Chile Con Karen: San Pedro de Atacama's Valle Arcoiris

The most "colorful" section of the Valle Arcoiris we saw.

The small town of San Pedro de Atacama is the gateway to a particularly striking section of the Atacama Desert. (The entire desert covers much of northern Chile and southern Peru.) All year, hundreds of tourists set up base camp in San Pedro de Atacama, filling its hotels and hostels, and piling into vans every morning and afternoon to tour one part or another of the unique surrounding landscape. We recently visited San Pedro, and our first destination was the famous Valle Arcoiris (rainbow valley).

Valle Arcoiris

We were treated to an enthusiastic but hard-to-follow explanation by our guide of how exactly the Valle Arcoiris formed, with hastily drawn visual aids in the dirt. The gist of it is that there is a lot of geological and volcanic activity in the area. Pressure and heat far beneath the earth's crust create brightly colored minerals and crystals, and rapidly-cooling molten lava forms strange and striking rock formations. And while most of the valleys, plains, and mountains of the San Pedro region are covered in volcanic ash and dust, the Valle Arcoiris is particularly old and has been "washed" over the centuries, revealing the rock pillars and colors beneath.

A short hike up among the green and purple rocks brought us to the remains of an ancient building- at this point it's not much more than low walls made of stacked stones. The age can be calculated by measuring chemicals that form on the surfaces of rocks when they are exposed to the sun's radiation. If the top rocks have levels that correspond to millions of years, and the bottom rocks have levels that correspond to three thousand years less, then the structure is probably approximately three thousand years old... or something like that.

There was a surprisingly large amount of greenery when we visited- apparently this is the short-lived effect of Winter rains. Our guides told us most plants die within a couple weeks and only sprout again after the next rain.

Not far from the more colorful regions of the valley there is a large cluster of rocks sticking up out of an otherwise flat plain- the Hierbas Buenas Petroglyphs site. These rocks have petroglyphs - rock carvings - that are thousands of years old. There are also some that are significantly younger, from before the area was declared a national heritage site and placed under governmental protection. But hey, someday even the new carvings will be thousands of years old too. The trick to estimating the age of the carvings is knowing that the rocks (since they are essentially compressed volcanic ash) are white inside, but turn red when exposed to the sun. A carving that is still white is young; a carving that is red, but less red than the surrounding rock, is old; and a carving that appears the same color as the surrounding rock is VERY old.

Karen pointing at Petroglyphs

Many of the carvings depict guanacos, or their domesticated counterparts, llamas. This is unsurprising, as even while we were there, a pack of llamas wandered through, as they have been doing for a very long time. According to our guide, most of the petroglyphs here defy categorization, since they do not correspond clearly to any particular 'age' or 'school' of ancient stone art. It's also important to bear in mind that the artist might have been practicing, or just plain untalented.

Some notable petroglyphs: an enigmatic two-headed guanaco, which may simply be a guanaco giving birth; a pregnant fox depicted as a large fox with another smaller fox inside it; and a MONKEY (monkeys don't live here- but I suppose there was trading with groups as far away as the Amazon). Although the site is somewhat controlled (there is a path with arrows, and a small booth with a park ranger who sells entrance tickets), people are allowed to clamber over the rocks however they want and there is almost no supervision. We did not touch the carvings since that would probably damage them- but you definitely could if you wanted to!