TREELINE
| Date | Clue |
|---|---|
| 2016-07-09 | Certain upper-growth limit |
| 2009-08-02 | Timberland limit |
| 2005-12-16 | Fringe of the green? |
| 2004-11-20 | Mountain demarcation |
| 2003-12-06 | Tundra borderer |
| 2000-03-25 | The edge of the green? |
| 1999-09-11 | Where the top begins to get bare |
| 1999-04-30 | It's about 2,500 feet up on Mt. McKinley |