The Madriu-Perafita-Claror Valley is of glacial origin with geomorphological interest throughout almost its entire extension.

The relief of this area, which is very uneven, sits on a substratum of siliceous rock (granitic at Gargantillar-l’Illa and metamorphic at Port Negre), on which the modelling action of the firns has worked. The U-shape of the valley, the cirque glaciers, the rocky firns, the hanging valley of L’Estany Blau, the plateaus of the Camp de Claror or the dynamics of the avalanches are clear examples of the glacial origin of the valley. There is also a large number of mountain peaks where the peak of La Portelleta stands out, at 2,905m, the highest in the protected area.

In the Camp de Claror, the interest lies in the fact that it has models similar to subpolar latitudes and tundra regions (Spitzberg). They are geometrical figures (polygons and circles of stones), which are exceptional and rare testimonies of high scientific value in the Western Pyrenees.