Here's a breakdown:
* Earth's Structure: The Earth's outermost layer, called the lithosphere, is broken into large, rigid pieces called tectonic plates. These plates "float" on a semi-molten layer called the asthenosphere.
* Convection Currents: Heat from Earth's core creates convection currents within the asthenosphere. Hotter, less dense material rises, while cooler, denser material sinks.
* Plate Movement: These convection currents drag the tectonic plates along with them, causing them to move slowly across the Earth's surface.
* Types of Plate Boundaries:
* Divergent boundaries: Plates move apart, creating new crust (e.g., mid-ocean ridges).
* Convergent boundaries: Plates collide, causing mountains, volcanoes, and earthquakes (e.g., the Himalayas, the Andes).
* Transform boundaries: Plates slide past each other horizontally, causing earthquakes (e.g., the San Andreas Fault).
Key Concepts:
* Continental Drift: The idea that continents move over time, proposed by Alfred Wegener in the early 20th century. Plate tectonics is the modern, more comprehensive explanation of this phenomenon.
* Seafloor Spreading: The process of new ocean floor being created at mid-ocean ridges.
* Subduction: When one tectonic plate slides beneath another.
Plate tectonics is a fundamental theory in geology, explaining a wide range of geological phenomena, including earthquakes, volcanoes, mountain formation, and the distribution of continents and oceans.
