Which crust forms the ocean floors?

Which crust forms the ocean floors?

• A. Ocean
• B. Continental
• C. Mantle
• D. Core

Answer: (A)

Different crust types make up Earth's surface, and the ocean floors are formed specifically by oceanic crust. Oceanic crust is the part that underlies the oceans; it is relatively thin—only about 5 to 10 kilometers thick—and mainly composed of basalt. It forms at mid-ocean ridges where magma rises and cools to create new crust, which then spreads away from the ridge and becomes the seafloor. Because oceanic crust is denser than continental crust, it sits beneath the ocean water and forms the actual floor of the ocean. Continental crust, by contrast, is thicker, less dense, and makes up the continents, not the sea floor. The mantle lies beneath the crust, and the core is the Earth's center. Therefore, the layer that forms the ocean floors is oceanic crust.

Different crust types make up Earth's surface, and the ocean floors are formed specifically by oceanic crust. Oceanic crust is the part that underlies the oceans; it is relatively thin—only about 5 to 10 kilometers thick—and mainly composed of basalt. It forms at mid-ocean ridges where magma rises and cools to create new crust, which then spreads away from the ridge and becomes the seafloor. Because oceanic crust is denser than continental crust, it sits beneath the ocean water and forms the actual floor of the ocean. Continental crust, by contrast, is thicker, less dense, and makes up the continents, not the sea floor. The mantle lies beneath the crust, and the core is the Earth's center. Therefore, the layer that forms the ocean floors is oceanic crust.