A group of Japanese researchers say they have unearthed the oldest rocks ever found in the country. They say the 2.5-billion-year-old rocks are a window on the formation of Japan's islands.
The team, led by Yasutaka Hayasaka, an associate professor at the Graduate School of Science at Hiroshima University, announced its findings on Monday.
The rocks were found at two areas in Shimane Prefecture, western Japan, in 2017. Researchers concluded they were made of magma that solidified some 2.5 billion years ago under the earth's crust.
The previous record holder was a 2-billion-year-old rock found in 1970 in Gifu Prefecture, central Japan.
The researchers say the rocks come from a time when Japan's islands were connected to the Asian Continent.
They say the findings are significant for studying how the archipelago was formed.