the Lower Carboniferous coals extend southwards as far as Scotland, Chemnitz and Moscow; the Middle Carboniferous as far as Brittany and Upper Silesia; and the Upper Carboniferous to western Auvergne, Baden, Brenner and Laibach. Even the Permian contains coal in France, Thuringia, Saxony and Bohemia, though only in the lowest beds immediately above the Carboniferous. The main mass of European coal is Upper Carboniferous, just as in North America, where likewise a shifting of the coal area from north to south is recognizable (Lower Carboniferous, New Brunswick to Virginia; Upper Carboniferous, Ohio to Alabama). But by the time of the Middle Permian indications of an arid area occur in place of coal. We therefore see in Europe a shifting of the coal-forming zone from Spitsbergen (in the Lower Carboniferous) towards Central Europe (Upper Carboniferous and lowermost Permian). No coals are known from the Upper Permian.
This displacement of the zone of equatorial rains shown by the occurrence of coal is beautifully confirmed by the similar shifting of the following northern arid zone, which is especially well shown by the deposits of rock-salt and gypsum.[1] Whilst it is in the Permian, the most recent formation considered here, that coal is absent, salt deposits are lacking in the oldest, that is, in the Lower Carboniferous. Rock-salt and gypsum are first found in the Upper Carboniferous of the Eastern Urals, north of the girdle of coal measures, and also already in Newfoundland, where it is above and therefore succeeding in time the coal horizons. Spitsbergen, according to Semper, had already a dry climate
- ↑ Information about deposits of rock-salt, which are so important for palæoclimatological purposes, is given by J. O. Freiherr von Buschmann, Das Salz, Vol. 2. Leipzig, 1906. Unfortunately the geological data as to their age are often quite incomplete.
