Igneous+Intrusions


 * ** Igneous Intrusions﻿ - An intrusion is liquid rock that forms under the surface of the earth. Magma from under the surface slowly moves its way up from deep within the earth and moves into any cracks or spaces it can find, sometimes pushing existing country rock out of the way.

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**pluton** - igneous rock that hardens underground

**sill** - igneous intrusion the forms between rock layers

**dike** - igneous intrusion that cuts across rock layers

**laccolith** - a mushroom shaped igneous intrusion

**batholith** - largest of all plutons - unknown size - makes up the core of mountains

**stock** - small batholith less than 100 square kilometers

**neck** - the remnants of the hardened lava in the throat of a volcano after erosion

**active** - Currently erupting or showing signs of an eruption

**dormant** - Has erupted in historic times - but shows no sign of erupting

**extinct** - Has not erupted in historic times