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15. What happens when plates move apart?

lava surges up to create new crust. usually makes new ocean floor in the open ocean.

Explanation:

as tectonic plates slowly move away from each other, heat from the mantle's convection currents makes the crust more plastic and less dense. This rock (basalt) becomes a new part of Earth's crust. Mid-Ocean Ridges. Seafloor spreading occurs along mid-ocean ridges—large mountain ranges rising from the ocean floor.

Explanation:

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c) troops march forward in close formation against newer, more accurate weapons

it provided for equal trade rights among nations in china.