Convection currents occur in the MANTLE. The mantle is the second layer of the earth after the crust. The mantle is approximately 2900 km thick. Convection currents are triggered or fueled by the heat from the Earth's core.
The part of the mantle closest to the core gets heated. It then becomes less dense than the layers above so it rises. When this rising plume interacts with the crust it cools and becomes more dense than the layers below and so it sinks and this circular motion continues to form convection currents.
The focus of an earthquake is the point underground where rocks first begin to move. Seismic waves travel outward from the earthquake's focus.
<span>Question#1
According to the scientific community of Alfred Wegener's day, The flaw in his theory of continental drift was he</span> couldn't explain the force that could move Earth's plates.
<span>Question#2</span>
Gravity is the best explanation for the driving force of plate tectonics.
The Milky Way is a spiral galaxy.
Hope this helps!~
