Quebrada de Humahuaca: Argentina's Rainbow Valley
Hornocal Hill | © Klaus Balzano / Shutterstock


The mountain valley of Quebrada de Humahuaca, in the province of Jujuy, in north-west Argentina, is home to some fascinating geology. The incredible colors and the inverted-V shaped formation seen here is part of the limestone formation called Yacoraite that extends from Peru to Salta, through Bolivia and the Quebrada de Humahuaca.

The Hill of Seven Colors and Painter's Palette in Maimará are famous, but most visitors leave the creek without knowing the mountains of Hornocal or “Serranias del Hornocal”.

The Serranía de Hornocal are a range of mountains located 25 kilometers from the city of Humahuaca in the Argentine province of Jujuy. Exposed in the range is the limestone formation called Yacoraite that extends from Salta, Argentina, through the Argentine Quebrada de Humahuaca and then through the Bolivian Altiplano to Peru, The Yacoraite Formation is a largely Mesozoic geologic formation.



The deposits of this formation mainly date from the Maastrichtian of the Upper Cretaceous, but the Cretaceous–Paleogene boundary (K–T boundary) runs right through this formation near its top, and the uppermost parts are consequently from the Danian (Lower Paleocene). It was probably deposited around the intertidal zone, as the sedimentary rocks of this formation alternate according to sea level changes between deposits of muddy beaches and of shallow ocean.

Serranía del Hornocal is a best example of the Flatirons, this landform is small knolls with a triangular to trapezoidal-shaped sloping surface with the long side of this surface as their base and a point at their top. It was created by the differential erosion of a steeply dipping, erosion-resistant layer of rock overlying softer strata. Flatirons have wide bases that form the base of a steep, triangular facet that narrows upward into a point at its summit. The dissection of a hogback by regularly spaced streams often resulted in the formation.

Photo: © Bookmundi.com
Quebrada-de-Humahuaca. Photo by Ossian Lindholm

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