Understanding Continental Drift
Continental drift is a scientific theory proposed by Alfred Wegener in 1912, suggesting that Earth's continents have moved over geologic time relative to each other, appearing to "drift" across the ocean bed. This theory revolutionized geology by proposing that continents were not fixed but were dynamic entities moving across the planet.
Key Principles and Evidence
Wegener's theory was based on several pieces of evidence: the striking "fit" of continents (like South America and Africa), identical fossil records found on widely separated continents (e.g., the *Mesosaurus* reptile), similar rock types and mountain ranges across oceans, and paleoclimate data indicating ancient ice sheets in areas now near the equator.
A Practical Example: Gondwana
A prominent example supporting continental drift is the supercontinent Gondwana, which comprised present-day South America, Africa, Antarctica, Australia, and India. The discovery of the same plant and animal fossils, as well as distinct rock sequences, across these landmasses strongly suggested they were once connected before gradually separating.
Importance and Evolution of the Theory
Initially met with skepticism due to the lack of a known mechanism for continental movement, Wegener's theory laid the foundational groundwork for the more comprehensive theory of plate tectonics developed in the 1960s. It transformed our understanding of Earth's dynamic surface and remains a fundamental concept in geology today.