The key differences between oceanic and continental crust lie in their composition, density, buoyancy, thickness, and age.
Composition and Density
- Oceanic Crust: Primarily composed of basalt, a dark, dense volcanic rock. This composition gives it a greater density compared to continental crust.
- Continental Crust: Largely made of granite, a less dense rock. This makes the continental crust less dense.
Buoyancy
Because of the differences in density:
- Oceanic crust has lower buoyancy; therefore, it sits lower within the Earth's mantle.
- Continental crust exhibits higher buoyancy; therefore, it floats higher within the mantle.
Thickness and Age
- Oceanic crust is typically much thinner than continental crust.
- Continental crust is considerably thicker.
- Oceanic crust is relatively younger. It is constantly being created at mid-ocean ridges and destroyed at subduction zones, resulting in a geologically short lifespan.
- Continental crust is much older, with some portions dating back billions of years.
Summary Table
| Feature | Oceanic Crust | Continental Crust |
|---|---|---|
| Composition | Basalt | Granite |
| Density | Higher | Lower |
| Buoyancy | Lower | Higher |
| Thickness | Thinner | Thicker |
| Age | Younger | Older |
In summary, the oceanic crust, made of dense basalt, is thinner and younger, while the continental crust, composed of less dense granite, is thicker and older. This difference in density influences their buoyancy and their relative positions on the Earth's surface.
