The Collaborative International Dictionary of English v.0.48:

Geologize \Ge*ol"o*gize\, v. i. [imp. & p. p. Geologized; p.
   pr. & vb. n. Geologizing.]
   To study geology or make geological investigations in the
   field; to discourse as a geologist.
   [1913 Webster]

         During midsummer geologized a little in Shropshire.
                                                  --Darwin.
   [1913 Webster]