Baltica data makes it difficult to locate the margin in the Arctic. Ordovician faunas indicate that most of Svalbard, including Bjørnøya, was part of Laurentia, but Franz Josef Land and Kvitøya (an eastern island of the Svalbard archipelago) most likely became part of Baltica in the Timanide Orogeny. The Taymyr Peninsula, in contrast, never was part of Baltica: southern Taymyr was part of Siberia whilst northern Taymyr and the Severnaya Zemlya archipelago were part of the independent Kara Terrane in the early Palaeozoic. The eastern margin, the Uralide orogen, extends from the Arctic Novaya Zemlya archipelago to the Aral Sea. The
Severnaya Zemlya of the Severnaya Zemlya group and is separated from Komsomolets Island by the Yuny Strait. Pioneer island measures in area. This island houses the Pioneer Glacier. Thelodonti fossils from the Upper Silurian have been found in the island. Off Pioneer Island's southwestern end lies Krupskoy Island. This is a fairly large island, over in length and about in width. The sound that separates it from Pioneer is only in width. This island should not be confused with Pioneer Island in Canada (). Schmidt Island, measuring , is located at the far northwestern end of the archipelago. This island is quite