A Strange Sound                                        -      N      - 
(-------------------------------------------------)     W <---(M)---> E
                                                        -      S      -

You hear a massive rumble from up above.  You wonder what it could be. 
Perhaps you should make haste into another area to the south of here,
whatever is occuring up in that mountain side can not be good for you.  To
the north of here is a small alcove, very difficult to enter and probably
nearly impossible to leave quickly.  To your south you hear the stream rush
merrily by.