Tectonic Plates Pulling Apart


In the land of death, scientists witness the birth of a new ocean Guardian - November 2, 2006

Fissures have opened in the Earth's surface in Afar as the Arabian and Nubian tectonic plates pull apart. Scientists say the process is the same as that which created the Atlantic. In Ethiopia's arid Afar region eruptions and earthquakes have created an open-air laboratory.

The nomads were terrified. For a week the ground had shuddered violently. Cracks opened up in the soil swallowing goats and camels. Sulphur-laced smoke rose out of the dark slits. After retreating to the hills, the nomads saw chunks of obsidian rock burst through the Earth's crust "like huge black birds" and fly 30 metres into the air. A mushroom cloud of ash dimmed the sun for three days. At night the new crater breathed flashes of fire. "They had experienced earthquakes before but never anything like this," said Atalay Ayele, a seismologist at Addis Ababa University, who interviewed the Afar tribes people soon after the volcanic eruption 13 months ago in this remote corner of north-eastern Ethiopia. "They said that Allah must have been angry with them."

But Dr Ayele, 37, and his colleagues wanted a scientific explanation. They knew the area was geologically unstable, but the number of earthquakes, 162 measuring more than four on the Richter scale in just two weeks, made them suspect that something extraordinary had happened deep underground. They asked a team of British-based scientists with access to satellite technology for help. When the results came back it seemed as unlikely as birds flying out of the ground.

Here in the Afar desert, one of the hottest and driest places on earth, the tribe had witnessed the birth of a new ocean. Images from the European Space Agency's Envisat satellite showed that a huge rift, 37 miles long and up to eight metres (26ft) wide, had opened deep in the Earth's crust. The tear, the largest observed since the advent of satellite monitoring, was created by a violent lateral rush of molten rock, or magma, along the fault line separating the Nubian and Arabian tectonic plates.

Tim Wright, a geologist at the University of Leeds who interpreted the satellite results, was astonished by the images and what they pointed to. "The process happening here is identical to that which created the Atlantic Ocean," said Dr Wright during a recent research expedition in Afar. "If this continues we believe parts of Eritrea, Ethiopia and Djibouti will sink low enough to allow water to flow in from the Red Sea." The findings caused a stir in the scientific community. This year teams from the UK, France, Italy and the US mounted expeditions to Afar, a region described by the British explorer Wilfred Thesiger as a "veritable land of death".

From above you can see vast black tongues of lava lapping at the desert sands, and rust-colored volcanoes with their lids long blown off. There are so many fissures and faults where the ground has opened and slipped that the Earth's skin looks like elephant hide.

The lunar geography reflects what lies beneath. Afar stands at the junction of three tectonic plates, which form the outer shell of the Earth and meet at unstable fault lines. The Nubian and Somali plates run along the Great Rift Valley, which spreads south from Afar. Branching out like a funnel to the north is the Arabian plate.

Tectonic plates across the globe are constantly shifting, though slowly, usually by a few centimeters a year, with the magma beneath the crust. The plates can collide, forcing the crust upwards and creating mountain ranges, as happened with the Himalayas. They can also slide past one another, as occurs along the San Andreas Fault, in California, a notorious earthquake zone.

The plates can also pull apart causing continents to break up and oceans to form. Early in this process, at the plate margins, the Earth's crust stretches and thins in the manner of toffee. Magma rises up, eventually cracking the crust and helping the plates drift apart. Between the fault lines the crust, now heavy with cooled magma, sinks to form a valley and then allows water from a nearby sea to rush in.

This is how the Atlantic was formed, separating Africa and Eurasia from the Americas. And this is what scientists believe is happening in Afar as the Arabian and Nubian plates pull apart. Parts of the region have already sunk to more than 100 metres below sea level, and only the highlands around the Danakil depression stop the Red Sea from rushing in.

Analysis of the new rift is providing an insight into the role of magma injection in cracking the Earth's crust and the pace at which continental break-up occurs. The last big "ocean spreading" occurred in Krafla, Iceland, in the mid 1970s, along the boundary of the North American and Eurasian plates that forms the Atlantic's mid-ocean ridge. But it took nine years to achieve what has occurred in Afar in a few weeks.

In recent months there has been more instability in Afar. After a series of earthquakes in June the rift widened by a further two metres. Hundreds of Afar nomads are still seeking refuge in a town 25 miles from the main fault zone, too afraid to go home. They may be wise; the scientists say there could be more violent earthquakes and eruptions. The new sea is predicted to be formed within about a million years. The separation of the Nubian and Somali plates along the Great Rift Valley could take 10 times as long. But that will be even more dramatic, for then Africa will eventually lose its horn. "Some people think that extreme natural phenomena happened only in historical times," said Cindy Ebinger, an American geologist leading the research in Afar. "But here we can see them happening right now."




Physical Land Bridge


A physical land bridge, in biogeography, is an isthmus or other land connection between what at other times are separate land masses which allows animals and plants to cross and colonize new lands. Land bridges are commonly created by regression, in which sea levels fall exposing previously submerged sections of continental shelf. Land bridges are also formed by upthrust at the edge of continental plates.

The most recent significantly low sea levels were about 20,000 years ago (during the Upper Paleolithic) when worldwide sea levels were about 120 meters below today's level. By 10,000 years ago, the sea level had risen to 20 meters below today's level.

The best-known example is the Bering land bridge, which joined present-day Alaska and eastern Siberia at various times during the Pleistocene ice ages, enabling humans to migrate from Eurasia to the Americas. Another land bridge may have connected Great Britain to Europe at around the same time.

A land bridge surviving to the present day is the Sinai, connecting North Africa with Southwest Asia. Hominids and humans probably migrated out of Africa through the Sinai.

A land bridge that rose from the sea floor because of upthrust at the edge of a continental plate is Central America. The Cocos Plate, an oceanic tectonic plate off the west coast of Central America, is being subducted in a convergent boundary under the North American Plate to the north and the South American Plate to the south. This caused first an island arc and then continuous land to emerge.

Before the theory of plate tectonics, it was believed that land bridges could explain the occurrence of species in separate continents. Many land bridges were thought up, cross-crossing large areas of ocean. They also apparently disappeared without a trace. Continental drift negated this theory.

Other Meanings Wikipedia

You need to pay attention to the movements of the tectonic plates. Soon you will hear them. Earth changes are one factor that bridge the gap of human consciousness from this reality to wherever ...

When you have time, let's do some automatic writing. Prepare a new Word Document. Copy and past the questions below then answer them without thinking, just type whatever comes to mind. Relax ... Let the words flow. Forget spelling and grammar.

You can also read the questions, or have someone ask them of you, while you meditate. Write down, or record, every symbol you see. You can have a friend do this with you, in person, or on the phone.

There is something about this land bridge crossing exercise that seems important for those who connect. For the others ... just walk on by.

Here we go ...

Visualize yourself crossing a land bridge.

As for me, I am always a male, with darker coarse skin, dressed in furs, walking east across the Bering Straight. As I travel, I evolve into someone else.

In a separate exercise, create a short children's story about a child who lives in that time frame and will cross your land bridge. Give the child a name, age, family, description, pet?, a limitation or challenge, and show how they overcome it. Think animated character, film, game, TV series ... If the information doesn't flow easily ... let it go.


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