Historical clue formulations

• Stone memorial — 2021-07-18
• Shaggy Scottish dog — 2016-08-06
• Pile of stones used to mark a trail — 2015-12-27
• ___ terrier (dog breed) — 2014-04-28
• Terrier type — 2012-08-08
• Stone heap — 2009-04-05
• ___ terrier — 2008-12-25
• Stone heap — 2006-10-29
• Rock landmark — 2005-07-21
• Stone memorial — 2005-01-23
• Monumental stone heap — 2003-10-10
• ___ terrier — 2003-10-05
• ___ terrier — 2001-09-30
• Stone landmark — 2000-06-04
• Kind of terrier — 1998-12-06
• Stone mound — 1997-08-18
• Stone landmark — 1995-12-24
• Stone marker — 1995-09-14
• Stone heap — 1994-08-07