The route runs through an interesting area of basalt cliffs, resulting from the cooling of lava flows emitted by different volcanoes, with some patches of riverbank woods with species of great botanical value.
Three lava flows (tres colades) from different volcanoes in the area descended in succession along this part of the Fluvià valley. The flows followed the course of the riverbeds and solidified. Later, the river deposited pebbles, sand and silt on top which were then trapped under the next lava flow.
During periods of heavy rain, if the Bianya stream has dried out, from Fontfreda, the route is not passable, so we must go back.
The recommended start of this route is at Ca l’Esquirolet, the Municipal Tourist Information Office of Sant Joan les Fonts, which is on Carrer Sant Pere, number 2, next to the mediaeval bridge. In front of Ca l’Esquirolet, next to the mediaeval bridge, we find the SJ12 crossroad and we continue in the direction indicated by the Tres Colades route signs towards the Fondo mill.
Here we can observe three lava flows, which were deposited one on top of the other at different times. The first, and also the oldest, is part of the artificial lock we will see at the Fondo mill. It is from the Batet volcanoes and is dated as approximately 600,000 years old. The second corresponds to the basaltic mosaic that covers this area. Its origin is unknown but can be dated at around 150,000 years old. The third, and most recent, corresponds to the Boscarró quarry, an outstanding place where one can observe the different shapes that the lava took as it cooled. It is from the Garrinada volcano, in Olot, and is dated as approximately 120,000 years old.
We go up the stairs and down the other side. On our right, we see some other stairs that allow us to descend to the Fondo mill lock, here we can see the Fondo mill waterfall and observe the recently discovered volcanic tube and blister caves.
Fondo mill is also the name given to the old paper mill that can be seen here, and which was the origin of the Torras Papel company.
We turn back and continue descending to Boscarró, where we find the sign for G16. We continue in the direction indicating the Boscarró viewing point and quarry. A few metres on, we find the SJ14 crossroad and we head towards the Boscarró viewing point and the Iberian village. Once at the top, we find a new SJ15 sign, we go to the right and from the viewing point, we can see the Fondo mill and interesting examples of industrial architecture at the river’s edge.
We go back and around the Iberian village, the volcanic rocks also hide a unique history, a society so ancient our eyes could not have seen it at first glance, a great esplanade where we can find archaeological remains that show the existence of an Iberian village that is unique in the La Garrotxa region and is exceptional within the province of Girona.
We cross the esplanade and at the end of the meadow we turn left following the yellow marks and head down to the Boscarró quarry.
At the Boscarró quarry, we can better observe the shapes formed by the lava when it cooled: During the cooling process the basalt forms different shapes; they are called retraction patterns: prismatic and lenticular. Prismatic (columns) occurs when the lava cools from the, already immobile, centre outwards. Lenticular (flat slabs) occurs when the still moving lava cools in parts.
On the other side of the quarry we see the SJ13 crossroad and go back to the G16crossroad. We return to the crossroad and head to the Fontfreda cliffs. The path leading us there is leafy and cool. The water and vegetation appear all along the path and the riverside wood appears in all its splendour. We particularly recommend it in the summer.
After a few minutes, we find a new crossroad SJ1 and continue towards the Fontfreda cliffs. After a few metres, we find a new crossroad SJ16 which is part of the Fonts i Verlets route. If we want to freshen up we can descend to the Can Xervanda fountain before climbing back up. We follow the yellow marks until reaching the Fontfreda cliffs.
The cliff and all the surrounding area was cleaned and restored in 1993. It is a good place to see more details of the solidified lava flow. The dimensions of the cliff are spectacular here. It is just here where we need to cross the Bianya river over some stone walkways and where, during periods of heavy rain, it is necessary to turn back.
We cross the stream and a few metres further up, we must cross it again to continue the route. We arrive at the SJ17 crossroad and head towards Sant Joan les Fonts for the La Canya volcano. At the SJ18crossroad, on the Les Mulleres path, we head to Fontfreda; this section also coincides with part of the Fonts i Verlets route. A few metres on, we find the SJ4 crossroad and head to Fontfreda. After a few metres, we pass by Fontfreda and continue to the SJ9 crossroad where we now head to La Rompuda fountain.
On Carrer de mas Marunys, we find the SJ8, SJ2 and SJ10 crossroads, we head towards Sant Joan les Fonts until we reach the starting point of the route.