Tenneru Formation


The Tenneru Formation, sometimes in older literature the Tenneru Conglomerate Member of the Chorobetsu Formation, is a geological formation in southeast Hokkaidō, Japan, in the area of Kushiro. Deposited between the Harutori Formation and Yūbetsu Formation in the Urahoro Group that unconformably overlies the Nemuro Group in the Nemuro Belt, the Tenneru Formation correlates with the Rushin Formation at its western end. The Formation, laid down in the Late Eocene, consists mainly of reddish and reddish brown conglomerate, with some sandstone and mudstone; there are several intercalated coal seams. New species of fauna described from the Tenneru Formation include the "Kushiro tapir" :ja:クシロムカシバク|, and of flora, Actinidia harutoriensis, Alnus ezoensis, Aralia ezoana, Cordia japonica, Cupania japonica, Idesia kushiroensis, Lastrea kushiroensis, and Maesa nipponica.

Flora

The Tenneru Flora as described by Tanai Toshimasa in 1970 from the areas where the Tenneru Formation is exposed, with a thickness of some, along the upper stretches of the Tokomuro River in the western, comprises sixteen families and twenty genera, including two Pteridophytes, one Equisetum, and two conifers, the remaining species being dicotyledons: