The East African Rift

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Podcast Transcript

Today there is a giant rift that is tearing the continent of Africa apart.

..and I mean this quite literally because the rift isn’t cultural, economic, or political, it’s geologic.

In several million years, Africa will be split into two continents, and while the process will take a long time, you see ample evidence for it right now.

Learn more about the East African Rift and how it has shaped the modern continent of Africa on this episode of Everything Everywhere Daily.

Geologically speaking, Africa is a very old continent. You don’t see many major mountain ranges in Africa for this reason. Because it is so old, there has been more time for erosion, which has made it relatively flat. 

However, there is active geology going on in Africa, it is just different than the type which is going on in the rest of the world. 

If you remember back to my episode on plate tectonics, the Earth’s tectonic plates are responsible for most of the earthquakes and volcanoes on the planet. 

A collision of tectonic plates often forms mountain chains. For example, the Himalayas were formed by the Indian subcontinent colliding with Asia. 

Most of the Ring of Fire around the Pacific is the result of an ocean tectonic plate subducting under a continental plate. 

…but if plates collide with each other, then that means somewhere else, they have to be splitting apart. These regions are called rifts.

Most of the rifts on Earth are found in the middle of oceans. Both the Atlantic and Pacific have major rifts which run for thousands of miles. 

There are actually only two places on land where you can see two tectonic plates splitting apart. The first is in Iceland, which is actually just a part of the Mid-Atlantic Ridge. 

The other is in East Africa. 

In the case of East Africa, it isn’t two different plates moving away from each other, it is one large continental plate that is literally splitting apart. 

It is the result of the interaction between three or two, depending on how you define it, tectonic plates. 

There is a triple junction of plates located where the Arabian Peninsula comes closest to Africa and where the Red Sea and the Gulf of Aden meet. 

Here the Arabian plate meets the point where the African plate is starting to split. On the east is the part of the African Plate now known as the Somali Plate, and to the West is the part of the African Plate known as the Nubian Plate. 

The entire East African Rift that I’ll be talking about is part of a larger rift system that extends up the Red Sea and is responsible for the Dead Sea. 

The reason I’m doing an episode on the East African Rift is that so many of the interesting geological formations in Africa are all due to the rift. Once you understand the rift, you can look at a map and clearly see where it runs. 

The start of the rift begins at the closest point of land to the triple junction. This area is known as the Afar Triangle. The Afar Triangle consists of the nations of Eritrea, Djibouti, Ethiopia, and Somalia. 

The rift then goes straight through the country of Ethiopia and then snakes down the western side of Kenya until it gets to a point parallel with the southernmost part of Lake Victoria.

This section is the Eastern Rift Zone, also known as the Gregory Rift, named after John Walter Gregory, the geologist that first studied it.

Then there is another section which is west of Lake Victoria, starting roughly at the northernmost part of the lake. This runs down the border of the Democratic Republic of Congo and Uganda, then Tanzania, and then Zambia, before turning and going down the length of Malawi and then cutting across Mozambique. 

This is the Western Rift or the Albertine Rift.

So if you can envision this, there are two sections that are not contiguous that run parallel to each other for a stretch on either side of Lake Victoria.

The area around Lake Victoria has been dubbed a microplate, and it is actually rotating counter-clockwise from the two rifts on either side of it.

The average rate at which the plates are pulling apart is approximately 7 millimeters per year on average. That might not seem like much, but in geologic terms, it’s pretty rapid. It means that every so often, in segments of the rift, there will be new cracks and chasms that form.

In 2018, a new crack in the ground appeared out of nowhere in Southwestern Kenya. The crack was 50 feet or over 15 meters deep and as wide as 60 feet or 18 meters across. 

Geology aside, the reason I wanted to do an episode on the East Africa Rift is that the rift is responsible for, or is the location of, so many of the notable features on the African continent. 

Let’s start with the northern section of the Afar Triangle. This is the location of the Danakil Depression. 

The Danakil Depression is one of the lowest, driest, and hottest places on Earth. 

I visited the Danakil Depression in Ethiopia several years ago, and it was unlike any experience I’ve ever had traveling. 

I witnessed temperatures of 50C or 122F, which was the hottest I’ve ever experienced. The village Dallol in the Depression is the hottest place in the world where people actually live.

There are incredible sulfur springs that exist that have some of the most acidic places on the planet. 

It is also the home of the Erte Ale volcano. Erte Ale is unlike other volcanoes in that it is in an open pool of lava that can be accessed by walking up to the lip of it. 

The Danakil Depression is also home to one of the most ancient salt harvesting industries in the world. Men there still chop slabs of salt from the ground and ship it to a salt processing center via camel caravan.

In Southern Ethiopia is the Omo Valley, created by the eastern rift. The Omo Valley is home to many people who still live according to their traditional ways, including the Kara, Hamer, Surma, Mursi, Dassanech, Banna, Tsemay, Erbore, and Ny-an-ga-tom peoples. They are known for their elaborate body adornments, including lip plates and ritual scarring.

As the rift moves south, going through Ethiopia, you will find a series of small rift lakes. When you reach the border of Kenya, you’ll find the first of the major rift lakes in Africa, Lake Turkana. More on rift lakes in a bit. 

As the eastern rift goes through Kenya and eventually Tanzania, immediately to the east, you will find several of the tallest peaks on the continent, including Mount Kenya and Mount Kilimanjaro, just over the border in Tanzania. 

These mountains are volcanoes that were created as a direct result of the movement of the plates in the rift zone. 

Also, in the rift zone, you will find Serengeti National Park in Tanzania and the Massai Mara game reserve in Kenya. 

The East African Rift actually defines the Ngorongoro crater. The rift created the eastern and southern walls of the crater. 

Collectively, all of these places are the home of the Great Migration, where approximately 1.8 million wildebeests migrate every year from Ngorongoro to Massai Mara, where they seek better grazing grounds. 

Not far from the Ngorongoro Crater is the Olduvai Gorge. The gorge is part of the rift system and was were fossils of some of the oldest human ancestors were found. 

As I mentioned before, between the southern part of the eastern rift and the northern part of the western rift lies Lake Victora, one of the largest lakes in the world. 

Victoria is not a rift lake per se, but it was created because of a drainage basin that arose due to the eastern and western rifts on either side of it.

To the west of Lake Victoria starts the western rift. 

Here you can very clearly see on any map of Africa where the rift runs because it is defined by a series of rift lakes. Starting along the border of Uganda and the Democratic Republic of the Congo and going south, you will see a chain of long slender lakes. 

These lakes are literally formed by the plates splitting apart and the gaps between them being filled with water.

The lakes in the western rift are much larger than those found in the Eastern Rift, and they include some of the world’s largest lakes. 

In the north, you find Lake Albert,  Lake Edward, Lake Kivu, and Lake Tanganyika.

Lake Tanganyika is the largest of the rift lakes and the second deepest lake in the world after Lake Baikal in Russia. 

The southern rift lakes include Lake Rukwa, Lake Malawi, Lake Malombe, and Lake Chilwa. Lake Malawi is the second largest of the rift lakes.

Collectively, the rift lakes are home to an incredible amount of aquatic diversity and species that are found nowhere else on Earth. They are also home to over 800 species of cichlid fish, which are popular fish for home aquariums. 

These lakes also have hidden dangers lurking under the surface. If you remember back to my episode on Limnic Eruptions, some lakes, such as Kivu, have enormous amounts of methane in their lake bed, which, if it came to the surface, would be an enormous disaster for those living around the lake.

Just as the eastern rift was responsible for mountains, so too is the western rift. 

The Virunga Mountains can be found mostly in the Democratic Republic of Congo, with small parts in Uganda and Rwanda. The Virunga mountains are volcanic, just like their counterparts to the east, and they also are the home to the mountain gorilla. 

I’ve just gone over a lot of things pretty quickly, but the point I wanted to make is that so many of the highlights of Africa are all the result of a single geologic feature that runs through the continent. 

Large lakes, tall mountains, exceptional wildlife, unique cultures, and even human evolution all have come about from the splitting of the African tectonic plate. 

In addition to everything I just mentioned, the East African Rift also holds a great deal of potential. 

Earlier, I mentioned that the only other place on Earth where you could see a rift like this on land was in Iceland. It just so happens that Iceland produces the highest percentage of geothermal energy in the world, and that is not a coincidence. 

A rift signifies a thinning of the Earth’s crust which makes it easier to tap into the heat which exists below the surface. That means that much of East Africa along the rift has the potential to become a geothermal powerhouse, as it is vastly larger than all of Iceland. 

Looking forward into the distant future, the East African Rift will completely reshape the map of Africa. Millions of years from now, most of the African rift lakes will be connected, forming a massive inland sea. At some point, in tens of millions of years, East Africa will completely break off from the rest of Africa to form a new continent. 

We have no idea what the shape of this new continent will be as it is impossible to predict where the fracturing in the rock might take place. 

It is possible that it could be one land mass, or it could splinter into several different islands. It will also mean the creation of a new ocean or sea between the two new continents.

The East African Rift is one of the most important geologic features on the Earth. The next time you look at a map of Africa or even a map of the world, take a closer look at the region of East Africa, and you will find it impossible not to see this feature that has always been there.

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 bernard over on Podchaser. They write:

Now there is a podcast that puts the P in Perfect and the A in Awesome. So how did Joe Rogan get millions of dollars from Spotify for his podcast and not Gary? Things that make me go hmmm. Maybe there should be a podcast on that one. Lol. 

Gary, you do a fantastic job. I went through your entire episodes in one weekend and got my twin nieces, and my nephew hooked, and they have gone through all the episodes. The other day I asked them what they think of the podcast, and they all loved it, but my nephews says the history episode are very Eurocentric. 

He meant it not as a critique, but he is curious how you pick your topics and what was your favorite continent you visited in the 10 years you traveled around the world, and frankly, I’m curious too, as I plan to venture on a similar journey. Keep up the good work!

Thanks, Bernard! As for your nephew, his critique is not wrong, and it is something I’ve addressed in previous episodes. Ultimately, I’m limited to my background and knowledge, but I am always open to suggestions for show ideas. 

As for a favorite continent, that is an impossible question to answer. Continents are so vast and have so many different regions that it is impossible to lump so much together. 

Remember, if you leave a review or send me a boostagram, you too can have it read on the show.