The Amazon River

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Podcast Transcript

Located in the heart of South America is the Amazon, the world’s largest river. It isn’t just big, it is by almost any measure you can think of the world’s largest river, and it is so by a wide margin. 

In addition to the river itself, the Amazon basin is the location of one of the greatest collections of biodiversity on the planet. It is home to millions of species of plants and animals. 

Learn more about the Amazon, the world’s largest river, on this episode of Everything Everywhere Daily.

I’ve done several other episodes on the world’s great rivers, and in each one, I end up referencing the Amazon. Given how big and important the river is, I figured it was time for its own episode. 

The Amazon is the largest river in the world, and it isn’t even close. A full 20% of the world’s freshwater that flows into the ocean comes from the Amazon. 

On average, approximately 230,000 cubic meters, or 8,100,000 cubic feet of water flow out of the Amazon each second. 

To put that into perspective, that is more than the next seven largest rivers in the world…..combined. 

There is so much water flowing out of the Amazon that the sea level in the Caribbean is three centimeters higher than it should be because all of the water is carried north by the Caribbean Current.

If you remember back to my episode on the Nile River, the Nile might be the longest river in the world…or it might be the Amazon. 

The reason for the debate has to do with the fact that the lengths of both rivers are almost the same, and there is no set way to define the length of a river. 

The problem has to do with how you define the start and end of the Amazon. 

The source of the Amazon, despite the region having been extensively mapped, is still debated. It is usually defined as the farthest point of continuously flowing water that can travel to the river’s mouth. However, what if the farthest point doesn’t flow year around and sometimes dries up? What if each time you hit a tributary, you take the branch with the most water flow?

In the case of the Amazon, you get different answers depending on which definition you use.

Likewise, the endpoint of the river is in question. At the mouth of the river is a large island known as Marajó Island. The river flows north and south of the island. The endpoint is usually defined as north of the island, but it is also connected to the Para Estuary in the south, which would be a bit longer. 

So, if you want to, you can define the Amazon to be the world’s longest river, and you wouldn’t necessarily be wrong. The Amazon can be anywhere from 200 kilometers shorters than the Nile to 100 kilometers longer. 

The approximate length of the Amazon, which is usually rounded off because of the ambugity, is given as 6,500 kilometers or 4,000 miles.

The Amazon is also the widest river in the world. During the dry season, it can be 6.8 miles or 11 kilometers across, which would still be the widest river in the world. During the wet season, it can more than double, growing to 24.8 miles or 40 kilometers in width. 

The thing that really matters for a river isn’t the length or width of any particular channel of water. It has to do with the total basin which flows into the river. 

Not surprisingly, the Amazon river basin is the largest in the world. It covers an area of approximately 7,000,000 square kilometers or 2,700,000 square miles.

Water from several countries flows into the Amazon, including Bolivia, Peru, Ecuador, Colombia, Brazil, and small parts of Venezuela, Guyana, and Suriname. 60% of the basin is inside Brazil. By the time the Amazon enters Brazil, it is already the largest river in the world by water flow. 

There are over 1,100 tributary rivers that flow into the Amazon. 

The name Amazon was given by European explorers. The original name used by Europeans was the Marañón River. 

The name Amazon came from the 16th-century Spanish explorer Francisco de Orellana. During an expedition in the Amazon, he was attacked by a group of warriors which was led by a woman. 

This reminded him of the female Amazon warriors from Greek mythology. So, he dubbed the river the Amazon, and the name stuck. 

So, why is the Amazon so big? What makes it different than every other river in the world? 

It all has to do with the Andes mountains and the latitude it is at. 

Between 30 degrees north and 30 degrees south, winds tend to blow east to west. This area is also within the tropics, where it is warm. 

In the case of South America, that means that warm, moist air from the Atlantic blows over South America until it hits the Andes mountains. The Andes run north/south and serves as an effective barrier to moisture.

It precipitates out as rain and flows back down to the sea. Furthermore, there are elevated escarpments on the north and south of the river, which sort of makes the entire Amazon basin like a giant bowl.

If you look at an exaggerated relief map of South America, you can clearly see it. 

Believe it or not, there is a river below the Amazon which follows its general path. It is known as the Hamza River, and it is a slow-moving aquifer that lies 4 kilometers below the surface, is approximately 6,000 kilometers long, and is wider than the Amazon. 

One of the amazing facts that geologists have discovered about the Amazon is that river might be older than the Andes. About 10 million years ago, the Amazon basin probably drained north into the Pacific Ocean, just to the west of Panama today. 

The north-south orientation of the Andes is the reason why the Amazon is so big. The Himalayas run roughly east-west and is located closer to 30 degrees north latitude, so it doesn’t block as much moist air. It blocks some, but nothing like the Andes. 

The enormous Amazon basin, coupled with its tropical latitude, results in the Amazon rainforest, the world’s largest. 

The Amazon rainforest has often been called the lungs of the world, but this isn’t quite true. It is true that the plants in the rainforest produce the equivalent of 20% of the Earth’s oxygen. However, just as much oxygen is taken out of the atmosphere by decomposing organic matter on the floor of the rainforest. 

The Amazon rainforest is home to the largest amount of biodiversity on the planet. A full one-third of all animal species in the world are believed to be in the Amazon. 

It is impossible to know exactly how many species live in the rainforest, but the number is in the many millions.  There are new species of insects, plants, and animals being discovered all the time. 

There are several notable species that live in the Amazon. One is the Amazon river dolphin, the largest species of freshwater dolphin in the world. They are notable for their pink color.

The Amazon is also home to the giant otter, which is the largest weasel in the world, as well as the green anaconda, which is the world’s largest snake. 

The most famous species is probably the piranha. Most of what people know about piranhas are myths and legends. People think that if you fall into water with piranhas, you’ll be shredded apart in seconds. 

Much of the public perception of piranhas came from President Teddy Roosevelt, who took a trip to the Amazon in 1913. There he witnessed piranhas devour an entire cow. 

In reality, what happened was the villagers he visited knew he was coming, so they netted a large number of piranhas and held them without feeding them.

When the president arrived, they put an abnormally large number of  hungry fish into the water all at once and then fed them a cow. 

Piranhas do have a nasty bite, but they mostly feed on dead or wounded animals in the water. In cases where drowning victims have been pulled out of the river, there have been bites, but no cases of an entire body being torn apart. 

Also, piranha species are not all carnivorous. Most are omnivorous, and a few species feed solely on plants. 

However, the most interesting species in the rainforest are humans. 

The Amazon is home to the largest number of uncontacted tribes in the world. All five of the Amazon countries have people who have remained isolated from the rest of the world and live according to their traditional ways. 

Most of these tribes have had some sort of limited contact in the past, but their remote location makes them difficult to reach.

This is probably for the best, as many tribes have fallen victim to ranchers and miners who wanted to take the land that they lived on. 

The Brazilian Department of Isolated Indians estimates there are 67 uncontacted tribes living just in Brazil. 

Researchers have discovered the remains of ancient settlements in the Amazon, which date back 10,000 years. What they have discovered has completely upended our understanding of how humans lived in the region. 

They may have created artificial forest islands, which were mounds of land that stayed dry even during flooding during the wet season. It might be one of the earliest examples of plant domestication and agriculture ever found and evidence that early inhabitants actually shaped the rainforest to their benefit. 

There is still quite a bit of research that needs to be done as this is a very difficult palace to gather evidence. 

There are also humans living in the Amazon basin who are in contact with the rest of the world. 

In previous episodes, I spoke about the geography of major rivers and how they determine the fate of those living near them. 

For example, the Congo is difficult to navigate due to the large waterfalls and rapids in the river. The Nile can’t easily be navigated above the cataracts near the Egypt-Sudan border, and it flows mostly through desert.  

The Mississippi River basin has almost no waterfalls or rapids, plus it flows through extremely productive farmland. 

The Amazon is a very navigable river. There are no waterfalls or rapids until you get very close to the headwaters near the Andes. However, the Amazon basin has, for the most part, been a very unattractive place for people to live. 

The soil in the rainforest is actually very poor, which doesn’t make for good farming. Moreover, whenever you clear land, you have to have to constantly fight back against the jungle, which wants to reclaim the land. 

There are few roads in the Amazon basin which makes transportation difficult, and it would be difficult to build roads in the region even if you wanted to. 

There are currently no bridges over any part of the Amazon River. 

In theory, while a bridge could be built, there is currently no pressing need for one. There is nothing to connect it to, and not enough people to use it. Moreover, building on soft, wet land over a river that regularly floods and meanders would be incredibly expensive.

The entire Amazon basin only has a population of 26 million people giving it one of the lowest population densities on Earth. 

The Peruvian city of Iquitos is located in the Amazon basin, has a population of close to half a million people, and isn’t connected to the rest of the world by road. The only way there is by plane or boat. 

Other major cities in the Amazon basin include Manaus, with a population of 2.2 million, Belém with a population of 1.5 million, and Macapá, with a population of half a million. All are in Brazil.

So despite being such a huge navigable river, the Amazon doesn’t have as much of an economic impact as most other great rivers of the world. Mostly because of the land it flows through and the small number of people who live alongside it. 

I’ll close this discussion of the Amazon River by mentioning one of the natural oddities which take place on the river twice a year. 

Despite the enormous amount of water that flows out of the Amazon, when conditions are just right, water can sometimes flow into the Amazon from the Atlantic Ocean. 

This event is known as a Pororoca. It is a tidal bore that occurs on the full or new moons when tides are the highest, and the effect is most pronounced near the equinoxes in March and September.  

At the high tide, a single wave will flow into the river, which can go as far as 800 kilometers or 500 miles upstream. 

Needless to say, whenever there is a wave, you will find surfers. Surfing the Pororoca has become popular, and there is now an annual competition to see who can surf the wave the longest. 

The record ride was set in 2003 with a ride of 12.5 kilometers or 7.8 miles, lasting 37 minutes.

Despite all the travels I’ve done around the world, I still have yet to visit the Amazon. It is near the top of my list of places I would still like to see. 

And for good reason…

The Amazon River, basin, and rainforest make up one of the greatest natural wonders on planet Earth. 

The Executive Producer of Everything Everywhere Daily is Charles Daniel.

The associate producers are Thor Thomsen and Peter Bennett.

Today’s review comes from listener Michael Critz over on Apple Podcasts in the United States. They write

Caution Contents Highly Addictive

Everything Everywhere Daily is the only binge-worthy podcast.

More than once, I’ve struggled through some long-form podcasts for a week. Afterwards, I’d have several episodes of Everything Everywhere Daily queued up in my player. I’d listen to an episode, then I’d have to listen through all of them because the subject matter is interesting — and this part is important — in different ways.

Topics that slide between history, science, and culture topics that tickle the parts of my brain that want to sneak a bottle of water past airport security, experiment with electricity, contemplate museum theft, and/or get an advanced degree in physics.

Thanks, Michael! I would like to go on the record to state that Everything Everywhere Daily and its host are not responsible for any museum thefts which are the result of listening to this podcast.

However, if you do conduct a museum theft, please send me an email. I’m sort of curious as to how it goes. 

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