Seafloor spreading

Definition

Seafloor spreading is the process by which new oceanic crust is created at mid-ocean ridges, where tectonic plates are moving apart. This phenomenon plays a critical role in plate tectonics, as it contributes to the movement of Earth's lithospheric plates and helps explain the age and distribution of oceanic crust. As magma rises from the mantle and solidifies, it pushes older crust away from the ridge, causing the ocean floor to expand and leading to various geological processes like earthquakes and volcanic activity.

5 Must Know Facts For Your Next Test

1. Seafloor spreading was first proposed by Harry Hess in the early 1960s, providing crucial evidence for the theory of plate tectonics.
2. The age of oceanic crust increases with distance from mid-ocean ridges, meaning that newer crust is found at the ridges while older crust is located further away.
3. Seafloor spreading is responsible for the creation of new ocean basins and can lead to the formation of features like rift valleys and hydrothermal vents.
4. As new crust forms at mid-ocean ridges, it can cause seismic activity along divergent boundaries, contributing to earthquakes.
5. Seafloor spreading also impacts marine ecosystems by creating habitats around hydrothermal vents, which support unique biological communities.

Review Questions

• How does seafloor spreading contribute to the movement of tectonic plates?
  • Seafloor spreading occurs at mid-ocean ridges where tectonic plates are diverging. As magma rises and solidifies at these ridges, it creates new oceanic crust. This process pushes older crust away from the ridge, resulting in the lateral movement of tectonic plates. Essentially, seafloor spreading acts as a mechanism for plate tectonics by continuously renewing and expanding the ocean floor.
• Discuss the relationship between seafloor spreading and geological features such as mid-ocean ridges and rift valleys.
  • Seafloor spreading is directly related to mid-ocean ridges, which are underwater mountain ranges formed by volcanic activity at divergent boundaries. As tectonic plates pull apart at these ridges, new magma fills the gap and solidifies, creating fresh crust. This process can also lead to rift valleys on land where continental plates are separating, further illustrating how seafloor spreading shapes various geological features both underwater and on land.
• Evaluate the significance of seafloor spreading in understanding Earth's geological history and processes.
  • Seafloor spreading is crucial for understanding Earth's geological history because it provides insight into the dynamic nature of our planet's surface. By studying patterns of seafloor age and magnetic reversals recorded in oceanic crust, scientists can reconstruct past plate movements and continental configurations. Additionally, seafloor spreading influences global geology by affecting seismic activity, shaping ocean basins, and influencing biodiversity in marine ecosystems. Thus, it connects various Earth processes that have shaped our planet over millions of years.

Related terms

Mid-ocean ridge: An underwater mountain range formed by plate tectonics, where seafloor spreading occurs.

Subduction zone: A region of the Earth's crust where one tectonic plate moves under another, leading to recycling of oceanic crust.

Plate tectonics: The scientific theory that describes the large-scale movements of Earth's lithosphere and how they shape geological features.