Historical clue formulations

• What can fall off a shelf — 2020-08-02
• A little one is called a calf — 2018-07-27
• Big chip off the old block? — 2009-07-30
• Kind of lettuce — 2008-07-30
• Hard-to-get-to-know person, so to speak — 2003-07-26
• Renewable freshwater resource — 2002-09-28
• Shipping hazard — 2001-09-20
• Big chunk of the Atlantic? — 2001-06-23
• Ross Sea sight — 1999-12-24
• Cruise ship sighting — 1996-03-16
• Emotionally cold person, informally — 1995-06-23
• Arctic sight — 1995-02-03
• Ship's peril — 1995-01-20