"In ancient Greece, claims Ponting, something similar occurred. Cutting down forests for fuel and for shipbuilding caused erosion, leaving just a thin topsoil in much of Greece. This explains why olives are such an important crop in Greece still today. Olive trees, unlike most other trees, can take root and thrive in thin, poor soils. Plato himself, in the fourth century BCE, lamented this devastation of his homeland Greece: What now remains compared with what then existed is like the skeleton of a sick man, all the fat and soft earth having wasted away, and only the bare framework of the land being left. (Plato, Critias, quoted in Ponting 1992:76)