All of these statements about primary sources are true except: a.
Some examples are letters, diaries, and photos.
b.
They are interpretations of past events, based on evidence and artifacts.
c.
They are created at the time of an event, or very soon after.
d.
They are first hand, or eyewitness accounts of an event.

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. 

Asmall closed hole formed in an outwash plain or moraine. forms when a  glacier retreats then remains stationary. 

Did you know it's illegal to own only one guinea pig in switzerland?   : )