Pangea is considered a fact, well-supported by scientific evidence, although the specific details of its configuration and breakup continue to be refined through ongoing research (which involves theoretical models).
Understanding the Distinction: Fact vs. Theory
It's important to understand the difference between a scientific fact and a scientific theory:
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Fact: An observation that has been repeatedly confirmed and for all practical purposes is accepted as "true." Truth in science, however, is never final and what is accepted as a fact today may be modified or even discarded tomorrow.
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Theory: A well-substantiated explanation of some aspect of the natural world that can incorporate facts, laws, inferences, and tested hypotheses. Theories are not mere guesses; they are robust explanations supported by a large body of evidence.
Evidence Supporting Pangea: A Brief Overview
The existence of Pangea is supported by a variety of evidence:
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Continental Fit: The shapes of continents, like South America and Africa, appear to fit together like puzzle pieces. This was one of the earliest observations that suggested continental drift, a precursor to plate tectonics.
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Fossil Distribution: Identical fossil species have been found on different continents that are now separated by vast oceans. This suggests that these continents were once joined together, allowing these species to roam freely across the landmass. Examples include the Mesosaurus fossil found in both South America and Africa.
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Geological Structures: Mountain ranges and rock formations on different continents align and match up when the continents are brought together. For example, the Appalachian Mountains in North America are geologically similar to mountain ranges in Scotland and Norway.
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Paleoclimatic Data: Evidence of past climates, such as glacial deposits and coal beds, indicate that continents were once located in different latitudes than they are today. For instance, glacial deposits found in present-day Africa and India suggest that these regions were once located near the South Pole.
Pangea in the Context of Plate Tectonics
Pangea's existence is explained by the theory of plate tectonics. Plate tectonics is the scientific theory explaining the large-scale motions of Earth's lithosphere. The lithosphere, which is the rigid outermost shell of a planet (the crust and upper mantle), is broken up into tectonic plates. The relative movement of these plates explains many geological phenomena, including continental drift, earthquakes, volcanic activity, and mountain building.
The breakup of Pangea, which started about 200 million years ago, is a direct consequence of plate tectonic processes. The supercontinent fragmented, and the resulting continents drifted to their current positions.
Pangea and Prior Supercontinents
Geologists have found evidence suggesting that Pangea was not the only supercontinent to exist. Other supercontinents, such as Rodinia (approximately 1 billion years ago) and Pannotia (approximately 600 million years ago), likely existed before Pangea. The cycle of supercontinent formation and breakup appears to be a recurring process throughout Earth's history.
