The Collaborative International Dictionary of English v.0.48:

Wealden \Weald"en\ (?; 277), a. [AS. weald, wald, a forest, a
   wood. So called because this formation occurs in the wealds,
   or woods, of Kent and Sussex. See Weald.] (Geol.)
   Of or pertaining to the lowest division of the Cretaceous
   formation in England and on the Continent, which overlies the
   Oolitic series.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Wealden \Weald"en\, n. (Geol.)
   The Wealden group or strata.
   [1913 Webster]