The entire island is deeply incised by fjords, and the northern coast is extended by ice shelves - aprons of SEA ICE which are fused to the shore. The north is dominated by the Mountains of Grant Land, a jagged chain of sedimentary rocks some 100 000 years old, and shrouded in ice nearly 900 m thick - remnants of the last ICE AGE. Nunataks, or rock spires, project through the ice; Barbeau Peak (2616 m) is the highest mountain in eastern North America. The land descends southward to Hazen Plateau, dominated by Lake Hazen - the largest lake in the polar region. In central Ellesmere, mountains of the Central Ellesmere Fold Belt rise to 2000 m.
Ellesmere is distinguished by a spectacular landscape and an exceptional and fragile environment. Small herds of MUSKOXEN are dispersed across Hazen Plateau, along with the remnants of a CARIBOU herd decimated by Robert E. Peary in 1909 during his attempt to reach the NORTH POLE. There are numerous species of birds and several other land mammals, but coastal sea ice discourages marine mammals. Thirteen species of SPIDERS occur on Ellesmere Island. Though the climate is extreme, a peculiar "thermal oasis" at Lake Hazen produces surprisingly warm summers. The frost-free period at Tanquary Fiord averages 55 days. Ellesmere is a true polar desert, with only 70 mm of precipitation annually in some places. Consequently vegetation is sparse.