• Kyodo


Japanese researchers have applied to have a new geological age based on ancient strata in Chiba Prefecture named “Chibanian.”

The strata illustrate the Earth’s most recent switch in magnetic poles during a period from 126,000 to 770,000 years ago. The period has been proposed as a candidate for a Global Boundary Stratotype Section Type and Point, or GSSP.

GSSPs are reference points used to show the boundaries of a geologic time scale. If approved by the International Union of Geological Sciences, it would be the first time a Japanese location name has been used for a GSSP, the research team said Wednesday.

The international scientific society will begin a review of the Chiba strata and two candidates in Italy called the Montalbano Jonico and Valle di Manche sections this summer. The winning strata might be announced early next year.

The three candidates are competing for the naming rights to the period in which the Earth’s north and south magnetic poles last switched.

“We have collected data and written the application with simple expressions,” said Makoto Okada, a team member and a professor at Ibaraki University. He said it might be the last chance for a Japan-related name to be used for a geological age.

The researchers represent 22 Japanese universities and institutions, including the National Institute of Polar Research and Chiba University.

The Chiba stratum is exposed on a cliff in Ichihara, along the Yoro River on the Boso Peninsula. In the stratum, minerals found in good condition show that magnetic north and south last switched 770,000 years ago.

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