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The positions of continents have been accurately determined back to the early Jurassic, shortly before the breakup of Pangaea. [6] Pangaea's predecessor Gondwana is not considered a supercontinent under the first definition since the landmasses of Baltica, Laurentia and Siberia were separate at the time. [7]
Map of Pangaea with modern continental outlines. The supercontinent cycle is the quasi-periodic aggregation and dispersal of Earth's continental crust.There are varying opinions as to whether the amount of continental crust is increasing, decreasing, or staying about the same, but it is agreed that the Earth's crust is constantly being reconfigured.
By the time Pangaea broke up, in the Middle Jurassic, the seas swarmed with molluscs (particularly ammonites), [41] ichthyosaurs, sharks and rays, and the first ray-finned bony fishes, while life on land was dominated by forests of cycads and conifers in which dinosaurs flourished and in which the first true mammals had appeared.
A continent is a large geographical region defined by the continental shelves and the cultures on the continent. [1] In the modern day, there are seven continents. However, there have been more continents throughout history. Vaalbara was the first supercontinent. [2] Europe is the newest continent. [3]
Gondwana (/ ɡ ɒ n d ˈ w ɑː n ə /) [1] was a large landmass, sometimes referred to as a supercontinent.The remnants of Gondwana make up around two-thirds of today's continental area, including South America, Africa, Antarctica, Australia, Zealandia, Arabia, and the Indian subcontinent.
This cycle is most likely caused by the break-up and formation of super-continents. The earth went through major climatic swings over the course of 200 to 400 million years. From the late Pre-Cambrian to the late Cambrian , late Devonian to the Triassic - Jurassic border, and since the Miocene until the present time, the earth was an "icehouse ...
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The degree of certainty to which the identified landmasses can be regarded as independent entities reduces as geologists look further back in time. The list includes cratons, supercratons, microcontinents, continents and supercontinents. For the Archean to Paleoproterozoic cores of most of the continents see also list of shields and cratons.