The cache is at the western shore of a small rocky island... 5000 years ago. The island emerged from the sea about 6000 years ago. By about 3500 years ago it had merged with the neighboring small islands to the east and through them connected to the continent. A bit later, after the sealevel went further down, there was a stone-age settlement at the seashore below what was a hill-top at the western tip of a rocky peninsula (as evidenced by the stone age relics found at the edge of the cropfield to the southwest)
2000 years ago the sea had receded much further, and the former seabed to the west had turned to a fertile field. This land is in agricultural use still today.
(Kuva perustuu Maanmittauslaitoksen Maastotietokannan 06/2012 aineistoon. lisenssi)