puste-ye qâre-yi (#)
Fr.: croûte continentale
The part of the → Earth's crust which underlies the → continents. Continental crust is more silica-rich and thicker than → oceanic crust, and is on average older. However, it is highly variable in all of these respects. The average thickness of the continental crust is about 40km, but beneath parts of the Andes and the Himalaya mountain ranges the crust is more than 70 km thick. Continental crust is continuously being eroded and turned into sediment. Some of this sediment ends up on the ocean floor where it can be returned to the → Earth's mantle at → subduction zones. The oldest parts of the continental crust include some rocks that are nearly 4 billion years old. New continental crust is produced by the destruction of oceanic crust at subduction zones, a process that continues today.