I made play dough to help represent tectonic plates, and how they work. The red play-dough represent the Core and the heat that the Core makes, heat rises, so when the heat rises, it starts to converge or diverge. When the cold air comes in it lowers, and mixes with the heat made by the core, the blue play-dough represents the cold air. When they both mix together they create a circuit. Once the circuit is created the tectonic plates, the green play=dough, might cause the land to diverge making the plates break apart (those are called earthquake). If they converge they make mountains and other land masses. The crust is 4 million years old the sea floor is 200 billion years old. The reason why the sea floor is older than the crus is, because the sea floor was formed first, it is closer to the Core, over time more land is formed over top of crust, that is why their are fossils found deeper an deeper in the ground. So sense the sea floor is 200 million years old, that means that more soil and land was formed over the previous crust over and over again, until we got the crust we have today.