Historical clue formulations

• Rocks out? — 2023-01-20
• Rocky outcroppings — 2022-06-07
• Rocky outcrops — 2022-03-29
• Parts of bluffs — 2019-06-16
• Rock-climbing challenges — 2012-09-30
• Rugged rocks — 2011-11-09
• Rugged rocks — 2001-09-03
• Rough projections — 2000-02-20
• Cliff sights — 1997-09-11
• Mountain-climbing challenges — 1996-07-28