Which statement is correct about the movement of plates that sit on top of the mantle?
A. They never move because they are connected to mountains.
B. They never move because they are connected to Earths crust.
C. They regularly move because of convection currents of oceans.
D. They regularly move because of the convection currents of magma.
D. They regularly move because of the convection currents of magma.
D. They regularly move because of the convection currents of magma.
To determine the correct statement about the movement of plates that sit on top of the mantle, we need to understand the process responsible for plate movement. The Earth's surface is divided into several large and small tectonic plates that slowly move relative to each other. This movement is primarily driven by convection currents in the underlying mantle, which is the hot and semi-fluid layer beneath the Earth's crust.
Let's analyze each statement to determine which one is correct:
A. They never move because they are connected to mountains.
This statement is incorrect. Mountains do form at plate boundaries where the collision, separation, or sliding of plates occur. However, this does not mean that the plates themselves do not move. In fact, plate movement is responsible for the creation of mountains.
B. They never move because they are connected to Earth's crust.
This statement is also incorrect. While the tectonic plates are connected to the Earth's crust, they are not stationary. As mentioned earlier, these plates are in constant motion, albeit very slowly.
C. They regularly move because of convection currents of oceans.
This statement is incorrect. While ocean currents do play a role in redistributing the Earth's heat, they are not directly responsible for the movement of tectonic plates. Plate movement is primarily driven by convection currents in the Earth's mantle, not oceans.
D. They regularly move because of the convection currents of magma.
This statement is correct. The movement of tectonic plates is predominantly driven by convection currents in the mantle, specifically the convection of magma. Magma, which is molten rock beneath the Earth's crust, circulates in large-scale convection currents. As the magma rises and cools near the surface, it sinks back down, creating a continuous loop that causes the movement of the tectonic plates resting on top. This process is known as plate tectonics.
Therefore, the correct statement is: D. They regularly move because of the convection currents of magma.