The Collaborative International Dictionary of English v.0.48:

Queachy \Queach"y\, a.
   1. Yielding or trembling under the feet, as moist or boggy
      ground; shaking; moving. "The queachy fens." "Godwin's
      queachy sands." --Drayton.
      [1913 Webster]

   2. Like a queach; thick; bushy. [Obs.] --Cockeram.
      [1913 Webster]