In the time of middle earth, the puzzle was not at the posted coordinates so don't go there.
BUT....
In order to solve where the one true ring, er, geocache is, you'll need to view the beacon and obtain some information from the lower left side as viewed from the south. It is possible to view said beacon legally and without trespassing, so I suggest doing that.
North - 45 (first digit)(second digit plus four) point (second digit plus one)(first digit plus two)(third digit minus two)
West - 093 (first digit plus one)(last digit) point (last digit plus one) (third digit minus one)(first digit)
This is easy enough to do without a checker if you find the proper beacon.
!ABSOLUTELY NO STOPPING ON HIGHWAY 10! Be observant of any park hours if listed. Seek at your own risk.
Please re-cover as well as possible so it doesn't go missing.