What happens to rock around a subducting slab? Do two colliding continental plates always cause volcanoes? What is a transform boundary? What do scientists believe is the force behind the plate tectonics theory? What does plate tectonics cause? What is the difference between normal faults and rift valleys?
Rift valleys sometimes occur near normal faults, but their formation is not related to these faults. Normal faults occur in the northern hemisphere, but rift valleys only occur in the southern hemisphere. The African plate, sometimes called the Nubian plate, carries most of the continent, while the smaller Somali plate carries Horn of Africa. Two arms of the Afar Triple Junction continue to widen in the process of seafloor spreading—the arm extending into the Red Sea and the arm extending into the Gulf of Aden.
As these rifts continue, the narrow valley created by the Gregory Rift the arm of the Afar Triple Junction located above sea level may sink low enough that the Arabian Sea will flood it. Separated from Africa by this new strait , Horn of Africa sitting on the Somali plate would become a continental island , like Madagascar or New Zealand. The Western Rift is one of the most biodiverse regions in Africa, featuring a narrow corridor of highland forest s, snow-capped mountains, savanna s, and chains of lake s and wetland s.
Rift lake s, formed as freshwater floods rift valleys, often mark rift valley systems. More than a billion years ago, for instance, the North American plate began a rifting process. A triple junction formed in the middle of the young continent, and deep rift valley developed.
Freshwater drained and collected in this rift valley, creating a lake. After millions of years, however, the rift failed. Today, the remains of that ancient rift lake, Lake Superior, rest atop one of the oldest and deepest rift valleys in the world. Lake Baikal, the rift lake over the Baikal Rift Valley in Siberia, is the deepest and oldest freshwater lake in the world. The deepest parts of Lake Baikal are 1, meters 5, feet , and are getting deeper every year.
In addition, over the past 25 million years, layers of soft sediment have accumulate d on the lakebed. The actual floor of the rift valley is more than 5 kilometers 3 miles deep. Lake Baikal also has the largest volume of liquid freshwater in the world—a staggering 23, cubic kilometers 5, cubic miles. Although the Dead Sea is not the world's deepest lake, the deep Jordan Rift makes it the lowest land elevation on Earth.
Unlike Lake Baikal, however, the Dead Sea is not a true rift lake as it was not formed entirely by the rift beneath it. The so-called Dead Sea Transform is a geologically complex area, where tectonic plates interact in many ways. Continental Rift Valleys. Very few active rift valleys are found on continental lithosphere. The Baikal Rift Valley is formed by a divergent plate boundary, where the Amur plate is slowly tearing itself away from the Eurasian plate, and has been doing so for about 25 million years.
The Amur plate is moving eastward at a rate of about 4 to 5 millimeters. The West Antarctic Rift is one of the most difficult rift valleys to study, because it lies beneath the massive Antarctic Ice Sheet , which can be more than 2 kilometers 1.
The Rio Grande Rift separates the Colorado Plateau , which is generally moving in a clockwise direction, from the older part craton of the North American plate. The most well-known rift valley on Earth is probably the so-called " Great Rift Valley System " which stretches from the Middle East in the north to Mozambique in the south.
The area is geologically active, and features volcano es, hot spring s, geyser s, and frequent earthquake s. Today, however, the Great Rift Valley exists as a cultural concept, not a scientific one. The northern part of the system is the Jordan Rift Valley. Millions of years ago, the Arabian Peninsula was connected to Africa. Seafloor spreading caused the Arabian and African plates to rift apart. The Indian Ocean flooded the rift valley between the continents, creating the Red Sea.
Today, Africa and Asia are connected by the triangle of the Sinai Peninsula. East African Rift. Throughout the East African Rift, the continent of Africa is splitting in two. The African plate, sometimes called the Nubian plate, carries most of the continent, while the smaller Somali plate carries Horn of Africa. Two arms of the Afar Triple Junction continue to widen in the process of seafloor spreading—the arm extending into the Red Sea and the arm extending into the Gulf of Aden.
As these rifts continue, the narrow valley created by the Gregory Rift the arm of the Afar Triple Junction located above sea level may sink low enough that the Arabian Sea will flood it. Separated from Africa by this new strait , Horn of Africa sitting on the Somali plate would become a continental island , like Madagascar or New Zealand.
The Western Rift is one of the most biodiverse regions in Africa, featuring a narrow corridor of highland forest s, snow-capped mountains, savanna s, and chains of lake s and wetland s. Rift lake s, formed as freshwater floods rift valleys, often mark rift valley systems. More than a billion years ago, for instance, the North American plate began a rifting process. A triple junction formed in the middle of the young continent, and deep rift valley developed.
Freshwater drained and collected in this rift valley, creating a lake. After millions of years, however, the rift failed. Today, the remains of that ancient rift lake, Lake Superior, rest atop one of the oldest and deepest rift valleys in the world.
Lake Baikal, the rift lake over the Baikal Rift Valley in Siberia, is the deepest and oldest freshwater lake in the world. The deepest parts of Lake Baikal are 1, meters 5, feet , and are getting deeper every year. In addition, over the past 25 million years, layers of soft sediment have accumulate d on the lakebed. The actual floor of the rift valley is more than 5 kilometers 3 miles deep. Lake Baikal also has the largest volume of liquid freshwater in the world—a staggering 23, cubic kilometers 5, cubic miles.
Although the Dead Sea is not the world's deepest lake, the deep Jordan Rift makes it the lowest land elevation on Earth. Unlike Lake Baikal, however, the Dead Sea is not a true rift lake as it was not formed entirely by the rift beneath it.
The so-called Dead Sea Transform is a geologically complex area, where tectonic plates interact in many ways. The most famous rift lakes in the world may be the series of narrow, deep rift valleys in the East African Rift known simply as the Rift Valley lakes. The Rift Valley lakes, stretching from Ethiopia to Malawi, are sites of amazing biodiversity.
Only Lake Baikal is deeper and holds more water. Like many freshwater Rift Valley lakes, Lake Tanganyika is home to hundreds of endemic species of cichlid fish. Rift valleys are typically deep and narrow. Photograph by Emory Kristof, National Geographic. African Great Lakes.
0コメント