Carboniferous forest. Computer animation showing forest in the Carboniferous period (approximately 360-300 million years ago). The period is named because of the large northern European coal deposits which were laid down during that time. Moist tropical equatorial areas produced lush plant growth, with fern-like (but seed-bearing) pteridosperms, large Lepidodendron trees and tall mangrove-rooted Cordaitales all abundant.