Silfra is a rift valley that runs along part of the Mid-Atlantic Ridge in Iceland. This picture of Silfra shows an area where large cracks formed as the North American Plate and the Eurasian Plate moved away from each other. In this area, the rift cuts through an underwater spring, causing the cracks to fill with crystal-clear water. Because the water is so clear, it is a popular spot for scuba divers.

Mantle convection is the process that drives plate tectonics. the theory of plate tectonics states that the crust is divided into plates that float on the semi molten mantle below. the circular motion of the magma as it slowly rises and falls or move though convection cells drags the plates along causing them to move. the heat source in the lamp would represent the earth's core. the core is the source of energy that drives convection in the mantle. the lava represents molten magma under the earth's surface. if the lava lamp had floating pieces they would move as the circular motion of the lava in the lamp as it rises and falls would move them along the surface. these floating pieces would represent pieces of the earth's crust. 

Answer collision and mountain formation;

Answer sinking and cooled;

Ascenario that doesnt  include any modern objects like electricity