The age of the glacial deposits is later than the Glossopteris flora and occurs early in the time of the Gangamopteris flora.
Starting with the Permo-Carboniferous vegetation, and omitting for the moment the Glossopteris flora, we find a comparatively homogeneous flora of wide geographical range, consisting to a large extent of arborescent lycopods, calamites, and other vascular cryptogams, plants which occupied a place comparable with that of Gymnosperms and Angiosperms in our modern forests; with these were other types of the greatest phylogenetic importance, which serve as finger-posts pointing to lines of evolution of which we have but the faintest signs among existing plants.
In the southern hemisphere the Glossopteris flora succeeded a Lower Carboniferous vegetation with a rapidity similar to that which marked the passage in the north from Palaeozoic to Mesozoic floras.
It was from this Glossopteris flora that several types gradually migrated across the equator, where they formed part of the vegetation of more northern regions.
The difference between the Glossopteris flora and those which have left traces in the Upper Gondwana rocks of India, in the Wianamatta and Hawkesbury beds of Australia, and in the Stormberg series of South Africa is much less marked than that between the PermoCarboniferous flora of the northern hemisphere and the succeeding Mesozoic vegetation.