 Over the last twelve thousand years during the Holocene epoch the most significant new geological features have been the deposits of peat, as well as in coastal areas that have recently been artificially drained such as the Somerset Levels, The Fens and Romney Marsh.Since humans began clearing the forest during the New Stone Age, most of the land has now been deforested, speeding the natural processes of erosion.Large quantities of stone, gravel and clay are extracted each year, and by 2000 11% of England was covered by roads or buildings.