티스토리 뷰
Introduction
Plate tectonics refers to the scientific theory that explains the movement and interactions of Earth's lithospheric plates. The lithosphere, which is composed of the rigid outer layer of the Earth, is divided into several large and small plates that float on the semi-fluid asthenosphere beneath. These plates are constantly moving, albeit at a very slow pace, and their interactions at their boundaries give rise to various geological phenomena such as earthquakes, volcanic eruptions, and the creation of mountain ranges.
Continental Drift
One of the key aspects of plate tectonics is the concept of continental drift. This theory, proposed by Alfred Wegener in the early 20th century, suggested that the Earth's continents were once a single supercontinent called Pangaea, which later broke apart and drifted to their current positions. Wegener supported his hypothesis with geological evidence such as the jigsaw-like fit of the South American and African coastlines and the presence of similar fossils and rock formations on different continents.
However, it was not until the 1960s that technological advancements in Earth sciences, such as the development of mapping techniques and the discovery of magnetic anomalies on the ocean floor, provided concrete evidence for continental drift. These discoveries led to the acceptance of the theory of plate tectonics, which incorporated and expanded upon Wegener's ideas.
Divergent Boundaries
At divergent plate boundaries, two plates move away from each other. This movement creates a gap where molten rock or magma from the asthenosphere rises to the surface, leading to the formation of new crust. The upward movement of magma results in volcanic activity, giving birth to mid-oceanic ridges. Examples of divergent boundaries include the Mid-Atlantic Ridge and the East Pacific Rise.
Convergent Boundaries
Convergent plate boundaries occur when two plates collide or come together. There are three types of convergence: oceanic-oceanic, oceanic-continental, and continental-continental. In oceanic-oceanic convergence, one plate is forced beneath the other in a process called subduction. The subducted plate sinks into the mantle, creating deep-sea trenches and generating volcanic arcs. Oceanic-continental convergence involves the subduction of oceanic lithosphere beneath a continental plate, resulting in the formation of coastal mountain ranges and volcanic belts. Continental-continental convergence leads to the collision and uplift of large mountain ranges, such as the Himalayas.
Transform Boundaries
Transform boundaries occur when two plates slide past each other horizontally. This type of plate boundary is characterized by large faults, such as strike-slip faults, where the plates grind against each other in opposite directions. Transform boundaries are mainly responsible for creating earthquakes. The San Andreas Fault in California is a prime example of a transform boundary.
In conclusion, plate tectonics is a fundamental concept in understanding the Earth's dynamic nature. It explains the movement of continents, the formation of mountains and volcanoes, and the occurrence of earthquakes. By studying plate tectonics, scientists can gain insight into the geological processes that have shaped our planet over millions of years.