Formation of Igneous Rocks

Formation of Igneous Rocks Source Molten Rock Composition (3 Components) Liquid Solid Volatiles Creation Juvenile Material Remelting Rock Water/Volatile Addition Roll of Temperature and Pressure Location Beneath Surface (Intrusive) Magma Very-slow cooling Large Crystals At Surface (Extrusive) Lava Slow cooling Small Crystals Above Surface (Extrusive) Pyroclastics Very-fast cooling Exposure to air Exposure to water No Crystals

MAGMA CRYSTALIZATION

Where Igneous Rocks Form

Igneous Rock Formation Magma Molten rock beneath earth’s surface It is less dense than surrounding rock, so it rises (like ice in a Coke®) Lava Molten rock at or near earth’s surface As molten rock cools, it forms IGNEOUS ROCK

Igneous Rock Formation INTRUSIVE igneous rock Forms when magma cools and hardens beneath the earth’s surface. Coarse (large) grained rock, because the crystals (xtls) have more time to grow EX: granite, diorite, gabbro

Igneous Rock Formation EXTRUSIVE igneous rock Forms when lava cools and hardens near the earth’s surface. Fine (small) grained rock, because the crystals (xtls) don’t have time to grow very large EX: rhyolite, andesite, basalt

Igneous Rock Formation PYROCLASTIC Igneous Rock Forms when lava cools instantly as it hits air or water at the surface of the earth No crystals at all May have holes (porous) because gases don’t have time to escape before lava cools. EX: scoria, pumice, obsidian

PYROCLASTIC EXTRUSIVE INTRUSIVE scoria, obsidian, pumice rhyolite andesite basalt INTRUSIVE granite, diorite, gabbro

THE END