Summary: Chemical analyses of the Lorne volcanic rocks show that the basalts and andesites are a closely related suite of lavas, notably rich in alkalis, especially potassium. The rhyolites of the Lorne area do not appear to form a continuous series with the more basic rocks. The various lava types are compared with the plutonic rocks of the area, and a relationship is suggested between the basic lavas and appinitic intrusions. The acid lavas are not comparable to granites in the area.

The late orogenic igneous activity in this part of the Caledonides therefore appears to involve three generations of magma, produced separately but within a short time of one another. The assumption that all the late Caledonian igneous rocks of the Scottish Highlands are differentiates of a common parent magma is not justified.