Underneath the story of the paintings is a story of rock. The Sierra de Guara is made largely of limestone and sandstone laid down in warm seas tens of millions of years ago, then pushed up as the Pyrenees rose to the north, and then cut by rivers into the gorges you see today. The Vero has carved a deep canyon through the layers, and where softer bands of rock have weathered away, they have left overhangs, shallow caves and ledges that were perfect for shelter. Gallinero II, five kilometres from Alquézar, is one of those natural shelters, and it holds prehistoric paintings, part of the Mediterranean Basin rock art that UNESCO listed in 1998.
Geology also explains the colours. The cliffs here are pale grey where the limestone is fresh and orange or ochre where iron has stained the surface, and in the right light the whole valley glows. The red tones used by the painters were probably made from iron-rich earth, which was ground and mixed with a binder, and which is part of the reason the paintings have lasted so long under their overhangs.
The Sierra de Guara is also fossil country, and in some places on the hillsides you can find the shells of marine creatures from the ancient sea. It is a quiet and bare country in places, with scrub oak, box and juniper, and in winter the grey rock and the dark green trees have a stern beauty. Spring brings wildflowers, orchids among them, and the first greens.
Riding here is enjoyable at a moderate pace. The roads follow the contours of the land, and bends are frequent and not always well signed, with gravel in the gutters and the odd rock on the road after storms. On the main road from Barbastro the surface is generally good. The nearest place for fuel and shops is Barbastro, about twenty kilometres from the village, a town of some seventeen thousand people with plenty of restaurants.
Bring water and sturdy footwear if you plan to walk, and follow local guidance on access, since the shelters are fragile and some are protected by law.