Continental Crust
* Thickness: 35-70 km (22-43 miles)
* Density: 2.7 g/cm³
* Composition: Mostly granite, with significant amounts of sedimentary and metamorphic rocks
* Age: Ranges from very old (billions of years) to relatively young
Oceanic Crust
* Thickness: 5-10 km (3-6 miles)
* Density: 3.0 g/cm³
* Composition: Primarily basalt and gabbro
* Age: Relatively young, generally less than 200 million years old
Why the difference in height?
* Density: Oceanic crust is denser than continental crust due to its composition (basalt vs. granite). This means it sits lower in the mantle.
* Thickness: Continental crust is thicker, meaning it "floats" higher on the mantle.
How this affects the Earth's surface:
* Mountains: Continental crust's thickness and buoyancy are responsible for the formation of high mountain ranges.
* Ocean basins: The denser oceanic crust sits lower, forming the ocean basins.
* Continental shelves: The shallower areas around continents are part of the continental crust that extends under the ocean.
In summary: The difference in density and thickness between continental and oceanic crust leads to a significant height difference. This is a fundamental factor in shaping the Earth's surface.