What Is Pangea?
Approximately 335 million years ago, the Earth did not have seven continents but instead, it comprised of one massive supercontinent known as Pangea (or less commonly, Pangaea). Pangea existed during the late Paleozoic and early Mesozoic eras. Pangea was encompassed by a single ocean known as Panthalassa. About 175 million years ago, Pangea started to break apart resulting in the present continental mass distribution on Earth that we know today.
The term Pangea or Pangaea is derived from the Greek mythology Gaia and Ancient Greek. Alfred Wegener, a German meteorologist and geophysicist, was the first person who proposed the concept that the continents on Earth once existed as a continuous land mass. He also came up with the continental drift theory when he published "The Origin of Continents" in 1912. Later on, Wegener expanded his theory in another book he published called the "The Origin of Continents and Oceans". It was here in 1915 when he hypothesized that before the continental drift, the continents existed as a single supercontinent of which he named Urkontinent. The term Pangea first entered the English and German scientific literature in 1926 and 1922 respectively.
The History Of Supercontinents
Contrary to popular misconception, Pangea was not the first supercontinent in existence. The formation and drifting of supercontinents are believed to have been cyclical throughout the history of the Earth. Many other supercontinents had existed before Pangea. Nuna, which is also known as Columbia, seemed to have assembled in the era between 2.0 to 1.8 Ga. Nuna/Columbia broke apart forming the next supercontinent, known as Rodinia, from the assembly and the accretion of tectonic plates. The supercontinent last anywhere from 750 million years ago to approximately 1.1 billion years ago. However, the geodynamic history of Rodinia is not as well known or well understood as the supercontinents that were formed later like Pangea and Pannotia.
The Formation Of Pangea
The first step of the formation of Pangea took place when the ancient supercontinent of Gondwana started to slowly drift towards the South Pole. Step two of the formation of Pangea happened when Gondwana collided with Euramerica which had already been formed by the collision of Laurentia and Baltica by 440 Ma the Silurian time. During this time, Laurentia had not yet collided with Avalonia, which was slowly inching as the Lapetus Ocean continued to shrink. Concurrently the southern region of present-day Europe was breaking off from Gondwana and moving towards Euramerica across the newly-formed ocean. As time went by ,more countries such as North and South China, split from Gondwana heading northward. Oceans shrank while new ones were formed as a result of the drift and individual continents were created as a result.
Evidence Of The Existence Of Pangea
There is some evidence that support the theory of the existence of Pangea as a supercontinent such as fossil evidence which includes the presence of identical and similar species on a different continent that is currently thousands of miles apart. Other shreds of evidence include the geological trends of adjacent continents such as Africa and South America in the form of glacial deposits which is of the same structure and size. Palaeomagnetic study together with the continuity of chain of mountains also helps solidify the existence of Pangea.