The Great Rift Valley is a continental rift in Africa. The rift system is created by two diverging continental plates. The Nubian and the Somali plates are the diverging plates. As the plates move apart, a large valley is created. Many volcanoes and lakes mark the valley floor.
Origin of the Great Rift Valley
The Great Rift Valley is a 6,000 kilometer chain of trenches in East Africa. The system of trenches is the result of diverging tectonic plates. As the Nubian and Somali plates moved apart the center collapsed into a series of trenches. This rift system is about 35 million years old. The plates continue to diverge and in time, the continental rifts will become oceanic rifts. When this occurs, the Somali plate will break away from the African continent.
Another example of continental plate divergence is the Baikal Rift Zone in Siberia, Russia. The Great Rift Valley is undergoing the same process as the MidAtlantic Ridge. However, the MidAtlantic Ridge is created by diverging oceanic plates.
Branches of the Continental Rift
Western Rift
The Rift Valley has two branches. The western (Kenya) rift has very high mountain ranges. For example, the Virunga Mountains is a volcanic chain with eight active volcanoes. The western rift also has the African Great Lakes. Lake Tanganyika and Lake Malawi are two of many lakes in this branch. The floor of the rift is also is deeper than the eastern rift.
Eastern Rift
The eastern rift (Ethiopian) is less developed than the western rift. The valley floor is not very deep and is not filled with a lake system. This part of the continental rift is also where research has uncovered the fossils of early humans. Lakes in the eastern rift are fewer in number and shallow. The rift is active with volcanoes. The highest mountain in Africa, Mount Kilimanjaro is found here.
Reflections
Vocabulary
- continental rift
- divergence
- tectonic plate
Notes
- The Rift Valley is a continental rift in East Africa.
- It consists of two branches.
- Remains of early human fossils have been discovered in the eastern branch.
Bibliography
- A Lithosphere Study Guide
- About the Surface of the Earth
- Plate Tectonics, The Geological Society.
