Most geologists are aware that the Chalk of Antrim, although full of flints and fossils like those in the English Chalk, is a hard splintery limestone, known here as the “White Limestone.” Its induration is often attributed to the action of the basaltic covering which spreads over it, and the coincidence of the two things is certainly remarkable; but I think I can now show that they are not connected in the way of cause and effect.