Sea-floor spreading

Definition

Sea-floor spreading is the process by which new oceanic crust is formed at mid-ocean ridges as tectonic plates pull apart. This mechanism plays a crucial role in the formation and expansion of ocean basins, contributing to geological features like rift valleys and abyssal plains. The continuous cycle of creation and destruction of oceanic crust reshapes the Earth's surface over time, influencing plate tectonics and the overall dynamics of our planet.

5 Must Know Facts For Your Next Test

1. Sea-floor spreading was first proposed by Harry Hess in the early 1960s as a key mechanism for plate tectonics.
2. As new crust forms at mid-ocean ridges, older crust moves away from the ridge, leading to the widening of ocean basins.
3. Magnetic reversals recorded in rocks along mid-ocean ridges provide evidence for sea-floor spreading, showing symmetrical patterns on either side of the ridge.
4. The process of sea-floor spreading contributes to the formation of features such as hydrothermal vents and oceanic trenches.
5. Sea-floor spreading affects global sea levels by changing the volume of ocean basins and can influence climate patterns over geological time scales.

Review Questions

• How does sea-floor spreading contribute to the formation of ocean basins and what geological features are associated with this process?
  • Sea-floor spreading contributes to ocean basin formation by creating new oceanic crust at mid-ocean ridges as tectonic plates diverge. As this new crust forms, it pushes older crust away from the ridge, leading to an increase in the width of ocean basins. This process is also associated with various geological features, such as rift valleys, abyssal plains, and hydrothermal vents that are formed by the activity at these mid-ocean ridges.
• Discuss how evidence from magnetic reversals supports the theory of sea-floor spreading.
  • Evidence from magnetic reversals supports sea-floor spreading through the symmetrical patterns found in the magnetic orientation of rocks on either side of mid-ocean ridges. As new crust forms and cools at these ridges, iron-rich minerals within the rocks align with Earth’s magnetic field, recording its direction at that time. By examining these patterns, scientists can determine the age of the ocean floor and confirm that it spreads outward from the mid-ocean ridge, validating the concept of continuous sea-floor formation.
• Evaluate the long-term implications of sea-floor spreading on Earth's geology and climate over millions of years.
  • The long-term implications of sea-floor spreading on Earth's geology include significant changes in ocean basin size, plate tectonics dynamics, and continental configurations. As oceanic crust is continuously created and destroyed through this process, it affects geological activity such as volcanic eruptions and earthquakes. Additionally, changes in ocean basin volumes influence global sea levels, which can impact climate patterns over millions of years by altering ocean circulation and weather systems, ultimately shaping life on Earth.

Related terms

Mid-ocean Ridge: An underwater mountain range formed by tectonic plates diverging, where sea-floor spreading occurs.

Plate Tectonics: The scientific theory explaining the movement of the Earth's lithosphere, which is divided into tectonic plates.

Subduction Zone: A region where one tectonic plate moves under another, leading to the recycling of oceanic crust back into the mantle.