Hornocal: The Hill of 14 Colors

High in Argentina’s far northwest, beyond the colonial towns and cactus-studded valleys of Jujuy, rises one of South America’s most surreal landscapes: the Hornocal, or Serranía de Hornocal. Known as the Hill of 14 Colors, this jagged mountain range dazzles the eye with sweeping zigzags of red, green, purple, yellow, and white stone—like a colossal rainbow painted into the bones of the Andes.

Hornocal is not just a natural wonder. It is a living page of Earth’s geological history, a sacred place in Andean culture, and today, one of Argentina’s most breathtaking hidden treasures.

The Geology of a Painted Mountain

Hornocal’s breathtaking palette is the result of stratigraphy, tectonics, and mineralogy playing out over geological time. The serrated ridges belong to the Yacoraite Formation, a sedimentary sequence deposited during the Late Cretaceous Period (approx. 90 million years ago), when vast inland seas and river deltas covered this region of South America.

Over millions of years, layers of limestone, sandstone, marl, and shale accumulated, each stratum embedding the chemical fingerprint of the environment in which it formed. Later, during the Andean orogeny, the immense collision of the South American Plate with the subducting Nazca Plate subjected these horizontal strata to compressional forces, producing fold mountains with dramatic anticlines and synclines. Hornocal’s zigzag ridges are the exposed edges of these folded strata, revealed by erosional processes that stripped away softer material and left behind sharply defined, chevron-like patterns.

The vivid colors correspond to specific mineralogical compositions within the sedimentary layers:

• Hematite and goethite impart rich reds, pinks, and ochres through iron oxidation.
• Copper-bearing minerals (such as malachite traces) lend subtle greens.
• Calcium carbonate-rich limestone produces pale creams and yellows.
• Manganese oxides and volcanic ash layers contribute deep purples and bluish tones.
• Siliceous sandstones add neutral grays and whites.

This lithological diversity creates Hornocal’s signature multicolored bands, which are tilted at angles of up to 60°—a striking example of orogenic deformation. Geologists often describe the visual effect as a “natural chevron fold,” where the mountain face itself becomes a textbook illustration of tectonic dynamics and sedimentary history.

Hornocal in Andean Culture

For the Indigenous peoples of the Andes—such as the Quechua and Aymara communities—the mountains are more than geology; they are sacred beings, protectors of the land and sources of life. Known as apus, these high peaks were traditionally honored with offerings of coca leaves, food, or small ritual ceremonies.

Hornocal itself is part of the Quebrada de Humahuaca, a valley declared a UNESCO World Heritage Site in 2003 for both its natural splendor and its 10,000 years of human history. This valley was once a major route in the vast Andean trade networks, where caravans of llamas carried salt, maize, potatoes, and textiles between highlands and lowlands. Even today, local festivals blend Indigenous traditions with Catholic influences, echoing centuries of cultural layering.

One of the most vibrant festivals is the Carnaval de Humahuaca, held each February. Unlike the famous samba parades of Brazil, this Andean carnival is rooted in pre-Columbian celebrations of fertility and the agricultural cycle. The festival begins with the “desentierro del diablo” (unearthing of the devil), when a symbolic effigy is dug out from the ground to mark the start of revelry. For a week, the streets of Humahuaca erupt with music, dancing, masks, and flour-throwing battles, while locals drink chicha (fermented maize beer) and sing traditional coplas. At the end of the festival, the devil is “buried” again until the next year—symbolizing the return of order after chaos.

Another deeply rooted event is the Inti Raymi, the ancient Festival of the Sun, celebrated in June at the time of the winter solstice. Although more famous in Cusco, Peru, it is also observed in Jujuy. Communities make offerings of coca leaves, food, and alcohol to Pachamama (Mother Earth) and the mountain deities, thanking them for the harvest and asking for protection. Standing before Hornocal during Inti Raymi is a powerful reminder that the mountains themselves are sacred participants in these rituals.

Humahuaca also hosts the Fiesta de la Virgen de la Candelaria in February, blending Catholic devotion with Indigenous customs. Processions of saints weave through the town’s cobbled streets, accompanied by traditional Andean music and dancers dressed in vibrant costumes, some of which echo Inca-era traditions of honoring the natural world.

The Less Traveled Rainbow

Hornocal is often compared to Vinicunca, the Rainbow Mountain of Peru, but while Vinicunca has become crowded with mass tourism, Hornocal remains quieter, more remote, and—some argue—more spectacular. Its sheer scale, stretching in a vast serrated wall, gives it a grandeur unmatched by many similar formations.

Because of its altitude and relative inaccessibility, Hornocal still feels like a discovery.

Hornocal is more than a postcard view. It is a lesson in geology, a symbol of Andean culture, and a reminder of the unimaginable forces that shape our planet. The colors that captivate the eye are the fingerprints of deep time, preserved across millions of years.