Note 416 — Chapter XXIV · CARBONIFEROUS VOLCANIC PLATEAUX OF SCOTLAND

I formerly classed these eminences with the Puys, but I am now of opinion that they ought rather to be regarded as fragments of a long and somewhat narrow plateau. Their basic lavas and overlying sheets of porphyrite repeat the usual sequence of the plateaux, which is not met with among the Puys. But, as will be pointed out in the sequel, Arthur Seat in long subsequent time became again the site of a volcanic vent.