When glaciers retreat during warmer periods, they leave behind ridges of sediment.
Notes on verification
Well-established glacial geology confirmed by multiple independent academic and educational sources (LibreTexts, Britannica, AntarcticGlaciers.org), consistent with scientific consensus on moraine formation. [cascade flags: aggregator_dropped_primary_exists | tier=bronze indep_score=0.3 clusters=2 claim_tier=everyday]
Sources
- Ice Age - Definition & Timeline (seed:history_and_archaeology)
- https://geo.libretexts.org/Courses/University_of_California_Davis/GEL_109:_Sediments_and_Strata_(Sumner)/Textbook_Construction/Glacier_Deposits (corroboration)
- https://www.antarcticglaciers.org/glacial-geology/glacial-landforms/glacial-depositional-landforms/moraine-types/ (corroboration)