The Chocolate Hills of the Philippines are an example of continental crust. More broadly, the continents themselves are composed of continental crust.
Understanding Continental Crust
Continental crust is the uppermost layer of Earth's lithosphere forming the continents and shallow seabed areas near coastlines (continental shelves). It's primarily made of less dense, granitic rocks (igneous, sedimentary, and metamorphic). This is in contrast to oceanic crust, which is denser and primarily basaltic.
Several examples illustrate continental crust formations and interactions:
- The Himalayas: Formed by the collision of the Indian and Eurasian plates, demonstrating a continent-continent convergent boundary where neither plate subducts.
- The Andes Mountains: Created by the subduction of the Nazca Plate (oceanic) under the South American Plate (continental), showcasing an ocean-continent convergent boundary.
The difference in density between oceanic and continental crust is crucial. Oceanic crust, being denser, subducts (slides beneath) continental crust when they converge. This process often leads to volcanic activity and mountain building. However, when two continental plates collide, neither subducts due to their similar buoyancy, resulting in the uplift of large mountain ranges like the Himalayas.
The key characteristic of continental crust is its lower density compared to oceanic crust, making it less likely to subduct. This difference in density and behavior during plate interactions is a cornerstone of plate tectonic theory.
