Convection currents in the mantle are the primary cause of tectonic plate movements on the Earth's surface. These convection currents occur due to the transfer of heat from the core to the mantle, creating a cycle of rising and sinking material within the mantle.

- **What are convection currents?**
Convection currents are the circular motion of fluids (in this case, the semi-solid mantle) caused by density differences due to temperature variations. When a fluid is heated, it becomes less dense and rises, while cooler, denser fluid sinks.

- **The role of convection currents in tectonic plate movements**
1. **Heat transfer from the core**: The Earth's core is extremely hot, and this heat is transferred to the mantle above it. The heat causes the mantle material to expand and become less dense, leading to the formation of convection currents.
2. **Rising and sinking of mantle material**: As the mantle material near the core heats up, it becomes less dense and rises towards the Earth's surface. This rising material carries the tectonic plates above it.
3. **Plate movement**: As the hot mantle material reaches the surface, it spreads out, causing the tectonic plates to move laterally. This is known as divergent plate boundaries. At other locations, the cooler, denser mantle material sinks back into the mantle, creating a downward force on the tectonic plates. This is known as convergent plate boundaries.
4. **Creation of subduction zones**: When two tectonic plates collide, one plate may override the other and sink beneath it. This process is called subduction and occurs at convergent plate boundaries. It is facilitated by the downward force created by the sinking of cooler mantle material.

- **Other factors and their roles**
While convection currents are the primary cause of plate movements, other factors can also influence them to some extent. These include:
- **Earth's rotation**: The rotation of the Earth can affect the direction and speed of plate movements but is not the primary cause.
- **Gravitational forces from the Moon**: The gravitational pull of the Moon causes tides on Earth, but its effect on tectonic plate movements is relatively small compared to convection currents.
- **Solar radiation**: Solar radiation primarily affects climate and weather patterns on Earth but does not directly cause tectonic plate movements.

In conclusion, convection currents in the mantle are the main driving force behind tectonic plate movements on the Earth's surface. These currents are caused by the transfer of heat from the core to the mantle, creating a cycle of rising and sinking material that leads to the lateral movement and collisions of tectonic plates.