Lac noir et Lac Blanc

After the retreat and melting of glaciers, moraines form natural dams in the valleys. Behind them, waters accumulate. They give birth to lakes like those of Gérardmer and Longemer. Cirques abandoned by glaciers will also be occupied by lakes, like Lac Blanc and Lac Noir, or invaded by peat bogs. Where bedrock outcrops, the alternation of freezing and thawing causes the widening of fissures, loosening of blocks and their collapse. This phenomenon is the origin of the rock chaos so frequent on the Vosges slopes.

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