Seafloor Spreading

Definition

Seafloor spreading is the process by which new oceanic crust is created at mid-ocean ridges as tectonic plates pull apart, causing magma to rise from the mantle and solidify. This mechanism plays a critical role in understanding plate tectonics and how continents drift, as it provides evidence for the movement of Earth's lithospheric plates and the formation of ocean basins over geological time.

5 Must Know Facts For Your Next Test

1. Seafloor spreading was first proposed by Harry Hess in the early 1960s, providing a mechanism for continental drift and reshaping our understanding of plate tectonics.
2. Evidence for seafloor spreading includes symmetrical patterns of magnetic striping on either side of mid-ocean ridges, indicating periodic reversals of Earth's magnetic field.
3. As new crust forms at mid-ocean ridges, older crust moves away, leading to the widening of ocean basins over millions of years.
4. Seafloor spreading is crucial in explaining the distribution of earthquakes and volcanic activity along divergent plate boundaries.
5. The process contributes to the rock cycle by creating new basaltic rocks at mid-ocean ridges while recycling older oceanic crust back into the mantle at subduction zones.

Review Questions

• How does seafloor spreading support the theory of plate tectonics and provide evidence for continental drift?
  • Seafloor spreading supports the theory of plate tectonics by demonstrating that tectonic plates are in constant motion. As new oceanic crust forms at mid-ocean ridges and pushes older crust away, it illustrates how continents can drift apart over time. The symmetrical magnetic patterns found on either side of ridges serve as key evidence that supports both the movement of these plates and the historical changes in Earth's magnetic field.
• Discuss the role of mid-ocean ridges in the process of seafloor spreading and their significance in shaping ocean basins.
  • Mid-ocean ridges are essential to seafloor spreading as they are the sites where tectonic plates diverge. As magma rises from the mantle at these ridges, it creates new oceanic crust that gradually expands outward, causing ocean basins to widen. This continuous formation and movement help define the geological features of our oceans and play a significant role in the distribution of marine ecosystems.
• Evaluate the long-term impacts of seafloor spreading on global geological processes and how it affects other aspects like climate change or biodiversity.
  • Seafloor spreading has profound long-term impacts on global geological processes by influencing plate tectonics, leading to earthquakes, volcanic activity, and the formation of mountain ranges. The creation of new oceanic crust also affects ocean circulation patterns, which can have cascading effects on climate systems globally. Additionally, as ocean basins evolve through this process, they create diverse habitats that support various marine life forms, contributing to biodiversity in Earth's oceans.

Related terms

Mid-Ocean Ridge: An underwater mountain range formed by plate tectonics, where seafloor spreading occurs as tectonic plates diverge and magma rises to create new oceanic crust.

Lithosphere: The rigid outer layer of the Earth, composed of the crust and upper mantle, which is broken into tectonic plates that float on the semi-fluid asthenosphere.

Subduction Zone:

A region of the Earth's crust where one tectonic plate moves under another, leading to recycling of oceanic crust and forming deep ocean trenches.