With the map at left, you can see the coastline as it would have appeared during the pre-Jomon period or incipient phase of the Jomon period. At that time, the sea lay far below the area that is now Osaka Bay, and this area would have been a relatively warm valley, occupied by people. By 7,000 years BP (map at right), the sea rose to about 3 m above the present level, and covered most of the area now occupied Osaka City. At this time the average temperature for the area was about 2 degrees centigrade warmer than those today. After this, the sea dropped to the present level (by about 1,000 BC).

Much of what is now central Osaka remained sub-merged until the 5th century AD, before being artificially drained, filled in. and built up, to create the present irregular outline of Osaka Bay. It is likely that most of the land area occupied during the earliest Jomon period is now underwater. Has any underwater archaeology been attempted in Osaka Bay? Please tell us if you hear of anything.

(Maps by MS, text by MS & PJM, Jan. 2003, 8th anniversary of the Hanshin earthquake).