Members are formally described within the Wandel Valley Formation (Early - Middle Ordovician) of the Ryder Gletscher Group in central and eastem North Greenland. In Peary Land the names Pyramideplateau Member (the combined lower and middle informal members of previous usage) and Vestervig Elv Member (the upper member) are proposed. In Kronprins Christian Land, the Alexandrine Bjerge Member (new) overlies the previously named Danmarks Fjord and Amdrup Members. Conodont studies, supported by the

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... acrofauna, indicate that the Pyramideplateau, Danmarks Fjord and Amdrup Members are of late Canadian (Early Ordovician) age. The Canadian-Whiterockian boundary lies within the lowermost part of the Vestervig Elv and Alexandrine Bjerge Members. The top of the former is of earliest Late Whiterockian age while the Alexandrine Bjerge Member only extends into the late Middle Whiterockian. The members of the Wandel Valley Formation are correlated with coeval successions in western North Greenland, East Greenland, the Canadian Arctic Islands and Svalbard.