NOUN (2)

1. the condition of being covered with glaciers or masses of ice; the result of glacial action;
- Example: "Agassiz recognized marks of glaciation all over northern Europe"

2. the process of covering the earth with glaciers or masses of ice;

The Collaborative International Dictionary of English v.0.48:

Glaciation \Gla`ci*a"tion\, n.
   1. Act of freezing.
      [1913 Webster]

   2. That which is formed by freezing; ice.
      [1913 Webster]

   3. The process of glaciating, or the state of being
      glaciated; the production of glacial phenomena.
      [1913 Webster]

WordNet (r) 3.0 (2006):

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