how dose the sea floor spreading cause tectoni plates to move
http://www.geography4kids.com/files/earth_tectonics.html
http://www.google.com/search?q=sea+floor+spreading+tectonic+plates+for+kids&rlz=1C1AVSX_enUS414US423&espv=210&es_sm=122&tbm=isch&tbo=u&source=univ&sa=X&ei=H_dmUo3RF4nkyAGrh4CAAw&ved=0CCkQsAQ&biw=711&bih=453
Sea floor spreading is a process that occurs at mid-ocean ridges, where new oceanic crust is formed. It plays a key role in the movement of tectonic plates. Here's how it works:
1. Magma Upwelling: At mid-ocean ridges, hot molten rock called magma rises from the Earth's mantle. This occurs because of convection currents within the mantle. As the magma reaches the surface, it cools and solidifies, creating new oceanic crust.
2. Formation of New Oceanic Crust: As the magma cools and solidifies, it forms a new layer of oceanic crust. This process adds material to the edges of the tectonic plates.
3. Plate Divergence: The new oceanic crust formed at the mid-ocean ridges pushes the existing crust aside. This leads to the divergent movement of tectonic plates, where the plates move away from each other.
4. Ridge Push and Slab Pull: Two forces contribute to the movement of tectonic plates. First, the elevated mid-ocean ridges create a gravitational force known as "ridge push." This force pushes the plates apart. Second, the older, denser oceanic crust sinks into the mantle at subduction zones, creating a force called "slab pull." The sinking slab tugs the rest of the plate with it, further facilitating plate movement.
5. Continuous Cycle: As the new oceanic crust is formed and moves away from the mid-ocean ridges, it becomes older and denser. Eventually, it reaches a subduction zone where it is pushed beneath another tectonic plate. This recycling process continues, perpetuating the movement of tectonic plates.
So, sea floor spreading provides the mechanism for the continuous formation of new oceanic crust, leading to the divergent movement of tectonic plates. This movement is driven by forces such as ridge push and slab pull.