Operation Napoleon

It's 1945: a German bomber flies over Iceland in a blizzard; the crew have lost their way and eventually crash on the Vatnajokull glacier, the largest in Europe. Puzzlingly, there are both German and American officers on board. One of the senior German officers claims that their best chance of survival is to try to walk to the nearest farm and sets off, a briefcase handcuffed to his wrist. He soon disappears into the white vastness. 1999, mid-winter, and the US Army is secretively trying to remove an aeroplane from the Vatnajokull glacier. By coincidence two young Icelanders become involved - but will pay with their lives.  

Beyond The Gap by Harry Turtledove

Beyond the Gap (2007) is a Prehistorical Fantasy. The Glacier had been covering the northern plains forever. Only myths tell of a time before this mountain of ice. Legends also speak of a Golden Shrine -- sacred to the gods -- on the other side of the Glacier, but few believe these old tales. The Glacier had been retreating even before the founding of the old Raumsdalian Empire. Over the centuries, a gap in the great Glacier has been extending further north.