During the height of the Würm glaciation a glacier, 1,000 km2 in area, covered the Black Forest. As a result, a lot of glacial influence can be seen in the region. There are several features that relate to the glacial morphology of the Feldberg. Firstly, there is the Feldsee. This tarn formed in the hollow that was scoured out by the ice pushing down the headwall of the cirque. Gradually the ice created a bowl that now holds the 33-metre-deep Feldsee. A moraine on the shores of the Feldsee testifies to this process.