Following the Würm glaciation (around 80,000 to 10,000 BC), the Cleurie valley was blocked. The water from the Hohneck massif accumulated to form Gérardmer's lake. The overflowing waters of the lake had no other possibility than to rush into a small river, the Jamagne, which joins the Vologne. On its banks is a volatile plant called beggars-grass. Its name originates from the beggars of the Middle Ages who noticed the skin ulcers it caused. They rubbed their faces with it before begging outside churches, then cured themselves by applying chard leaves on the wounds.