4Si 



me above another, but accumulation* of extcnfive bafalt ftrata ? and, I dare 

 fay, his perpendicular faces, like thofc with us, enable him to obfervc the 

 uniform thicknefs which each flratum preferves in its whole extent,* and 

 the confummate regularity with which the mafs is arranged. 



Mr. Playfair fays, that Mr. Kirwan did not view nature with his owa 

 eyes ; I am curious to know, with whofe eyes he himfelf difcovered bafalt 

 to be an unftratified fubftance ; had I not met with the paflage I have quoted, 

 I fliould have been tempted to doubt the evidence of ray own. That the rea- 

 der may not remain in a doubt between us, I fliall appeal to the teftimony of 

 my friends, and requeft, before he decides, he will examine the iketches 

 Captain O'Neil has given, of portions of the ftrata of Plejkin and Port 

 Spagna, and ftill more the view of the magnificent fa9ade half a mile 

 farther eaftward, and the view of the precipice at Cave-hill above Bel- 

 fast, taken by my friend Captain Chapman ; and I can aflure him thefc 

 were all taken before either I, or my friends, fufpefted any naturalift would 

 be fo hardy as to fupport his fyftem by denying the ftratification of bafalt. 



Mr. Playfair is pleafed to dwell minutely on the foffils of Port- 

 rufh Promontory, and their arrangement, which laft he has never 

 feen: he fays the fliells found there in bafaltic rocks, have been 

 «f late much infifted on as a proof of the aqueous formation of 

 tbefe rocks ; and again, " thefe fpecimens with fhells were fuppofed 



Vol. I£. ( 3 P ) " be 



* From this rule the uppermoft Ilratuin mud always be excepted, for, Avhile the plane 

 bounding its lower Cde is invariably reftilineal, and parallel to the mafs of the ftrata 

 below it, its upper fide partakes of all the inequalities of the furface, and is perpetually 

 undulating or Hoping away to a point, where the ftratum vaniflies ; the inequalities 

 inftantly transferred to the ftratum next to it, now become the uppermort, follow the 

 former ftratum in the contrary direiflion, and another will, probably, foon appear oyer it, t9 

 which the irregularities will be transferred. 



The confufed manner in which bafalt is difpofed on the furface, might miHead cur- 

 fory obfervers, but Mr. Playfair, by his own account, has perpendicular faces where the 

 errangement of the ftrata mull neceffarily be difclofed. 



