Nearly 300 million years ago, the geography of the Earth was drastically different than it is today. This time period, between 280 million and 230 million years before present, was known as the late Paleozoic to early Mesozoic Era, and it was during these periods that Earth consisted of one collective ocean, called Panthalassa, and one single land mass or supercontinent known as Pangea. This name stems from the Greek word ‘pan’ meaning all or whole, and Gaia which refers to Mother Earth.
It is estimated that Pangea was originally formed some 335 million years ago, but was perhaps not the first or only continental form. Likely, this continental formation was created from the coming together of other continents and land masses on Earth. This can be assumed in part due to the fact that continents and tectonic plates - large plates of the Earth’s crust that make up the surface of our planet - are constantly in motion, drifting apart or butting together. This process is continually happening, it just occurs at such a slow rate by human terms, that we do not see any significant shifts in a human lifetime, or even in the history of humans in general.
Proof Of A Single Landmass
While the creation and later separation of Pangea is of course, speculative, as humans did not exist at this time, there is a great deal of evidence to back these theories. Scientists' deeper understanding of plate tectonics have helped to specify movements and patterns in the Earth’s crust in a way in which previous theories of ‘Continental Drift’ could not. The formation and evidence of mountain ranges, rift valleys, and volcanic activity around plate borders and fault lines has greatly contributed to scientists’ understanding of tectonic plate movement and drift. These natural phenomena and geographical features indicate the deeper movements below the Earth’s crust, which can be tracked and traced to piece together a historical picture of how the continents have moved, in which ways the crust has broken and reformed, and the drifts and shifts that have occurred over time. Further, there is evidence which backs the idea that all continents were once one megacontinent, ie Pangea. This is seen primarily in fossil records of both flora and fauna found all over the globe. A variety of fossils have been found of similar or identical animal species across a variety of continents which are now great distances apart. This suggests that, like the Pangea theory outlines, these land masses once touched, allowing for free movement of species between now-continents. These fossils are often grouped along country or continent edges which were once joined with other continents. For example, the Eastern coast of Brazil and Western edge of Africa share fossils of the same type of reptile, indicating that these two land masses were once one, and the creatures lived in an area which later split in two.
The Separation Of Pangea
The Pangea landmass is estimated to have begun breaking apart roughly 175 million years ago. This break and splitting of the singular landmass occurred slowly and in segments, as rifts and fissures began to appear within the continent. These fissures and rifts were primarily caused by volcanic activity in the Earth’s mantle, the semi-liquid layer just below the crust. In this layer, heat a pressure build up below the Earth’s plates, until the force is too much to hold, and the magma - or liquid molten rock - breaks forth or causes rifts. When this happens, breaks and fissures begin to split the Earth apart, and push landmasses away from one another. This is an ongoing process, and can be seen even today along fault lines and plate borders where there is increased activity beneath the crust. It is this movement and pressure that causes major changes in the geographical landscape of the Earth, from volcanoes to mountain range formations, and even the movement of continents. This separation, once called ‘continental drift’ can be explained in terms of plate tectonics. These plates are large pieces of the Earth’s crust - also known as the lithosphere - which fit together like loose puzzle pieces. The difference lies in the fact that these pieces are not stationary, and in fact float, or move upon an underlying layer of semi-molten rock. This magma allows the plates to shift, move, and collide - albeit very slowly over great periods of time. The movements of the plates occur primarily along oceanic ridges, subduction zones and fault lines, meaning the plates are constantly in motion. This activity below the Earth’s surface was also the cause of Pangea’s break up. Understanding plate tectonics helped to hypothesize that the plates, and Pangea at large, did not come apart all at once, but rather broke, fractured, and separated slowly and in stages. This separation occurred in three major phases, and took place along distinct rifts.
As indicated, the first main phase, estimated to have been 180 million years ago, saw the creation of what we now know to be the central Atlantic Ocean and the Indian Ocean. The rift began in the Tethys Ocean running Westward to the Pacific. Cracking and fissures within the crust created multiple failed rifts along this line, resulting in the creation of the North Atlantic Ocean as North America began to split from Africa. Later, rifting occurred to the south, as the supercontinent known as Laurasia - (what we now know to be North America, Europe and Asia) drifted northward and rotated, resulting in the South Atlantic.
The area along Africa’s eastern coast also experienced a great deal of rifting. At the time, Antarctica and Madagascar were joined to Africa along the coast. As these rifts began to form, continents began to drift, and the Indian Ocean was created.
Phase two of Pangea’s separation occurred roughly 150 million years ago. At this point, the Earth consisted of Laurasia - North America, Europe and Asia - and Gondwana, which was Africa, South America,India, Antarctica and Australia. This phase primarily concerned Gondwana, and began the separation of these individual continents from their former landmass body. A subduction, or dropping in the Earth’s crust along the Tethyan trench, is thought to be the primary cause of Africa, India and Australia’s first big shifts northward, thus creating the South Indian Ocean. Later, a landmass dubbed Atlantica - current day Africa and South America - broke from Gondawana creating the South Atlantic Ocean, and over time this land mass drifted westward.
The Indian Ocean was also born at this time, as Madagascar and India disengaged from Antarctica and were pushed further north. India was still only just adrift of Africa at this time, and still connected to the island of Madagascar. A rift began to form within this land mass, and it eventually broke India and Madagascar apart. India was propelled away from its original African anchor, all the way up into Eurasia, further closing the Tethys Ocean. India collided with Eurasia approximately 50 million years ago, and it was this forceful collision that was the cause of the Himilayan mountains, which show the buckling and jarring of the Earth's crust along the plate lines there.
To the east, smaller fractures began to separate New Zealand, and New Caledonia from Australia proper. Thus, the Coral Sea and the Tasman Sea were born, as well as a number of cracks and smaller rifts where much volcanic activity still occurs.
The third phase of Pangea’s break up is what led, in a general sense, to the map of the Earth as we know it. Of course the tectonic plates are constantly in motion, but because this change is slight, the results of phase three are much the same as the position of the continents now.
This phase saw the remainder of the ‘multi-continent’ land masses breaking up and shifting positions. In the north, Laurasia split apart into Laurentia (North America and Greenland) and Eurasia. This resulted in another sea, known as the Norwegian, and occurred roughly 50 million years ago. Australia also fully separated from Antarctica at this time, and was pushed northward. The continent has been steadily shifting north ever since, and is expected to eventually collide with eastern Asia.
At the same time, South America shifted upward to the north, pulling apart from Antarctica. Smaller changes could be seen at this time as well, including the widening of the Gulf of California, the formation of the Alps, and fissures and rifts in the east, bringing Japan and the sea of Japan.
By fitting the continents back together jig-saw like, it is easy to see where the fractures and rifts tore the once singular continent of Pangea into its various parts, which drifted, rotated and reconnected over time.