Composition:
* Continental Crust: Composed primarily of felsic (rich in silica) rocks like granite, with lesser amounts of mafic (rich in magnesium and iron) rocks like basalt. It's thicker, less dense, and older.
* Oceanic Crust: Primarily composed of mafic rocks like basalt and gabbro. It's thinner, denser, and younger.
Thickness:
* Continental Crust: Ranges from 30 to 70 km (19 to 43 miles) thick.
* Oceanic Crust: Ranges from 5 to 10 km (3 to 6 miles) thick.
Density:
* Continental Crust: Less dense (about 2.7 g/cm3).
* Oceanic Crust: Denser (about 3.0 g/cm3).
Age:
* Continental Crust: Much older, with some parts dating back billions of years.
* Oceanic Crust: Continuously being created at mid-ocean ridges and destroyed at subduction zones, making it relatively young (generally less than 200 million years old).
Features:
* Continental Crust: Characterized by mountains, plateaus, plains, and valleys. It hosts various landforms and is home to most of Earth's biosphere.
* Oceanic Crust: Forms the ocean floor, featuring mid-ocean ridges, trenches, and abyssal plains.
Formation:
* Continental Crust: Formed over millions of years through a complex process involving volcanic activity, tectonic collisions, and the recycling of older crust.
* Oceanic Crust: Created at mid-ocean ridges where magma rises from the mantle and solidifies.
Subduction:
* Continental Crust: Less dense, so it tends to float on top of the denser oceanic crust. This is why continental crust is typically older and less likely to be subducted.
* Oceanic Crust: More dense, so it is subducted beneath both continental and oceanic crust at convergent plate boundaries.
In summary:
Continental crust is older, thicker, less dense, and composed of felsic rocks, while oceanic crust is younger, thinner, denser, and composed of mafic rocks. These differences have significant implications for Earth's geology, including the formation of continents, oceans, mountains, and the distribution of Earth's resources.
