Source : Webster's Revised Unabridged Dictionary (1913)

Glaciation \Gla`ci*a"tion\, n.
   1. Act of freezing.

   2. That which is formed by freezing; ice.

   3. The process of glaciating, or the state of being
      glaciated; the production of glacial phenomena.

Source : WordNet®

glaciation
     n 1: the condition of being covered with glaciers or masses of
          ice; the result of glacial action; "Agassiz recognized
          marks of glaciation all over northern Europe"
     2: the process of covering the earth with glaciers or masses of
        ice