Continental crust

Definition

Continental crust is the thick part of the Earth's crust that forms the continents, consisting primarily of granitic rocks and varying in thickness from about 30 to 70 kilometers. It plays a vital role in plate tectonics, serving as a platform for geological processes such as mountain building and the formation of various landforms.

5 Must Know Facts For Your Next Test

1. Continental crust is generally older than oceanic crust, with some parts dating back over 4 billion years.
2. It is less dense than oceanic crust due to its composition of lighter granitic rocks compared to the heavier basaltic rocks of oceanic crust.
3. Continental crust can be significantly deformed during tectonic events, leading to the formation of mountain ranges and rift valleys.
4. The thickness of continental crust varies widely, with thicker areas typically found at mountain ranges and thinner areas located beneath plains.
5. Continental crust plays a key role in hosting mineral resources and is essential for human activities such as agriculture and urban development.

Review Questions

• How does continental crust differ from oceanic crust in terms of composition and density?
  • Continental crust is primarily composed of granitic rocks, making it less dense than oceanic crust, which is mainly composed of basaltic rocks. This difference in composition affects their buoyancy; continental crust floats higher on the mantle compared to oceanic crust. Additionally, continental crust is thicker, ranging from 30 to 70 kilometers, while oceanic crust typically has a thickness of about 5 to 10 kilometers.
• Discuss the importance of continental crust in the process of plate tectonics and its impact on geological features.
  • Continental crust is crucial in plate tectonics because it interacts with other tectonic plates during movements. When tectonic plates converge, it can lead to mountain building or the uplift of landmasses, creating significant geological features. Conversely, when plates diverge, it may lead to rifting or the formation of new basins. The dynamic nature of continental crust contributes to the constantly changing landscape of our planet.
• Evaluate how isostasy influences the stability and elevation of continental crust in relation to surrounding geological processes.
  • Isostasy refers to the equilibrium between the continental crust and the denser mantle beneath it, affecting how landmasses respond to geological forces. When mountains erode over time, their weight decreases, leading to a rise in elevation due to isostatic rebound. Conversely, when ice sheets melt or sediment accumulates on a continent, this can lead to subsidence. Understanding isostasy helps explain the balance between forces acting on continental crust and its elevation changes over geological timescales.

Related terms

oceanic crust:

The thinner, denser part of the Earth's crust that underlies the oceans, primarily composed of basaltic rocks.

plate tectonics:

The scientific theory that describes the large-scale movement of Earth's lithosphere, which is divided into tectonic plates that float on the semi-fluid asthenosphere.

isostasy: The equilibrium between continental crust and the denser mantle below it, explaining how landmasses rise or sink based on their weight and the support they receive.