An Earthy Room                                         NW     N      - 
(-------------------------------------------------)     W <---(M)---> -
                                                        -      -      -

Although the igneous rock walls of this cavern make it quite obvious that
the chamber was formed by volcanic activity, the floor is covered with a
think layer of soil.  While you are busy wondering how so much dirt has
collected here, you notice that there are several large mounds coming up out
of the ground.