Igneous Rock• Forms when molten rock (magma/lava) cools and

hardens• Cools slowly beneath Earth’s surface = intrusive• Cools rapidly on the surface = extrusive• Intrusive rocks usually have large, visible grains• Extrusive rocks usually have small to no visible grains• Color is based on the amount of silica in the magma

How Igneous Rocks are Formed

Igneous Rocks

Intrusive Igneous Rocks Extrusive Igneous Rocks

Sedimentary Rocks

• Forms from the compaction and cementation of rock pieces, mineral grains, or organic matter called sediments

• Can contain fossils• Sediments are formed through the process of

weathering and erosion of exposed rocks.• Strata are layers of rock, or sometimes soil

3 kinds:–Clastic = made of mineral or rock pieces

(shale; conglomerate; sandstone; Breccia)–Organic = made from plant or animal

remains (coal; coquina; some limestones)–Chemical = made from dissolved minerals in

water (halite; other limestones)

Sedimentary Rocks

Metamorphic Rock

• Forms when rocks are changed into different kinds of rocks by great heat and pressure

• They are heated, squeezed, folded, or changed by contact with hot magma.

• 2 kinds:– foliated = grains are in bands– nonfoliated = no banding

Metamorphic Rocks