Flowing with their cerulean, turquoise, yellow-green strings, they captivate your eyes, and you submerge deep into its heart to find peace. Or to look for the beauty that respites within its watery heart. You might have already guessed what these endless strings are. Oceans, a body that originates way before Adam and Eve saw the skies of the world. They are eternal, just like how Alfred Lord Tennyson hears them saying,” For men may come, and men may go/, But I go on forever.” While some of us see the Earth for long, short, or shorter times, oceans never fade, nor does their vibrant color and beauty. Have you ever thought, where might these eternal bodies originate from? Where are their homes? And where are they searching for it? Oceans might seem to be mighty, fierce, and bodies who dwell with all the storms alone. Yet their mightiness is born rather than entitled. They originate just like us and then break into branches that flow around the entire curves and cracks of Earth. Like the nomads, oceans change homes. They do not do it voluntarily, but it is their mother, nature, which makes them do it.

Oceans refer to the large interconnected water bodies which cover the major surface of Earth, brightening their blues amongst the browns and greens. They get their name from a classical antiquity figure of Oceanus, believed to be elders of Titans in Greek mythology. They are believed by ancient Greeks and Romans to be the divine personification of a gigantic river that binds the universe. The concept of this Oceanus also has a connection with the Indian holy scriptures of Vedas, where it is said to be the prediction of dragon Vrtra, who captures the cows and rivers. In relation to this, the Oceanus was also represented with a dragon-tail on some ancient Greek vases. Today, we commonly know five oceans that breathe life into Earth and are responsible for the blue shades of our planet. From the descending order, we have the Pacific ocean, Atlantic ocean, Indian ocean, Antarctica ocean, and Arctic ocean. These oceans then divide into numerous seas, rivers, lakes, streams, brooks, ponds. Oceans are pure cycles. They break into fragments and return to their original shape after traveling the world. Not all the oceans are at the same spot. They spread across the seven continents, Asia, Africa, Australia, North America, South America, Europe, and Antarctica.

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Unlike some of us, who dwell in a certain land we call native and decide to spend our life on it, oceans shift. They shift from their places as nature keeps on adapting to changes wholeheartedly. Much of life’s history has taken birth from the oceans, but we remain unaware of it. The lives as well as the waves of oceans have been evolving and shifting their destinations for over 3 million years. The blue shade which we have today did not exist during our planet’s infancy; when the solar system was yet in its molding state, Earth’s surface was bombarded with numerous asteroids and comets. Since the birth of Earth, for 500 million years, the environment has remained highly unstable and uncertain. Between these asteroids and comets bombardments, scientists yield the belief that there was enough time for the vaporized water to condense and settle on Earth’s surface. As per the results of recent scientific studies, our entire planet was covered with the ocean for 150 million years, about 4.4 billion years ago. This was further justified with the discovery of ancient zircon crystals, which had the temperatures to melt and destroy other rocks, and they were found during those peculiar times. It is only with the movements of oceans, closely linked with the shift of continental lands, that oceans now cover 75% of the Earth.

Oceanic crust rocks are responsible for the shift in their positions. This shift is also inclusive of the shift in continental rocks. Ocean crust is denser than continental crust, though both are less dense than the underlying mantle. The continents can be considered as thick blocks of crust “floating” on the mantle, similar to icebergs that float on water. Oceanic crust floats on the mantle too, but due to it being denser, it doesn’t float as high as the continental crust. This is the reason the mainlands lie helpless above ocean level, and maritime outside lies underneath ocean level and is covered by water. It was the discovery of the magnetic anomalies on the seafloor, together with other evidence, that finally led to a better understanding of plate tectonics. The Earth’s surface is divided into a number of plates. These plates are composed of the crust, and the top parts of the mantle, make up the lithosphere. The plates are about 100 km thick. As a new lithosphere is created, the old lithosphere is destroyed somewhere else. Otherwise, the Earth would need to continually extend to account for the new lithosphere. The lithosphere is destroyed in the trenches. A trench is formed when two plates collide, and one plate dips below the other and slides back down into the mantle. This downwards movement of the plate into the mantle is called subduction. Subduction is the process that produces earthquakes and volcanoes, also underwater. This implies that oceans have gone through drastic positional changes.

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The continents have been carried long distances by the moving seafloor, and the ocean basins have changed in size and shape. In fact, new oceans have been born. Knowledge of the process of plate tectonics has allowed scientists to reconstruct much of the history of these changes. Scientists have discovered, for example, that the continents were once united in a single supercontinent called Pangaea that began to break up about 180 million years ago. A prominent theory that explains the shift in ocean positions is Continental Drift Theory proposed by Alfred Wegner in the year 1912. Let’s look deep like the oceans in this theory, which focuses on continental shifts and ocean positioning.

First things first, Continental Drift theory explained how continents shift position on Earth’s surface. Alfred Wegener, who was a geophysicist and meteorologist, explained how the continents change their destinations along with why look-alike animal and plant fossils, and similar rock formations, are found on different continents. Wegner held the belief that all the continents were once joined together in an “Urkontinent ” before breaking up and drifting to their current positions. These floating land masses sometimes plow through oceans and into each other. Wegner was convinced that all the continents were a part of a single landmass known as “Pangaea.” Pangaea existed about 240 million years ago. By about 200 million years ago, this supercontinent began breaking up. Over millions of years, Pangaea separated into pieces that moved away from one another. These pieces slowly assumed their positions as the continent we recognize today. To prove this idea, he listed the below example:

The east coast of South America and the west coast of Africa seem to fit together like pieces of a jigsaw puzzle, and Wegener discovered their rock layers “fit” just as clearly. South America and Africa were not the only continents with similar geology. Wegener discovered that the Appalachian Mountains of the eastern United States, for instance, were geologically related to the Caledonian Mountains of Scotland.

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Several pieces of evidence work parallel with Wegner’s theory of Continental Drift. Identical rocks were found on both sides of the Atlantic Ocean. Wegener said the rocks had formed side-by-side and that the land had since moved apart. Mountain ranges with the same rock types, structures, and ages are now on opposite sides of the Atlantic Ocean. Another proof is of the Appalachians of the eastern United States and Canada, which are just like mountain ranges in eastern Greenland, Ireland, Great Britain, and Norway. Wegener concluded that they formed as a single mountain range that was separated as the continents drifted. However, the theory has also received backlash. Henry Frankel, an emeritus professor at the University of Missouri-Kansas City and author of the four-volume “The Continental Drift Controversy,” says that there is the irony that the key objection to continental drift was that there is no mechanism, and plate tectonics was accepted without a mechanism,” to move the continents. Wegner failed to explain the trigger mechanism of Pangaea 200 million years ago. The breaking and joining sequences of the continents were not explained through this theory. Errors and vagueness can be experienced in Wegner’s theory regarding the formation of mountains, islands, and festoons.

Wegner’s theory can be considered a pioneer for other evolving theories, trying to explain the oceanic and continental shifts. This theory includes PLate Tectonic theory, which is widely accepted. This theory also explains that Earth’s crust is fractured into rigid, moving plates. In the 1960s, through magnetic surveys of the ocean floor and through the seismic listening networks built to monitor nuclear testing, scientists developed plate edges. Alternating patterns of magnetic anomalies on the ocean floor indicated seafloor spreading, where new plate material is born. Magnetic minerals aligned in ancient rocks on continents also showed that the continents had shifted relative to one another.

Another theory that proposes the ideas on continental and oceanic positioning changes is Convectional Current Theory, by Arthur Holmes. This theory believes that the heat which is generated from the radioactive decay of substances deep inside the Earth (the mantle) creates magma which consists of molten rocks, volatiles, dissolved gases, among other materials. According to the theory of seafloor spreading, convectional cells are the force behind the drifting of continents. Ocean plates get subducted under the continental plates (since ocean plates are denser than continental plates) when these two types of plates converge. The collision of plates is followed by earthquakes and volcanoes.

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An article published by the British Broadcasting Corporation (BBC) in the year 2016, shift continents and their position will lead to the existence of only one continent. This Deja Vu experience is called “Pangaea Proxima.” A supercontinent is on its way, and possibly then, you can walk through Australia to Alaska or Patagonia to Scandinavia. Australia, in near fifty million years, will collide with southeast Asia while Africa will push right towards southern Europe. The Atlantic will be a far wider ocean than how it is currently. Geologists are in a continuous quest to know the positioning of earth plates and the change it has impacted in the positions. So, next time, if there is an earthquake, you need to know that your land has changed its position just like you do!

~Saima

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