The Japanese government has lodged a protest with Russia over a geological survey in waters near the islands controlled by Russia and claimed by Japan.

Japan's foreign ministry says Russia had notified the Japanese side of a plan to carry out the survey from June 18 to September 18 in wide areas of the Sea of Okhotsk.

The International geological organization has decided to name a geological age represented by a 770,000-year-old stratum discovered near Tokyo "Chibanian."

A group of scientists, including those at Ibaraki University and the National Institute of Polar Research, filed a request with the International Union of Geological Sciences to register the stratum as a site representing a geological age.