The glacial valleys of the Serra da Estrela are unique in Portugal and are witness to the glacial era.

The glaciation (which occurred 20,000 years) led to the existence of perpetual snow that melted and made compact. He graduated so an icy summit at the Presidential Tower, this would have an area of 70 km2 and 80 m thick.

These valleys have originated in the passage of ice languages that have shaped through its strength to escoarem from the cone tower. These tongues of ice formed due to a progressive increase of temperature, although always negative.

There are five routes outlined by ice:

- Zêzere Glacier Valley, the largest in Europe;

- Alforfa Glacier Valley;

- Loriga Glacier Valley Glacier;

- Valley Covão Grande;

- Valley Covão Urso(Bear) Glacier.