Hiking the Amazon Jungle & Thinking About Erosion

Hi everyone,

It's been a while since my last post since I am currently on vacation! In the French school system, there is a two week vacation after every ten weeks of instruction. (It's great.) 

I recently went on a camping trip with other teachers in the Amazon jungle, at Le Sentier Savane Roche Virginie, which roughly translates to the Virgin Savannah Rock Hike. (This will make sense in a few pictures.) It's about a two-hour drive from where I'm currently staying.

Location of Le Sentier Savane Roche Virginie. The blue dot is where I am staying in the town of Matoury. (Oct 2016) (Courtesy: Google Maps)

I started camping and hiking in a serious manner when I was in high school, and at age 17 I did my first solo-camping trip for five days and four nights in the White Mountains of New Hampshire. My love of the outdoors is a big reason why I decided to become a geologist. As a geologist, it feels amazing and empowering to be outside and understand what is going on around you. 

High school Renée climbing the roots of an overturned tree. (Dec. 2011) (Courtesy: author)

But, back to the present - this was my first time hiking and camping in the Amazon Jungle, and boy it was hot. I don't think I've ever sweated so much during an hour-long hike before. The jungle floor is shaded and dark because all the plants are competing for every inch of sunlight they can get, but it's not much cooler in the shade. In fact, the heat and the humidity almost seem worse because you can't catch any passing winds.

Waiting to cross a small bridge during the hike (Oct. 2016) (Courtesy: author)

But, there are all sorts of fascinating plants and animals to be found on the forest floor! Small pigs, pecarries, live in burrows and you can occasionally hear them sprinting away from you as you startle them along your path. Monkeys can be heard screeching as they swing from tree to tree. Cicadas give off their incessant, high-pitch whine. There are also plants of every kind - trees, mushrooms, ferns - and occasionally, rocks! 

Large, allochthonous boulders can be seen as you near the top of mountain. Allochthonous just means that these rocks originated elsewhere before being moved by erosional forces (wind, water, ice, mud, etc.) to their current positions. Allochthonous boulders are normally indicative of incredible erosional forces - think of how much energy it takes to move that much mass! These rocks were granite, meaning that they crystallized slowly beneath the Earth's surface. And unlike the granite I've seen before, these rocks were weathered to the point where they were almost black. I almost mistook them for basalt at first, the rock type that Hawai'i is mainly composed of.

Sorry for the blurry photo! Next to a giant boulder. (Oct. 2016) (Courtesy: author)

This extensive weathering becomes very clear once you reach the top of the mountain. There, plants have not yet been able to establish themselves on the rocks, so the expanse is bare and weathered. Because of this, it offers one of the best viewpoints for surveying the surrounding Amazon jungle, and this is likely why this spot was turned into a tourist attraction.

Heavily weathered granite. Women's size 8 shoe for scale. (Oct. 2016) (Courtesy: author)

In addition, the shapes that the weathered rocks had taken on (their "geomorphology") were some of the wildest I have ever seen. It looked like lumpy waves of rocks cresting through the top of the Amazon jungle.

Look at the incredible effects of erosion! (Oct. 2016) (Courtesy: author)

Another view of the rocks. (Oct. 2016) (Courtesy: author)

It reminded me of a Shel Silverstein poem about this guy who found out he has a wavy head instead of wavy hair. Walking up the mountain and peeling back the cover of the Amazon jungle revealed the fascinating, geologic surface that all these plants have grown on. It was a humbling reminder that before all these plants were here, this place was once barren rock. (These are the virgin rocks this place was named after!) But thanks to the work of tiny microbes eating away at the rock to create soil, climatic conditions, and the tenacity of plant life, here now exists the world's largest tropical rainforest.

"Wavy Hair" by Shel Silverstein.

But in addition to all the wonderful geology I saw, I also was able to share good fire-side meal with new friends & explore more of the wonders that French Guiana has to offer. Even if the rocks weren't there, my trip would have been worth it for that!

A view from the top of the mountain. (Oct. 2016) (Courtesy: author)

Thanks for reading, and until next time!

​Renée