The Collaborative International Dictionary of English v.0.48:

Basset \Bas"set\, v. i. [imp. & p. p. Basseted; p. pr. & vb.
   n. Basseting.] (Geol.)
   To incline upward so as to appear at the surface; to crop
   out; as, a vein of coal bassets.
   [1913 Webster]