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The supercontinent cycle sees the Earth’s continents merge and split every 300-500 million years due to tectonic plate movement. Previous supercontinents include Pangea and Gondwanaland, and the cycle affects Earth’s climate and coastlines.
The supercontinent cycle is a geological cycle in which the Earth’s continents alternately merge into a single supercontinent, split into numerous continents, then merge again. The cycle is estimated at 300 – 500 million years. The supercontinent cycle is simply the result of geometry; given that approximately 29% of the earth’s surface is composed of continents resting on tectonic plates that move approximately randomly, after a certain period of time, these continents will eventually aggregate and stick together. But they won’t stay forever: Fracture events between the continental plates cause them to drift apart again, and the supercontinent cycle continues.
Previous supercontinents have included Pangea, which formed 250 million years ago, Gondwanaland, which formed about 600 million years ago, Rodinia, which existed ~1.1 billion to ~750 million years ago, Columbia, which existed ~1.8 to 1.5 billion years ago., Kenorland, which existed about 2.7 to about 2.1 billion years ago, Ur, which existed about 3 billion years ago, and Vaalbara, which existed about 3.6 to about 2.8 billion years ago of years ago. Prior to this, the Earth didn’t have much continental crust and thus no supercontinental cycles.
Earth’s climate can be markedly different depending on where the Earth’s landmasses are located in the supercontinent cycle and where they are on the Earth’s surface. For example, when a continent is frozen around a pole, as is the case in Antarctica, a continental ice sheet can grow which significantly lowers temperatures around the pole. Cold water absorbs heat from equatorial currents, lowering temperatures worldwide.
In general, the coasts of the world tend to be wetter and therefore more life-friendly places. When the world’s landmasses are in the supercontinent phase of the supercontinent cycle, the world’s shorelines are diminished and the center of the supercontinent turns into a vast desert. About 250 million years ago, at the dawn of the Mesozoic, the center of the continent Pangea was a vast desert, crossed by the few tetrapod vertebrates that survived the Permian-Triassic extinction before it.
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