Mantle convection - is when the plates move around the asthenosphere and the magma moves in circular patterns due to heat.
Movement of tectonic plates is related to convection currents in the earth's mantle. Tremendous heat and pressure within the earth cause the hot magma to flow in convection currents. These currents cause the movement of the tectonic plates that make up the earth's crust.
Answer: Usually on a map, solid lines represent boundaries between nations, or if it is a map of the states, it would represent the borders of the states.
