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Severe Erosion Reveals Earth’s Treasures

Glancing down into a tourmaline mine in a lavaka. Photo: Alizé Carrère
Glancing down into a tourmaline mine in a lavaka. Photo: Alizé Carrère

National Geographic Young Explorer Alizé Carrère is researching an innovative method of agricultural adaptation in the Malagasy highlands that has emerged in the face of severe deforestation. Known to locals as “lavaka”, literally meaning “hole”, they are massive erosional gullies that provide surprising agricultural and socio-economic benefits, turning a deforested landscape into one of opportunity, not hardship.

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When I began my research on lavaka back in October, my first blog post was titled, “Scarred Hillsides in Madagascar May Actually Be Agricultural Gold Mines”. While my fieldwork has proved this to be true in many cases over the last three months of my research, what I didn’t know was that lavaka can, in some instances, be literal gold (and other precious and semi-precious stone) mines.

I first heard about this when my field assistant told me that just a few months before I arrived, a headline was made in Madagascar about a farmer who discovered a very large precious stone when a lavaka formed on his land and revealed its hiding place. It was supposedly bought by a man from China for a very hefty price.

I didn’t give the story much more thought after that, until I was on another field excursion in the central part of Madagascar’s highlands. We were being led by a farmer who had several lavaka on his land, trekking up the hillside and into one of these giant erosional depressions. We worked our way across the lavaka’s rugged interior while he answered my many questions about how it formed, what he’s planning on doing about it, and if he sees any advantages to having it on his lands.

Walking through the upper left half of the lavaka. This lavaka was particularly unusual as the displacement of soil revealed an extensive layer of bed rock, making stabilization efforts through the planting of trees and vegetation near impossible. Photo: Alizé Carrère
Walking through the upper left half of the lavaka. This lavaka was particularly unusual as the displacement of soil revealed an extensive layer of bed rock, making stabilization efforts through the planting of trees and vegetation near impossible. Photo: Alizé Carrère

About half way across we encountered what I thought was a very deep well. It was a perfectly maintained hole roughly a meter in diameter, almost too perfect-looking in comparison to the rest of the lavaka’s rough façade. We started walking past it, until I suddenly realized that this would be an extremely odd place for a well. I stopped and hollered up front to the farmer asking what this hole was about.

He swiftly turned around and said, “Oh, it’s a tourmaline mine”. He said it with such nonchalance that it genuinely surprised me. Although tourmaline is only a semi-precious stone, it is still something that would fetch extraordinarily high prices in comparison to what this humble farmer is typically accustomed to making from his crop harvests.

Seeing my intrigue, he walked back to meet me as I peered down the hole. It was so deep that I couldn’t see the bottom, and there were foot holes going down either side of the interior where the miner would brace himself as he followed the trail of the deposit downwards. I saw the thin straight line of the tourmaline deposit, collections of light grey stones stretching down into the darkness.

The tourmaline deposit. Photo: Alizé Carrère
The tourmaline deposit. Photo: Alizé Carrère

I wanted to know more about this. He explained that it was discovered when the lavaka formed, which is the way that quite a few precious stone deposits are revealed. When huge erosional landslides dislodge massive volumes of soil from a hillside, some treasures are bound to be unearthed along the way.

Over the next few months, I saw this several other times. I was even told that along the northwestern coast of Madagascar, many people sift through the soils at the mouths of rivers to collect flecks of gold that are carried down with the rain from eroded lands. This has allegedly resulted in people purposefully inducing erosion (lavaka) at higher elevations in order to release gold and other precious stones contained within hillsides.

This suddenly added an interesting twist to my research. While I’m focusing on what advantages or benefits are being realized from lavaka, which up until now have been largely perceived as something negative, I was torn on where to place this new bit of information. While many farmers can benefit financially from discovering a small mineral deposit on their land, I also know how quickly that can spin into a corrupted and greedy mess. Furthermore, the conservationist in me cringed at the idea of people intentionally eroding the land for earth’s treasures, something that we already have far too much of the world over.

So as we stood over this tourmaline deposit peering into the bottomless black hole, I asked the farmer what he thought about it. His response was a beautiful one, and suddenly his nonchalance about it all made sense:

“Ah”, he began as we sat looking out over the landscape, “the gains from that tourmaline deposit could never compare to what this land has provided, and will continue to provide, for the legacy of my family. If a deposit chooses to reveal itself on my soils and I can benefit from it, I will surely do so. But to resort to greed and seek it out, sacrificing the health and productivity of my land for those temporary gains? Never. That’s not the Malagasy farmer spirit”.

The farmer rests contemplatively. Photo: Alizé Carrère
The farmer rests contemplatively. Photo: Alizé Carrère

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