Here, the bedrock is largely sedimentary, covered with moraine (boulders and other debris deposited by glaciers). The drifting North Magnetic Pole is located in this western part of the ecozone, and Thomsen, the most northerly navigable river on earth, winds its way to the M’Clure Strait through a deep valley at the centre of Aulavik National Park, on Banks Island.

East of these islands, the terrain is made up mainly of plateaus (such as the one on mainland Melville Peninsula), and of gently rolling, rocky hills that rise to almost 1000 metres in the central uplands of Baffin Island, close to the Barnes Ice Cap. In this eastern part of the ecozone, the bedrock is mainly Precambrian – very old, hard, and granitic – and permafrost (permanently frozen subsoil) grips the land here and throughout the region. Off shore, the sea is ice-bound all year in the northern half of the Northern Arctic. In the southern half, the waters are open in the summer, but with lots of pack ice still around.

The mean summer temperature in this south-