Your Name Earth Science P.# Date Notes: Igneous Rocks Hot molten rock – inside the Earth = magma - outside the Earth = lava Igneous Rx (rocks) are formed by the cooling of magma or lava

*Intrusive  coarse-grained  large crystals  cools slowly Granite is most common -The Idaho Batholith is made of Granite Gabbro

*Extrusive  fine-grained  small crystals  cools quickly Basalt is most common - Snake River Plain is made of basalt (picture near Twin Falls) Rhyolite

Silica makes thicker (viscous) magma that usually cools below surface. Silica rich magma that does make it to the surface is very explosive.

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