254 Geology — Si. Helena, and County of Antrim. 



that is, between the strata of columnar basalt, alternating with 

 them in every variety of thickness. 



I have in the Transactions of the Royal Society given a minute list 

 of the strata composing the promontory of Bengore. The mag- 

 nificent stratum forming the upper range of pillars at Pleaskin, 

 fs the tenth, counting from the sea — this is surmounted bv an- 

 other stratum of massive pillars, (the eleventh,) of greater dia- 

 meter, coarser material, more imperfect workmanship, and much 

 shorter. 



We have different views of portions of these strata, from Dun- 

 severic to the cascade at Portmoon, where the upper one is taken 

 away for a mile; it appears again at the depression west of 

 Plcaskin, and is often seen for another mile, always resting on 

 the tenth; and wherever the junction is exposed, these strata 

 pass into each other per sulium, without interrupting the so'idity 

 or continuity of the material: so that I have no doubt, could we 

 quarry (as we often do at the junction of other strata), the stones 

 would not break at that junction, but we would find masses con- 

 taining the junction, and portions of each stratum adhering so- 

 lidly. 



After being thus connected for nearly three miles, without any 

 interruption of their continuity, as they arrive at the western 

 point of Port Knoffer, almost innnediately above the Giant's 

 Causeway, they are separated for a short space by a laver of 

 scoria and cinders placed between them, as happens so often at 

 St. Helena. 



There is another remarkable feature in which St. Helena ex- 

 hibits strong marks of having been acted on by intense fire, to 

 which I find nothing similar in our basaltic country; — the heat 

 has been so violent between the basaltic strata, as to act on the 

 ends of pillars terminating them, without affecting the middle 

 of the strata. — Hear what our author says: 



" The middle of the rock, where it has not been injured bv 

 time, or the effects of fires." 



" We can generally trace somewhat of the columnar appear- 

 ance yet, from the scorification of their bases and summits." 



'* The summits and bases of the basaltic rock are always 

 more or less scorified, cellular, and honeycombed." 



'* The bases and summits of the columns are so black and 

 scorified, that t'ley look like trunks of trees burnt to charcoal 

 at each end." 



These facts are of extreme importance, when we direct our 

 speculations to original formation and arrangement ; for, first — 

 in respect to the long received opinion, that basaltic pillars are 

 of igneous formation: it now appears, that in St. Helena, the 

 action of intcnae heat, i:i situ, has tended, so far as it could 



reach, 



