The Earth is in a continuing state of change. Earth’s crust, known as the lithosphere, consists of 15 to twenty transferring tectonic plates. The plates might be considered like items of a cracked shell that relaxation on the new, molten rock of Earth’s mantle and match snugly in opposition to each other. The warmth from radioactive processes throughout the planet’s inside causes the plates to maneuver, generally towards and generally away from one another. This motion is named plate movement, or tectonic shift.

Our planet appears to be like very completely different from the way in which it did 250 million years in the past, when there was just one continent, known as Pangaea, and one ocean, known as Panthalassa. As Earth’s mantle heated and cooled over many millennia, the outer crust broke up and commenced the plate movement that continues right now.

The enormous continent ultimately broke aside, creating new and ever-changing land lots and oceans. Have you ever ever observed how the east coast of South America appears to be like like it will match neatly into the west coast of Africa? That’s as a result of it did, tens of millions of years earlier than tectonic shift separated the 2 nice continents.

Earth’s land lots transfer towards and away from one another at a median price of about 1.5 centimeters (0.6 inches) a yr. That’s in regards to the price that human toenails develop! Some areas, akin to coastal California, transfer fairly quick in geological phrases — nearly 5 centimeters (two inches) a yr — relative to the extra secure inside of the continental United States. On the “seams” the place tectonic plates are available contact, the crustal rocks could grind violently in opposition to one another, inflicting earthquakes and volcano eruptions. The comparatively quick motion of the tectonic plates beneath California explains the frequent earthquakes that happen there.