The Collaborative International Dictionary of English v.0.48:

Terrane \Ter"rane\, n. [F. terrain, from L. terra earth.]
   1. (Geol.) A group of rocks having a common age or origin; --
      nearly equivalent to formation, but used somewhat less
      comprehensively.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Terrane \Ter"rane\, n. (Geog.)
   2. A region or limited area considered with reference to some
      special feature; as, the terrane of a river, that is, its
      drainage basin.
      [Webster 1913 Suppl.]