Which layer of the Earth moves in different  directions due to  convection AND gravity?

The layer of the Earth that moves in different directions due to convection and gravity is the mantle.

Explanation:

1. Convection Currents: The mantle experiences convection currents caused by the heat from the Earth's core. These currents result in the rising of hot, less dense material and the sinking of cooler, more dense material, creating a cycle that drives the movement of tectonic plates.

2. Gravity's Role: Gravity also influences the mantle's movement. It pulls down on denser materials and assists in the process of subduction, where one tectonic plate moves under another and sinks into the mantle.

Both convection and gravity play essential roles in the dynamic movements of the mantle that ultimately affect tectonic plate boundaries, leading to geological events such as earthquakes and volcanic eruptions. This interplay is crucial for understanding plate tectonics and the Earth's geological activity.