106 The History of the Earth: Supplemental Guide 6 | The Three Types of Rocks
Core Vocabulary
artifacts, n. Items made by people from a long time ago
Example: The archaeologists collected artifacts from King Tut’s tomb.
Variation(s): artifact
igneous, adj. A type of rock that forms when molten rock cools, hardens,
and turns solid
Example: Obsidian and granite are two types of igneous rocks.
Variation(s): none
metamorphic, adj. A type of rock that has formed from another rock as a
result of heat and pressure
Example: Marble is a metamorphic rock formed from limestone, a
sedimentary rock.
Variation(s): none
sedimentary, adj. A type of rock that has formed as the result of layers of
sediment pressed together
Example: Coal is a type of sedimentary rock.
Variation(s): none
sediments, n. Tiny pieces of material that sink to the bottom of a liquid
Example: Sediments settled at the bottom of the swimming pool.
Variation(s): sediment