From now about 6, 000 years ago of the Jomon period the previous fiscal year, melting glaciers due to climate warming of the global scale, sea level rises close to 10m, the coastline had penetrated deep into the land. Middle Jomon period since the second half, the climate is colder coastline will begin to retreat gradually.
Is the location where you land of with the retreat of the coastline alluvial plain is formed, also where the sea has been left behind, it will become the tidal flats and lakes. Through the early from around the end of the Jomon Yayoi era, these offlap is believed to further advanced.
Emergent wetlands and alluvial plains by regression sea became a great arable land for the early paddy rice cultivation. Settlements will now advance to the plains from the plateau. With the start and progress of rice, it will be a large-scale deforestation is carried out. Farm tools necessary to carry out the rice, the demand of the sheet pile, such as wood needed to make the paddy fields will increase by leaps and bounds. Northern Kyushu is also the bold type clam blade stone axes of Fukuoka Prefecture Imayama production necessary in order to cut down trees became popular in a wide area in the provinces, it would be a sign of this situation. Deforestation, Yayoi era since the mid of settlements will increase rapidly in the West of the plains, are considered went further progress.
However, such a logging caused the devastation of the forest, is not seen evidence that went decisively destroy the natural environment. Yayoi era is plowed to create a paddy field in the alluvial plain formed by the changes in the natural environment since the Jomon period, life settlements to low on the plateau of its vicinity, necessary for life from the forest toward the mountain from behind the hills of obtaining only of wood and materials, this was a true long era prototype of land use was born rooted in Japan.