The evolution of trees and forests through the Devonian Period fundamentally changed the Earth’s land biosphere, as well as impacting physical environments and geomorphology by stabilizing sediments and interacting with flowing air and water. In this talk I will describe a recently discovered forest landscape within the Middle Devonian (Eifelian) Hangman Sandstone Formation of Somerset and Devon. New fieldwork has shown that this unit contains the earliest fossil evidence for trees in the British record, as well as the oldest known evidence globally for the relative position of standing trees: in common parlance, a fossil forest.

These findings provide evidence that the Eifelian Stage of the Devonian (393.3-387.7 Ma) marks the onset of tree-driven changes to physical environments that would forever change Earth’s non-marine landscapes and biosphere.