Continental crust

Definition

Continental crust is the thick, less dense portion of the Earth's crust that forms the continents and continental shelves. It is primarily composed of granitic rocks and is significantly older and thicker compared to oceanic crust, playing a key role in processes such as continental collision and mountain building.

5 Must Know Facts For Your Next Test

1. The continental crust can reach thicknesses of up to 70 kilometers, especially in mountain ranges like the Himalayas.
2. Continental crust is generally composed of lighter materials compared to oceanic crust, which contributes to its higher elevation above sea level.
3. The formation of continental crust occurs over billions of years through processes such as volcanic activity, sedimentation, and tectonic movements.
4. When two continental plates collide, neither plate is subducted; instead, they crumple and fold, leading to the creation of mountain ranges.
5. Continental crust is less susceptible to recycling than oceanic crust, meaning it can preserve geological history much longer.

Review Questions

• How does the composition of continental crust differ from oceanic crust, and what implications does this have for geological features?
  • Continental crust is primarily composed of lighter granitic rocks, while oceanic crust is made up of denser basaltic rocks. This difference in composition leads to variations in elevation; continental crust generally exists at higher altitudes than oceanic crust. Additionally, the lower density of continental crust contributes to its stability and longevity, allowing it to support features like mountains when tectonic plates collide rather than being recycled into the mantle.
• Discuss the role of continental collision in mountain building processes and provide an example.
  • Continental collision plays a crucial role in mountain building as it causes two continental plates to push against each other. This results in significant geological activity where neither plate is subducted due to their similar densities; instead, they crumple and fold. An example of this process is the formation of the Himalayas, where the Indian Plate collided with the Eurasian Plate, creating one of the tallest mountain ranges on Earth.
• Evaluate the impact of continental crust on Earth's geology over geological time scales, including its relationship with tectonic activity.
  • Continental crust has a significant impact on Earth's geology over time due to its stability and longevity compared to oceanic crust. Its formation and preservation allow for the accumulation of diverse geological history, including fossil records. The interaction of tectonic plates at their boundaries affects not only the formation of mountains but also triggers earthquakes and volcanic activities. By influencing these geological processes, continental crust contributes to shaping Earth’s landscapes and ecosystems throughout its long history.

Related terms

Oceanic crust: The thinner, denser part of the Earth's crust that lies beneath the ocean basins, primarily composed of basaltic rocks.

Subduction:

The process by which one tectonic plate moves under another plate and sinks into the mantle, often leading to volcanic activity and mountain building.

Tectonic plates: Massive slabs of the Earth's lithosphere that move and interact with each other at their boundaries, causing geological activities like earthquakes and mountain formation.