Seafloor Spreading

Definition

Seafloor spreading is a geological process in which new oceanic crust is formed by the upwelling and cooling of molten magma from the Earth's mantle at mid-ocean ridges. This process is a key component of plate tectonics and the continuous renewal of the Earth's surface.

5 Must Know Facts For Your Next Test

1. Seafloor spreading occurs at mid-ocean ridges, where two tectonic plates move apart, allowing magma to rise and new oceanic crust to be formed.
2. The newly formed oceanic crust gradually moves away from the mid-ocean ridge, creating a conveyor belt-like motion that continuously renews the Earth's surface.
3. As the oceanic crust moves away from the mid-ocean ridge, it cools and becomes denser, eventually sinking back into the Earth's mantle at deep-sea trenches, a process known as subduction.
4. The age of the seafloor increases with distance from the mid-ocean ridge, with the oldest oceanic crust found near the deep-sea trenches.
5. Seafloor spreading is a key driver of plate tectonics, as the movement of the plates is powered by the continuous creation and destruction of the Earth's surface.

Review Questions

• Explain how seafloor spreading is connected to the concept of plate tectonics.
  • Seafloor spreading is a fundamental process of plate tectonics, as it is the mechanism by which new oceanic crust is continuously formed at mid-ocean ridges. The upwelling and cooling of molten magma from the Earth's mantle creates new crust, which then moves away from the ridge, forming a conveyor belt-like motion that drives the movement of tectonic plates. This plate movement, in turn, leads to the formation of other plate tectonic features, such as deep-sea trenches and volcanoes, making seafloor spreading a crucial component of the overall plate tectonic system.
• Describe the relationship between seafloor spreading and the age of the oceanic crust.
  • The age of the oceanic crust is directly related to the process of seafloor spreading. As new crust is formed at mid-ocean ridges, it gradually moves away from the ridge, with the oldest crust found near deep-sea trenches where it is subducted back into the Earth's mantle. This means that the age of the oceanic crust increases with distance from the mid-ocean ridge, with the youngest crust located closest to the ridge and the oldest crust found furthest away. This age distribution of the oceanic crust is a key piece of evidence supporting the theory of plate tectonics and the continuous renewal of the Earth's surface through the process of seafloor spreading.
• Analyze how the process of seafloor spreading contributes to the continuous renewal of the Earth's surface.
  • The process of seafloor spreading is a fundamental driver of the continuous renewal of the Earth's surface. At mid-ocean ridges, where tectonic plates move apart, new oceanic crust is formed by the upwelling and cooling of molten magma from the Earth's mantle. This newly formed crust then gradually moves away from the ridge, creating a conveyor belt-like motion that constantly replenishes the ocean floor. As the crust moves away, it cools and becomes denser, eventually sinking back into the Earth's mantle at deep-sea trenches through a process called subduction. This continuous cycle of crust formation at mid-ocean ridges and destruction at deep-sea trenches is a key mechanism by which the Earth's surface is continuously renewed, with older crust being replaced by newer crust over geological timescales. This dynamic process is a central tenet of plate tectonics and is essential for maintaining the habitable conditions on our planet.

Related terms

Mid-Ocean Ridge: An underwater mountain range formed by the upwelling of molten rock from the Earth's mantle, where tectonic plates move apart, allowing new crust to be formed.

Plate Tectonics:

The theory that the Earth's surface is composed of several large plates that move and interact with each other, causing phenomena such as earthquakes, volcanoes, and the formation of mountains and ocean basins.

Divergent Plate Boundary: The boundary where two tectonic plates move away from each other, allowing magma to rise and new crust to be formed, as seen at mid-ocean ridges.