I admit I have 



none; 



* The result of my observations, on the contacts of basalt and lime- 

 stone, perfectly correspond with those of Mr. St. Fond, in Vivaiais 

 (Min. des Volcans, chap. 13.) Dr. Hamilton, I admit, saw things ia 

 a different point of view : but as he does not refer us to the places 

 where he examined these contacts, I cannot brjng the point to issue 

 in my country. 



