459 



rangement is interrupted at Dunhtce for about a mile, by a precipice of 

 ftratified white limeftone, near 1 50 feet liigh. 



Tiie range of perpendicular precipices is terminated at MagH/igan Rock, 

 by a beautiful fa9ade 180 feet high, on the fummit of a mountain, and 

 compofed of fix and feven ftrata of rude columnar bafalt, elevated near 

 2000 feet above the furface of the fea near it. 



However entertaining this magnificent, and perpetually fliifting fcenery 

 may be to the fpeftator, I fear the reader will think the detail tire- 

 fome ; I flrall therefore limit my obfervations on the flratification of 

 thefe precipices, to fuch circumftances alone as feem to apply direftly 

 to Dr. Hutton's theory. 



The (trata in this whole range are horizontal, or nearly fo, and in 

 the fame fpot all fteadily parallel to each other, except at Fairhead 

 alone, where the ftrata of freeftone and coal are inclined to the hori- 

 zon, in a greater angle than the incumbent ftratum of columnar bafalt. 



Every ftratum, according to Buffori% rule, feems to preferve an uniform 

 thicknefs through its whole extent, and to be of precifely the fame 

 nature in its whole thicknefs, with one exception ; the variety of bafalt, 

 called for diftinftion, irregular Prifmalic, is at its lower edge formed 

 into fmall prifms, fliooting in various direftions, while its upper part is 

 amorphous, f 



By examining thefe accumulations of ftrata in a vertical dlredlion, wc 

 find the impofllbility of their having been formed as Dr. Hutton fup- 

 p ofes, ftill more decided ; for whether by their nature they approximate 

 to each other, as in the feveral varieties of bafalt ; or whether they be 

 totally different, ■&.% Jandjlone., coal, limejlone, bafalt ; yet in all cafes the 

 tranfition from one ftratum to another, is per faltum, and never per 



( 3 M 2 ) gradut, 



f I have, in the Tranfaftions of the Royal Society, Edinburgh, given, (amongft feveral 

 varieties of bafalt, hitherto unnoticed) a particular account of this fpecies, which I call 

 irrfgular prifmatic ; it feems to accompany the columnar bafalt in moft countries, their ftrata 

 ^generally alternating. 



