Tectonic plates, the massive slabs of Earth’s lithosphere that help define our continents and ocean, are constantly on the move. Plate tectonics is driven by a variety of forces: dynamic movement in the mantle, dense oceanic crust interacting with the ductile asthenosphere, even the rotation of the planet.
 
Geologists studying the Earth use scientific observation and evidence to construct a picture of what the Earth looked like at different periods in the geologic past. Use this map gallery to better understand how plate tectonics created the ocean and continents we are familiar with today.
asthenosphere
Noun

layer in Earth's mantle between the lithosphere (above) and the upper mantle (below).

Noun

one of the seven main land masses on Earth.

dense
Adjective

having parts or molecules that are packed closely together.

ductile
Adjective
capable of withstanding a certain amount of force by changing form before fracturing or breaking.
geologic
Adjective

having to do with the physical formations of the Earth.

geologist
Noun

person who studies the physical formations of the Earth.

Noun

outer, solid portion of the Earth. Also called the geosphere.

Noun

middle layer of the Earth, made of mostly solid rock.

massive
Adjective

very large or heavy.

oceanic crust
Noun

thin layer of the Earth that sits beneath ocean basins.

plate tectonics
Noun

movement and interaction of the Earth's plates.

Noun

object's complete turn around its own axis.

tectonic plate
Noun

massive slab of solid rock made up of Earth's lithosphere (crust and upper mantle). Also called lithospheric plate.