Historical clue formulations

• Muscle ___, Ala. — 2021-12-08
• Nautical chart markings — 2019-07-18
• Sandbars — 2016-02-01
• Boating hazards — 2015-04-01
• Lighthouse locales — 2011-07-26
• Bars of a sort — 2008-11-20
• Schools of fish — 2002-10-30
• Lighthouse site, maybe — 1997-11-08