Inland Atlantic-Mediterranean transitional territories in the Valderejo Natural Park (Araba, Basque Country). We will visit a varied set of plant communities following a climatic gradient from Atlantic to Mediterranean. The treck starts in the village of Lalastra and stretches about 7 km following a downward trial along the Purón river, saving a rump of 300 m. We will have the opportunity to see beech (Fagus sylvatica), Quercus faginea and Quercus rotundifolia forests, as well as Genista occidentalis scrub and Festuca hystrix hard grasslands. Along the last stretch of the trial, we will walk along a canyon and have the possibility to see impressive calcareous cliffs. The treck ends in the village of Herrán, where the bus will be waiting for us. If there is time, we will have a short visit to the medieval town of Frías, where we will have the possibility to have a coffee.

The difficulty is medium to low but we will have to walk most of the day.

Leader: Javier Loidi.