New Ocean Within Africa Could Take Millions of Years to Form

The Earth's tectonic plates have always slowly shifted over billions of years of our planet's history, carving out seas and pressing mountain ranges into existence.

One change that is expected in the Earth's relatively near geological future is for a rift in the middle of Africa to open, forming a new ocean in the middle of the continent.

Douwe van Hinsbergen, the chair in global tectonics and paleogeography at Utrecht University in the Netherlands, told Newsweek: "The East African Rift has long been recognized as a rift that may develop into an ocean like the Red Sea and the Gulf of Aden have done before."

The Earth's crust is made up of between 15 and 20 pieces known as tectonic plates, that float gradually atop the molten magma mantle below, according to the National Oceanic and Atmospheric Administration. The heat of the Earth's core produces convection currents in the mantle, causing the plates to drift in certain directions, moving apart from each other, pressing into one another, or splitting in two. These movements occur over millions and millions of years and are the reasons for the ancient continent of Pangea breaking up 250 million years ago and forming the continents we know today.

Geologists can predict how the plates will shift in the future, and forecast that the East African Rift in Ethiopia, Kenya, and Tanzania, among other African countries, will split open, forming a new ocean. How long it will take for this new ocean to emerge depends entirely on how fast the rifting of the plates occurs.

John Long, a strategic professor in paleontology at Flinders University in Australia, told Newsweek, "Based on tectonic spreading rates in East Africa that vary for 0.5-1 cm per year [0.2-0.4 inches per year], to open up a large enough rift to allow an ocean to come in, even a narrow one, say 5 km wide [3.1 miles], would take between 50,000-100,000 years coupled with what we know about sea levels rising."

"If seas rise by up to 0.7 m [2.3 feet] in the next hundred years or by 20-30m [65-100 feet] in the next 500 years with melting ice caps caused by the warming climate, it would happen much sooner," he said.

For comparison, human fingernails grow at a rate of around 4.2 cm per year, or 1.6 inches.

Different rifts move at different rates, with some plates moving apart from each other faster than others.

"The East African Rift formed already 30 million years ago, and its spreading is very slow. Normally, a true oceanic basin with ocean floor forms after about 300-400 km [186-248 miles] of extension, which, with the current rates, may take another 10 million years or more," van Hinsbergen said. "But in other cases, this occurred more rapidly, like in the Central Atlantic Ocean, where from initial breaking to oceanization took less than 15 million years, about 200 million years ago."

Scientists use signals transmitted from satellites to GPS receivers on land to measure plate movements and elevation changes.

"We don't have a lot of these continuously recording stations in Africa, but where we do have measurements, we can then use modern rates to predict where plates will be 1 million years or 5 million years from now," Cynthia Ebinger, a plate tectonics professor at Tulane University, Louisiana, told Newsweek. "We can also gain insight from dating rock units in ancient rift systems where we can get general opening rates."

"The general motions of the plates are predicted using global measurements from GPS and other space-based observations. These measurements give us estimates of modern plate motions that represent an 'instantaneous' motion, at least in terms of very slow geological processes. Are they representative of longer-term, or time-averaged processes over 100,000 or 1 million years? We use seafloor spreading anomaly patterns on the seafloor to track the motions of the plates over the past 180 million years, allowing us to see patterns in plate motion that then guide our future predictions," she said.

Predictions of the next 200 million years also indicate that Australia will move northwards, eventually colliding with East Asia.

If the East African rift did eventually become an ocean, it would have massive impacts on the geography and ecology of the continent we know today.

"Areas below sea level that are connected to the oceans will indeed flood with seawater. Already the Tanganyika rift has lake basins that lie below sea level, but they are filled by freshwater," Ebinger said.

Additionally, the parts of Africa to the east of the rift, including Somalia and other countries on the Horn of Africa, will shift further eastwards, eventually colliding with Asia.

"If the western branch of the East African Rift will become the new ocean, then there will be a new 'passive margin' forming," van Hinsbergen said. "The land that is now in the rift will subside, and the margins will become the site of big coral reef systems. The countries to the east of the rift will move with the new 'Somali Plate' towards India, and this actually may become kind of an Andes/Tibetan Plateau highland."

Neither we nor our children's generations will have to worry about this newfangled world geography, however, as the human lifespan is a mere blink in the eye of geographical time.

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