Access by:

- N339, km 28-29.

Here is one of the largest and most perfect glacier circuses of Estrela mountain, traces of glaciations that occurred in Pleistocenic (35,000 to 20,000 years BC). Cântaro Magro is a granitic outcrop with 1928 m of altitude, whose relief is the result of differential erosion (the rocks around it were eroded and disappeared leaving this great rock). Probably, during glaciations, the ‘Cântaro Magro’ was a nunatak that have been uncovered and without the ice of the glacier. On the southern slope of the base, a rock vein, similar to basalt and less resistant to erosion than granite, was being eroded, creating in its place, a gap between large rocks known as “Rua dos Mercadores” (Merchants Street).

Cirque glacier - amphitheatre-shaped basin with steep walls, formed on a mountainside by glacial erosion.

Nunatak - a mountain peak or ridge that pokes through the surface of an ice field or a glacier.