Continental Drift
Continental drift is the hypothesis that Earth's continents were once joined together in a single supercontinent called Pangaea and have since moved apart over geological time to their current positions. Proposed by Alfred Wegener in 1912, the hypothesis was supported by the jigsaw-fit of continents, matching fossil records across oceans, and similar rock formations on different continents. Continental drift later became a cornerstone of plate tectonic theory, which provided the mechanism of seafloor spreading to explain how continents move.
Evidence Supporting Continental Drift
| Evidence Type | Description | Continents Involved |
|---|---|---|
| Geometric Fit | Coastlines of Africa and South America align like puzzle pieces | Africa, South America |
| Fossil Match | Mesosaurus fossils found only in South America and Africa | Africa, South America |
| Rock Correlation | Identical rock sequences in Scotland and Newfoundland | Europe, North America |
| Glacial Striations | Ice age scratch marks indicate past polar positions in tropics | India, Africa, Australia |
| Climate Fossils | Tropical plant fossils found in Antarctica | Antarctica |
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Related Terms
Plate Tectonics
Plate tectonics is the scientific theory describing how Earth's lithosphere is divided into large, rigid segments called tectonic plates that move over the underlying asthenosphere. These plates interact at their boundaries through convergence, divergence, or lateral sliding, driving processes such as mountain building, ocean floor spreading, and volcanic activity. The theory unifies many geological phenomena and explains the distribution of earthquakes, volcanoes, and major landforms across Earth's surface.
Rock Cycle
The rock cycle is a continuous geological process by which rocks are transformed from one type to another through processes such as melting, cooling, erosion, deposition, compaction, cementation, heat, and pressure over geological timescales. The three main rock types — igneous, sedimentary, and metamorphic — are interconnected in this cycle, each capable of being converted into another type under the right conditions. Understanding the rock cycle helps geologists interpret Earth's history, locate mineral resources, and predict geological hazards.
Sedimentary Rock
Sedimentary rock is formed from the accumulation and compaction of sediments — particles of minerals, organic matter, or chemical precipitates — deposited by water, wind, ice, or gravity over time. This process, called lithification, involves compaction (pressure from overlying sediment) and cementation (mineral-rich groundwater binding particles together). Sedimentary rocks cover about 75% of Earth's land surface, host nearly all fossil records, and contain major reserves of coal, oil, natural gas, and economically important minerals.
From Latin "continens" (continuous landmass) and Middle English "driften" (to float or be carried). Alfred Wegener used the German term "Kontinentalverschiebung" (continental displacement) in 1912; the English phrase "continental drift" became standard in geological literature by the 1920s.