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Answer:

Sea-floor spreading occurs in the oceanic ridges. In there, volcanic activity, together with the gradual movement of the bottom, form new oceanic crust. This allows a better understanding of the continental drift explained by the theory of plate tectonics.

The greatest evidence for Sea-floor spreading is the oceanic trenches, the oceanic ridges, the magma protruding to the surface and the new seafloor.

In previous theories,  continents were assumed to be transported across the sea. Harry Hess, in the 1960s, proposed the idea that the seabed itself moves  as it expands from a central point. The theory is now accepted, and the phenomenon is thought to be caused by convection currents in the upper layer of the mantle.

Seafloor spreading  

  • Seafloor spreading is a geological process that involves the gradual addition of new oceanic crust in the oceanic floor while moving older rocks away from the mid-oceanic ridge. In other words, it is the process in which the tectonic plates on the oceanic floor move apart from each other.
  • The process occurs when the seafloor spreads apart along divergent boundaries and forms the mid-ocean ridge.
  • Magma is pushed up through cracks in the crust along the mid-ocean ridge. As the magma is thrust up and hardens it forms the new crust and the ocean floor on both sides of the mid-ocean ridge move outward.

Evidence of seafloor spreading  

1. Rocks near mid-ocean ridge were younger than rock near trenches. Rocks away from the mid-oceanic ridges are relatively older than those near it.  

Additionally, the older rocks are denser and thicker compared to thinner and less dense rocks near the mid-oceanic ridge.

2. Matching bands of magnetic rocks were found on either side the mid-ocean ridge; bands like tree rings - record changes in earth's magnetic field over time.

This means sea floor contains different rocks based on ages and are positioned equally in opposite directions. This indicates that there is constant movement and spreading of rocks on the ocean floor.

3. Earthquake data showed oceanic crust is sinking on to the mantle at trenches.  

Keywords: Seafloor spreading, evidence of seafloor spreading  

Learn more about;

  • Seafloor spreading: https://brainly.com/question/7951153
  • Evidence of seafloor spreading: https://brainly.com/question/7951153

Level: High school  

Subject: Geography  

Topic: Geology  

Sub-topic: Seafloor spreading  

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