These forests were on the equator, and the wetlands, which are always low-lying, stretched from North America in the west, through what is now Europe to China in the east, because these continents were all together at the time (Laurussia). The river plain which was the heart of the wetland stretched 5000km from eastern Canada to the Ukraine, and was 700km wide. This would make the Pennsylvanian basin larger than any wetlands on Earth today.