What is the continental crust made of?

Continental crust is the layer of igneous, metamorphic, and sedimentary rocks that forms the geological continents and shallow continental shelves. It has a lower density and is richer in aluminium silicates compared to oceanic crust, earning it the historical name sial. Seismic velocities reveal a sharp contrast, known as the Conrad discontinuity, separating its more felsic upper section from its more mafic lower section, while the entire crust sits above the denser mantle.

What we know

• Continental crust is composed of igneous, metamorphic, and sedimentary rocks forming geological continents and shallow shelves. [2]
• The continental crust is also called sial because its bulk composition is richer in aluminium silicates and has lower density than oceanic crust. [2]
• Changes in seismic wave velocities indicate a contrast called the Conrad discontinuity between the upper and lower continental crust. [2]
• Most continental crust sits as dry land above sea level, although major regions like Zealandia can be predominantly submerged, and the crust itself forms the top component of the lithosphere resting atop the denser mantle. [2, 3]

Where to go next

• compared withHow does oceanic crust differ from continental crust?
• how we knowWhat is the Mohorovičić discontinuity?
• how it workedHow do tectonic plates move across the Earth?
• the bigger pictureWhat is the Earth's lithosphere?
• a case in pointHow much of the Zealandia crust is submerged underwater?
• an unexpected connectionHow does radioactive decay drive the movement of continents?Radioactive decay deep inside the Earth powers mantle convection, which in turn drives the movement of lithospheric plates and continental crust across the globe.

Sources

• [1]continental crust (Wikidata Q858571) · CC0 1.0
• [2]Continental crust · CC BY-SA 4.0
• [3]Earth's crust · CC BY-SA 4.0
• [4]Continental drift · CC BY-SA 4.0
• [5]Abundance of elements in Earth's crust · CC BY-SA 4.0