Serranía de Hornocal

The Serranía de Hornocal is a mountain range in the far north-west of Argentina whose slopes are folded into rows of sharp triangles, each striped in a different colour. Seen from the viewpoint opposite, at around 4,350 metres, the ridge looks like a giant zigzag pattern of ochre, yellow, rust red, pink, violet, white and green, repeated along the hillside as if woven. Locals call it the Cerro de los 14 Colores, the hill of fourteen colours, and while nobody needs to count, the name catches the sense of a whole palette laid side by side. The summits of the range reach about 4,760 metres.

The colours come from the rock itself. The range exposes the Yacoraite Formation, a sequence of limestones and sandstones laid down along muddy shores and in shallow seas at the very end of the Cretaceous, about 66 million years ago; the boundary between the age of dinosaurs and the age that followed runs through its upper layers. Across the region the same beds preserve dinosaur footprints, fossil eggs and stromatolites. Later, when the Andes rose, the strata were tilted and folded, and erosion carved them into the serrated pattern that now stands on end against the sky.

The Hornocal belongs to the wider landscape of the Quebrada de Humahuaca, a long valley in Jujuy Province declared a World Heritage site in 2003 for its coloured mountains and for the ancient routes, including Inca caravan trails, that ran through it. Reaching it means a long climb by gravel road onto the high ground above the valley. The colours are strongest in the afternoon, when the sun falls fully on the face of the range; the altitude is high enough to be felt, so it pays to move slowly.

Getting there

The Hornocal lies about 25 km from Humahuaca, the nearest town, along the gravel Provincial Route 73, which winds up to the viewpoint. The nearest airport is Gobernador Horacio Guzmán International Airport (JUJ) near San Salvador de Jujuy, roughly 125 km away in a straight line; from there the road runs north up the Quebrada de Humahuaca to the town.