The Collaborative International Dictionary of English v.0.48:

Interval \In"ter*val\, Intervale \In"ter*vale\, n.
   A tract of low ground between hills, or along the banks of a
   stream, usually alluvial land, enriched by the overflowings
   of the river, or by fertilizing deposits of earth from the
   adjacent hills. Cf. Bottom, n., 7. [Local, U. S.]
   [1913 Webster]

         The woody intervale just beyond the marshy land. --The
                                                  Century.
   [1913 Webster]