The Gralles cave

A very clear example of regression of a river valley by erosion

It is a great cave at the back of the canyon of the Nova Fountain, near the source of the Llúdriga. It is a perfect geological example of when the valley actually gets wider further down, due to erosion from water and ice. 
You can get to it from the road from Capafonts to Alcover. From the first left bend, there’s a track to the right. There is a sign indicating the path towards La Mussara.
The cave has an impressive dome shape, and is about 15m deep, with a drop of about 60m. After rain the stream turns into a waterfall that looks like a beautiful ponytail can be seen from various places in the area. Throughout the year the stream flows, even if a mere trickle. At its foot, rough rocks frame a small beach and a pool, that is always full of water.