This a cabbage farm in Jeju Island of South Korea. As Jeju has a windy and rainy climate with mostly stone-filled and porous volcanic ash for soil, the Jeju farmers face a constant challenge. Before plowing and planting a field, the Jeju people had to first clear away the stones in the fields. They then used these abundant lava rocks to build fences, which served multiple functions, but mainly as windbreakers preventing soil erosion.