Plate Tectonics Overview

Study Notes

Plate Tectonics

Plate tectonics is a theory that describes large-scale motions of Earth's lithosphere.
It explains the formation, movement, and interaction of Earth's plates.
The theory was developed after years of observing that continents appeared to move over time.

Types of Plate Boundaries

Divergent boundaries: Plates move apart, creating new crust. Magma rises to the surface, forming new oceanic crust. Examples include mid-ocean ridges.
Convergent boundaries: Plates collide, leading to subduction (one plate moving under another) or mountain building. Oceanic-continental convergence can create volcanoes. Oceanic-oceanic convergence creates volcanic island arcs. Continental-continental convergence builds mountain ranges.
Transform boundaries: Plates slide past each other horizontally, causing friction and earthquakes. Famous examples are the San Andreas Fault.

Theory of Continental Drift

Proposed by Alfred Wegener, this superseded theory posited that continents were once joined in a supercontinent called Pangaea.
Evidence supported the idea of continental drift as it detailed similar fossils, rock types, and geological structures on continents now separated, suggesting a past connection.

Convection Currents

These are slow, circulating movements of the mantle's semi-molten rock (magma/asthenosphere).
Driven by differences in temperature and density, hot material rises, cools, and sinks, creating a cyclical pattern.
This movement is considered a key driving force of plate tectonics.

Seafloor Spreading

This process occurs at mid-ocean ridges where new oceanic crust forms as magma rises to the surface and solidifies.
As new crust forms, older crust moves away from the ridge.
The age of the seafloor progressively gets older as you move further away from the mid-ocean ridge.
The mechanism for seafloor spreading is driven by convection currents in the mantle.

Interior of Earth

The Earth has progressively denser layers as you go from the outer crust to the inner core.
The crust is the outermost solid layer composed of different rock types.
The mantle is a thick, semi-molten layer of rock beneath the crust, crucial for convection.
The core is composed of iron and nickel, with a solid inner core and a liquid outer core. The liquid outer core generates Earth's magnetic field.
Each layer has distinct properties concerning composition, temperature, and pressure.

Description

Explore the fascinating theory of plate tectonics that details the movement and interaction of Earth's lithosphere. This quiz covers the different types of plate boundaries, such as divergent, convergent, and transform, along with the historical context of the continental drift theory proposed by Alfred Wegener.