Historical clue formulations

• Glacial ice formation — 2006-09-10
• Polar irregularity — 1999-01-16
• Glacial ice formation — 1997-04-06
• Glacial pinnacle — 1995-10-05
• Glacial peak — 1995-03-19
• Icy pinnacle — 1994-10-28
• Glacial ridge — 1994-04-24