Judging from strata and other evidence, the history of Izu Peninsula can be traced to approximately 20 million years ago.
About 20 million years ago, Izu was a group of submarine volcanoes located several hundreds of kilometers south from Honshu, the main island of Japan.
Submarine volcanoes and volcanic islands formed on the Philippine Sea Plate together with the plate itself moved north, eventually colliding with Honshu and forming the present shape of the peninsula. This happened approximately 600,000 years ago.