East African Rift

The ground in East Africa is pulling apart.

This happens very slowly. The land splits into two big pieces. This split makes a long crack in the earth.

The crack makes deep lakes and tall mountains. It also makes big volcanoes. Some volcanoes have hot, runny lava.

Many old bones have been found here too. These bones help us learn about people from long ago. The earth is still changing every day.

The East African Rift is a giant crack in the Earth.

It started to form about 22 to 25 million years ago. Right now, the land is splitting apart. The African plate is breaking into two new pieces. We call these the Somali plate and the Nubian plate. They move apart by about 8 to 9 millimeters every year. This slow split creates many different features.

Deep basins and large lakes form in the valley.

Many of the African Great Lakes sit here. The rift also makes tall mountains and big volcanoes. Some volcanoes, like Mount Kilimanjaro, were made by this process. One special volcano is called Ol Doinyo Lengai. Its lava is very runny, like olive oil.

The rift also helps us learn about our past. Many old bones have been found in the valley. These are fossils from ancestors of humans. One famous find was a skeleton named "Lucy." These bones help scientists study how humans changed over time.

The East African Rift is a massive, active zone where the Earth's crust is splitting apart.

This process is part of a larger system that once included a place called the Great Rift Valley. It stretches all the way north to a region known as Anatolia in Asia Minor. Right now, the African plate is dividing into two smaller pieces. Scientists call these the Somali plate and the Nubian plate. These plates move away from each other at a rate of 8 to 9 millimeters every year. This slow movement creates deep valleys and many of the African Great Lakes.

This split happens through a step-by-step way it works. First, the ground begins to thin and crack in certain spots. This thinning can cause volcanic activity to start. As more magma moves into these cracks, it can make the ground even thinner. Eventually, the crust behaves like a ridge found on the ocean floor. This cycle of thinning and volcanic activity helps the plates pull apart. The rift also has different branches that follow different paths. One branch, the Eastern Rift Valley, runs through Ethiopia and Kenya into Tanzania. The Western Rift Valley goes through countries like Uganda, Rwanda, and Burundi.

People have studied this amazing place for a long time to understand its history. In 1972, some thought the rift was caused by how heavy the crust was. Since the 1990s, new evidence has pointed to mantle plumes. These are hot areas rising from deep inside the Earth. In 2009, a new theory was shared about how volcanoes and plate movement work together. Marine geologist Kathleen Crane says this rift might eventually split eastern Africa away from the mainland. This huge event could take tens of millions of years to happen. Scientists use tools like seismic tomography to look deep under the ground.

There are many important facts about the rift's landscape and its volcanoes. The rift includes famous mountains like Mount Kilimanjaro and Mount Kenya. Some volcanoes are very active, such as Erta Ale in Ethiopia. Erta Ale has had a lava lake since at least 1906. Another volcano, Ol Doinyo Lengai, is very special because its lava is runny like olive oil. The rift is also the largest place for earthquakes in this system. Most of these quakes happen near the Afar Depression. In the last century, some earthquakes there reached a magnitude of 7.0.

The rift changes more than just the ground; it even changes the weather. High areas like the Ethiopian Highlands catch more rain than the dry lowlands. Large lakes like Lake Victoria create water vapor that affects the air. The valleys also act like paths for the wind. These winds can make East Africa drier while helping the Congo Basin stay rainy. The rift is also a treasure chest for history. It is a great place to find fossils of human ancestors. A famous skeleton named "Lucy" was found here by Donald Johanson.

The East African Rift (EAR) is an active continental rift zone in East Africa. It is a massive area where the Earth's crust is actively splitting apart. This process is part of a much larger tectonic system. In the past, this system was known as the Great Rift Valley. It extends far north into Asia Minor, a region called Anatolia. The rift is a developing divergent tectonic plate boundary. This means two large pieces of the Earth's crust are moving away from each other.

At this boundary, the African plate is splitting into two new plates. These are called the Somali plate and the Nubian plate. They move apart at a rate of about 8 to 9 millimeters every year. The rift system is complex and includes three microplates. These are the Victoria microplate in the north, and the Rovuma and Lwandle microplates in the south. The Victoria microplate is actually rotating anti-clockwise. This rotation happens because of the different strengths of the lithospheric regions nearby.

Scientists have different ideas about how this rift formed. In 1972, some researchers thought differences in crustal density caused it. However, since the 1990s, evidence has supported the idea of mantle plumes. These are columns of hot material rising from deep inside the Earth. A more recent theory from 2009 suggests a feedback loop. In this model, magmatism and plate tectonics work together. As the lithosphere thins, it creates volcanic activity. This magmatic activity then thins the lithosphere even more. Eventually, the thinning crust behaves like a mid-ocean ridge.

The rift follows several different paths across the continent. North of the Afar triple junction, it splits into two directions. One path goes west to the Red Sea Rift. The other path goes east to the Aden Ridge in the Gulf of Aden. South of the triple junction, there are two main branches. The Eastern Rift Valley, or Gregory Rift, includes the Main Ethiopian Rift. It runs through Kenya and into northern Tanzania. The Western Rift Valley includes the Albertine Rift. This branch passes through the Democratic Republic of the Congo, Uganda, Rwanda, and Burundi.

Volcanic activity is a major feature of this rift system. Many famous mountains, like Mount Kilimanjaro and Mount Kenya, were created by the EAR. Some volcanoes are very active. Erta Ale in Ethiopia has had a summit lava lake since at least 1906. Another unique volcano is Ol Doinyo Lengai. It is the only active natrocarbonatite volcano on Earth. Its lava is very runny, with a viscosity similar to olive oil. The rift is also the largest seismically active rift system on Earth. Most earthquakes occur near the Afar Depression. In the last century, some earthquakes reached a magnitude of 7.0.

The rift system also has a massive impact on the global climate. High elevations like the Ethiopian Highlands catch more rainfall than the dry lowlands. Large lakes in the rift, such as Lake Victoria, create water vapor. This vapor affects weather patterns across East Africa through lake breeze systems. The east-to-west river valleys also influence the wind. They can accelerate winds toward Central Africa. This helps keep the Congo Basin rainforest rainy while making East Africa drier. The rift also affects the Somali Jet, which is a major wind system in the Indian Ocean.

Finally, the East African Rift is a vital site for studying human history. The rapidly eroding highlands fill the valleys with sediments. This environment is excellent for preserving fossils. Many bones of hominid ancestors have been found here. One famous example is "Lucy," a partial skeleton found by Donald Johanson. She lived over 3 million years ago. Other important discoveries include 10-million-year-old apes like Chororapithecus abyssinicus. These fossils help scientists understand how humans evolved over millions of years.