Tectonic Plates MS-ESS2-3
NGSS

The hypothesis that all the continents are moving very slowly across Earth’s surface
Continental drift
The hypothesis that all the continents are moving very slowly across Earths surface. Continental drift. Continental drift is the idea that Earth's continents are slowly shifting positions over millions of years.

A timeline of Earth's history based on major changes
Geologic time scale
A timeline of Earth's history based on major changes. Geologic time scale. The geologic time scale is a system used by scientists to organize Earth's history into different periods based on significant events and changes like the appearance of new life forms or major extinctions.

A fossil from an organism that existed for a short time, it is used to determine the age of other fossils
Index fossil
A fossil from an organism that existed for a short time, it is used to determine the age of other fossils. Index fossil. An index fossil helps scientists figure out how old other rocks and fossils are because it comes from a species that lived for only a short time and is found in many places.

A long mountain range on the seafloor formed by lava eruptions through Earth’s crust
Mid ocean ridge
A long mountain range on the seafloor formed by lava eruptions through Earths crust. Mid ocean ridge. A mid ocean ridge is an underwater mountain range formed where tectonic plates spread apart and magma rises to create new ocean floor.