Equilibrium line/zone
The line or zone on a glacier’s surface where a year’s ablation balances a year’s accumulation (cf. Firn line). It is determined at the end of the ablation season, and commonly occurs at the boundary between superimposed ice (q.v.) and glacier ice.
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The arrow in this photo actually points out the firn line. However, as the photo was taken near the end of the ablation season, the firn line more-or-less coincides with the equilibrium line. Aerial photo J. Alean. |