But unlike an egg’s cracked shell, tectonic plates travel. Think of the mantle as the thick white part of a hard-boiled egg.Earth’s hot, liquid innards also are always in motion.After millions of years, the oldest, coolest parts of the plate sink back into the mantle, where they remelt again.“It’s like a giant conveyor belt,” explains geophysicist Kerry Key at the Scripps Institution of Oceanography. That conveyer belt drives the movement of the plates.
But unlike an egg’s cracked shell, tectonic plates travel. Think of the mantle as the thick white part of a hard-boiled egg.Earth’s hot, liquid innards also are always in motion.
As Earth’s plates kept moving, those landmasses each broke apart more.
As they spread and traveled, they evolved into our modern continents.
Over millions of years, though, those centimeters add up. For instance, roughly 250 million years ago, Earth had one giant landmass: Pangaea.
Plate movement split Pangaea into two huge continents, called Laurasia and Gondwanaland.
That’s because warmer materials are generally less dense than cooler ones, notes geologist Mark Behn.
He's at the Woods Hole Oceanographic Institution in Massachusetts.Some span thousands of kilometers (miles) on a side.In all, a dozen major plates cover Earth’s surface.She’s a geologist at Central Washington University in Ellensburg. If scientists could warn people when these events were coming, they also might help limit damage.continent (in geology) The huge land masses that sit upon tectonic plates.In modern times, there are six geologic continents: North America, South America, Eurasia, Africa, Australia and Antarctic.earthquake A sudden and sometimes violent shaking of the ground, sometimes causing great destruction, as a result of movements within Earth’s crust or of volcanic action.fault In geology, a fracture along which there is movement of part of Earth’s rocky, outermost shell, or lithosphere.Planetary geology is the science of studying the same things about other planets.geophysics The study of matter and energy on Earth and how they interact.Pangaea The supercontinent that existed from about 300 to 200 million years ago and was composed of all of the major continents seen today, squished together.plate tectonics The study of massive moving pieces that make up Earth’s outer layer, which is called the lithosphere, and the processes that cause those rock masses to rise from inside Earth, travel along its surface, and sink back down.subduct or subduction The process by which tectonic plates sink or slide back from Earth’s outer layer into its middle layer, called the mantle.subduction zone A large fault where one tectonic plate sinks beneath another as they collide.So, hot stuff in Earth’s middle “rises up — kind of like a lava lamp,” he explains.“Once it gets back to the surface and cools off again, then it will sink back down.”The rising of hot rock from the mantle to Earth’s surface is called upwelling. Over time, the cooling outer crust becomes thicker and heavier.geology The study of Earth’s physical structure and substance, its history and the processes that act on it.People who work in this field are known as geologists.