Climate, culture and history of the Quebrada de Humahuaca

Because the Quebrada de Humahuaca is such a long north-south valley with readily available water from the river (Rio Grande) that cut it, it has been a well-used route connecting Peru, Bolivia and Argentina for thousands of years. The region was also important in the revolution for independence from Spain (1810).

To the west, the highest part of the Andes, called the Puna in Argentina and the Altiplano in Bolivia, is a moonscape where few people live. To the east, there are more mountains and the forests of Brazil and northeastern Argentina that capture most of the water being delivered by the westward-flowing trade winds. The Quebrada and Puna are quite dry, but still not as dry as the Atacama Desert on the western side of the Andes (in Chile) that gets almost no precipitation because of the strong rain shadow effect.


Cerro Miniques (above) is a volcano in Chile that is very close to the Argentina border. [This photo was taken in 2006 when we visited San Pedro de Atacama and the Atacama Desert while I was a Fulbright Scholar in Chile.] This volcano has an elevation of 5900 meters (19,300 feet); there are many equally-high, active volcanoes that extend north–south along the Chile/Argentian border. A little moisture gets to these highest elevations but almost none reaches the lower elevations of the Atacama Desert to the west.

The Quebrada of Humahuaca is located in the sub-tropics. It is easy to remember the latitude because the Tropic of Capricorn (23 degrees south) passes through the Quebrada.


Here we are (view to the west) at the marker between the towns of Tilcara (to the south) and Uquía (to the north).

Although this trip is mostly in the part of the Andes that is east of the Puna (Cordillera Oriental), we were fortunate to find an excellent guide—Victor Cuezzo (www.equipatuaventura.com.ar)—who drove us over a mind-bending pass to the Salina Grande in the Puna. The Puna has many salinas because of the closed, internally-drained valleys located between the mountains to the east and the volcanoes along the crest of the Andes to the west.

People have been using the salt in the salinas and trading it for other goods for thousands of years. At this location on the salina’s edge, we could see how the local community benefited by cutting the salt into blocks, putting the blocks into large bags, and selling it to others. The people were using the salt creatively, to make statues, and practically, to make buildings and souvenirs for tourists. Lithium is also found in some of the salinas but the local people are not in favor of this because the benefits go mainly to large international companies.

When we went trekking with the llamas, we had the good fortune of visiting Adela’s mother who lives even higher in the valley than her father. They get together sometimes, but Adela’s mother (at age 70) is fully occupied caring for a herd of about 150 goats and making artisanal cheese from their milk. The methods she is using go back many generations.


Adela’s mother with a large pail of goat milk and the starter she uses to make delicious, completely hand-made cheese. Although this method would never pass health codes in the United States, she takes great care to keep the cheese sanitary and sells the cheese in town (Tilcara).

To get salt for the cheese, she grinds salt from a block, probably derived from Salina Grande, using a flat rock for the mortar and a round rock for the pestal.

Although Adela now lives in Tilcara, and lived most of her adult life in Buenos Aires, she grew up in these mountains until the age of 16. From her grandmother she learned uses for many of the local plants, and even learned which rocks are best used for tasks such as cooking or making ceramics.


Here is Adela with the youngest member of the goat herd, who had to stay back while the adults went out to graze on pasture and the juveniles got fed alfalfa. We marveled at the fortitude of Adela’s mother, who works so hard every day to care for her goat herd, about 6 dogs, and some cats and chickens. Yet she seemed very happy with her life.

Victor also drove us to the remote town of Iruya, located east of the Quebrada and only accessed by a harrowingly narrow, winding road. The youthfulness of the landscape is in full view here—nearly vertical slopes and an extremely narrow valley formed by deep incision of the river—a clear indication that the land is rising now at a rapid rate. The eroded cliff on the left side of the photo consists of young alluvial fan deposits (some thousands of years old) with huge boulders that hover over the road. I would not want to be there in the rainy months when large boulders certainly fall onto the road and the sediments, mostly debris-flow deposits, get recycled again into debris flows that are potentially very dangerous.

People in Iruya still retain many of their ancient traditions, which they have melded with the cultures imposed on them by the Spaniards. At the yellow church, people were preparing for a peregrinación (walking pilgrimage) to Salta located 317 km (almost 200 miles) away.

There are a vast number of archeological sites in the Quebrada de Humahuaca and in the surrounding landscape. People first arrived here about 10,000 years ago and the area appears to have been continually occupied since then. Most of the history is pre-Inca, as the Incas had only expanded their empire to include this area a short time before the Spanish arrived (yet another conquerer).


Victor took us to a site with a large number of petroglyphs with a variety of ages. Some were formed in the past 600 years because they show the conquistadores on horseback. Others were much older. This petroglyph has llamas and ostrich-like birds called ñanus.

This region of Argentina is unlike any other in this country. Many traditional foods, music, and other cultural traditions are still followed. In many ways, it feels more like being in Peru or Bolivia than in Argentina.


This dish, called locro, consists of meat (often llama) with some combination of vegetables, legumes, and potatoes. As the place of origin for potatoes, there are many different varieties, most much smaller than the typical “Idaho potato”. Quínoa is also used in many dishes.

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La Quebrada de Humahuaca—colorful landscape in NW Argentina

A quebrada is a valley or canyon formed by the action of flowing water. The Quebrada de Humahuaca is located in the northwesternmost corner of Argentina, on the eastern side of the Andes, where active uplift of the land has caused rivers to cut down and create quebradas of many sizes and shapes, resulting in a stunning landscapes of shear cliffs and massive incisions. 


This view to the west is down an east–west-oriented tributary quebrada near the town of Tilcara that feeds into the much larger Quebrada de Humahuaca that extends north–south. We went trekking with llamas (www.caravanadellamas.com), who carried our gear. My llama was named Puca, which is the indigenous word for reddish color.

The Quebrada de Humahuaca is an attraction for tourists because of its brightly colored rocks, which have been exposed as the Andes have been uplifted and rivers have cut down to expose rocks that range in age from Precambrian to very recent. The older rocks that have been somewhat metamorphosed generally have dark colors of greens and greys. In contrast, there are white and light grey limestones that formed from a variety of organisms in shallow marine environments. But what most catches the eye are the reds, oranges, purples and yellows of sedimentary rocks that were deposited in continental environments such as rivers, where exposure to the atmosphere caused iron in the sediment to oxidize (to rust!).


Pumamarca is a small town in the quebrada that is popular for its Cerro de Siete Colores (hill of seven colors). Of course, the number of colors is highly subjective!

On our three-day trip with the llamas , we were able to trek into the mountains east of Tilcara, to a much higher valley that is oriented parallel to the Quebrada de Humahuaca, which at Tilcara is at an elevation of 2500 meters (about 8000 feet). The scale of this vast landscape is impossible to capture in a photo.


Here are Jay and Adela, our guide, in the high valley near the house of Adela’s father, where we stayed over night. His house is located at about 3100 meters (10,000 feet). There are no roads and at an age of 78 her father lives without electricity or running water and must walk or ride his burro to town for supplies. 

These north–south valleys are all formed from east–west-oriented compression and are a series of folds (imagine pushing on a rug until it is folded into hills and valleys). We trekked around the high valley that is a large-scale syncline; that is, layers are inclined toward the center of the valley, although there are many complications to this overall structure.

 

We were able to see many small-scale features such as this syncline. Cactus for scale is about 2 meters (6.5 feet) high. The larger-scale features are more easily seen from the air or using Google Earth. 

A popular place to visit is the Serrania de Hornacal, located east of the town of Humahuaca. People go to the Mirador de 14 Colores (viewpoint of 14 colors) to see colors best displayed before the sun is getting ready to set. You can imagine that many photographers come to this part of the world and take great pains to be in the right place for the perfect exposure of colors in the early morning or late afternoon light.


This photo of the Serrania de Hornacal was taken in the late afternoon, but unfortunately rare spring clouds appeared to obscure the sun just before we arrived at the mirador. Nevertheless, it was a thrilling sight, especially because for geologists this is one of the finest possible examples of flat irons in the landscape. Flat irons are formed when layers (usually sedimentary) are inclined steeply and then eroded into shapes that look like the bottom of the tool used to iron clothes. The colors are a result of the different sedimentary layers that are exposed by erosion when water flows down the slope.


But only when I looked at Google Earth did I realize this cliff of tilted sedimentary layers is part of a large-scale plunging synclinal fold. All of the layers are tilted toward the center of the fold (we were viewing the north limb); in contrast, in anticlines all of the layers are tiled away from the center.

The reason for all of these folds will be explored in a future post.