Astronomy

Pangea, the whole earth

Pangea, the whole earth

Through the study of the reliefs in the current emergent lands, their age and the type of fossils contained in the rocks, geologists have been able to know the evolution that the continents have experienced. Thus, about 1.1 billion years ago (m.a.) it is believed that all continents were unified in one called Rodinia, which fragmented about 750 m.a. to re-form a new megacontinent called Pannotia, about 600 m.a. And again it fragmented again 60 m.a. later.

The problem is that there are very few records of rocks of these ages that are emerged and sufficiently exposed to allow geological studies on them, which allow them to be compared and spatially determine the shape and position of the continents at that time.

In what there is greater agreement is to accept that the different continents that existed after the supposed break of Pannotia were approaching again to generate, about 300 m.a., a macrocontinent called Pangea or what is the same, "the whole earth" (translated from Greek).

The enormous immensity of the continent allowed infinity of species to develop and distribute - both on land and in the surrounding mega-ocean called Panthalassa or "all seas" - generating large forests that would result in almost all of the large concentrations of coal that are still being exploited.

This situation came to an end when the magma made its way to the surface creating a large fracture and the formation of a dorsal that marked the beginning of the fragmentation of the megacontinent, will be about 200 m.a. This separation brought about the disappearance of large groups of living beings towards the end of the Permian and early Triassic, assuming a change of era (from Paleozoic to Mesozoic).

Thus began the "age of the dinosaurs" or Mesozoic leading to a loss of almost 95% of living things that until then existed, in the greatest faunal extinction in history and still not very well understood, managing different causes to explain so massive species mortality.

From Pangea to today's world

In general, there are three main stages that led to the defragmentation of Pangea. The first, towards the beginning of the Jurassic, meant the appearance of a proto-ocean or Thetis, the future Atlantic Ocean. North America and Europe (being called Laurasia to this set of land located north of the proto-ocean) they separated from present-day Africa and the rest of America, which were attached to other plates (known as Gondwana).

The Thetis continued to grow, separating both land masses while the African plate separated within Gondwana, beginning to generate what would be the South Atlantic Ocean, in the Cretaceous. This caused the turn of Gondwana so that the north of the African plate approached Laurasia generating the closure of an area of ​​the Thetis that will later produce the Mediterranean Sea and Indian Ocean. On the other hand, the new mass of Gondwana that contained the African plate suffered fractures, detaching the Antarctic and Madagascar plates.

In this way you reach the second stage, along the Cretaceous, which will end the formation of South America, Africa, India and Antarctica + Australia. These separations continue to grow generating seas in progressive increase, while India moves from South Africa to its current position, separating the Mediterranean from the Indian Ocean.

In the third stage and new era change (the "age of mammals" began), Laurasia fragmented and the Atlantic increased in size, leading the continents to situations very close to the current ones. Even today, the Atlantic continues to expand so that there are those who believe that the emerging lands are in a slow drift towards a new megacontinent future.

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