HELVETII (`EXouirtot, `EX/3 TTtot), a Celtic people, whose original home was the country between the Hercynian forest (probably the Rauhe Alp), the Rhine and the Main (Tacitus, Germania, 28).
Th massif is in fact merely a fragment of the great Hercynian niountair system which was formed across Europe at the close of the Carboni ferous period.
The "Hercynian " earth-movements, which so profoundly affected north-west and north-central Europe at the close of Carboniferous times, gave rise to a series of east and west folds in the Irish region.
The Triassic beds rest on the various Carboniferous series in turn, indicating, as in England, the amount of denudation that followed on the uplift of the Hercynian' land.
The whole mass evidently belongs to the ancient Hercynian chain of North Europe (which, indeed, derives its name from the Harz), and is the north-easterly continuation of the rocks of the Ardennes and the Eifel.