Palynological evidence for Pennsulvanian extra-basinal vegetation in Atlantic Canada

Pollen preserved in latest Westphalian and early Stephanian clastic deposits of the Sydney Coalfield, Cape Breton Island, suggest that there were zones of different vegetational habitats surrounding the wetlands where the coal-forming peat was formed. On the margins of the wetlands was a narrow band with large cordaitanthacean trees. This was surrounded by ‘occasionally dry' habitats supporting Schuetzia-plants, ruflorioid-plants and Aethophyllum-like herbaceous conifers. Around this were mesic or seasonally dry habitats, dominated by walchian conifers and disaccate-producing peltasperms. These in turn were surrounded by xeric or seasonally wet habitats, dominated by ullmanniacean-like conifers, cycads and monosaccate-producing peltasperms. During latest Westphalian and early Stephanian times, the mesic and xeric habitats encroached nearer the wetlands, although the vegetation of the wetlands themselves remained essentially unaffected. This vegetation change was not a response to climate change, but probably to changing drainage patterns and topography in the surrounding hinterland. The Florinites-producing cordaitanthaceans appear not to have been upland trees, as previously suggested, but occupied mainly coastal habitats, or riparian habitats on the margins of the wetlands.