The Mount Logan massif is crowned by an icefield that is more than 300 m thick in places. This icefield formed by the accumulation and compaction of snowfall over thousands of years. Because of its altitude the Mount Logan plateau was probably never much warmer than it is today, so the deepest ice layers there could be several hundred thousand years old. Ice is a plastic substance; it flattens and flows under the effect of gravity. Eventually some of the ice flows over the edge of the plateau as glaciers, or breaks into seracs above the steep sides of the mountain. But the high plateau of the mountain is so large (this is rare among mountains of the world) that some ice can remain trapped there for hundreds of thousands of years. How do scientists determine the age of ice? Read more...