Supercontinents are continents that include multiple cratons, with Pangea being an example that encompassed almost all land on Earth. Seafloor spreading causes continents to come together and form a supercontinent, which eventually splits again in a cycle that repeats every 250 to 500 million years. A future supercontinent, Pangea Ultima, has been tentatively named. Supercontinents are hostile to life due to extreme temperatures and vast deserts in their interiors.
A supercontinent is a continent that includes more than one craton (continental core). A modern example is Eurasia. This example may be misleading, however, because virtually every modern continent has numerous minor cratons. Here, the word “craton” generally refers to historical continents, such as Baltica, the craton under Europe, which has been an independent continent in the geological past.
Another definition sometimes used for supercontinent is narrower: a continent that makes up most of the land on Earth. The prototypical example would be Pangea, a C-shaped landmass that existed 250 million years ago, encompassing almost all land on Earth, with the exception of northern China and a few smaller islands. Pangea straddled the equator, almost reaching from Pole to Pole. Pangea was centered on today’s Atlantic Ocean. In fact, the Mid-Atlantic Ridge in the Atlantic Ocean is the original rift that caused Pangea to split.
Supercontinents are the culmination of an effect called seafloor spreading, in which fissures in the center of seafloors around the world continue to generate new crust, pushing continents along with them. This seafloor spreading eventually pushes all the world’s continents together (because some rift systems will always prevail over others), forming a supercontinent. Within 20-100 million years, the supercontinent splits again. This process is called the supercontinent cycle and is thought to repeat every 250 to 500 million years. A possible future supercontinent has tentatively been named Pangea Ultima.
A supercontinent is relatively hostile to life. Its interior is vast deserts with extreme temperatures. This is due to the absence of the thermal modulation effects of water and the fact that the continent is so large that it is difficult for clouds to float to the center and drop their payloads. Imagining a continent three times the size of Eurasia gives new meaning to the term ‘landlocked country’.
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