In the Yubari district, the Yubari formation contains several coal seams of superior quality.(Table 1)Among them the distribution of “the 10-shakuso”is most extensive.From the standpoint of depositional features, this district may be divided into three zones, namely the western zone, the central zone and the eastern zone.During deposition of the Yubari formation and etc., the depression in the central zone was greater than that in the other two zones, and splitting up of coal seams is found inthe central zone.