Tentative biostratigraphic correlations, based on marine faunas, have been made by various workers between Ufimian and Kazanian sequences in their type areas in the Volga–Urals region of Russia and Roadian and Wordian sequences in their type area in Texas, United States. Unfortunately, palynological correlation between the Russian and United States sequences is not possible, due to lack of data from the latter. However, detailed palynological data are available from rocks of Roadian and Wordian age in the Canadian Arctic Archipelago, and therefore indirect correlations are possible. Palynomorph assemblages from the Canadian Arctic and other circumpolar areas, such as the southern Barents Sea and Greenland, are different from those of the Ufimian and Kazanian Russian sequences in their type areas. This is likely to be the result of variations in the parent flora in response to significant paleoclimatic differences. For example, the climate of the Volga–Urals region in Late Permian times was probably hot and arid, whereas that of the Canadian Arctic, Barents Sea, and Greenland was cooler and probably more humid.