The Rock Cycle Rocks vs Minerals Three Types of Rock Earth’s Layers Rock Formation The Rock Cycle Rock Identification

Diamond, a mineral, embedded in a rock Rocks vs. Minerals Minerals Homogeneous Naturally-occurring Inorganic Defined chemical composition Crystalline structure Single element or compound of elements Rocks Composed of one or more minerals Diamond, a mineral, embedded in a rock

Three Types of Rock

Three Types of Rock Igneous Cooled molten rock Extrusive Intrusive Formed by volcanic processes Cool quickly at or near Earth’s surface Intrusive Cool slowly beneath Earth’s surface

Three Types of Rock Sedimentary Particles of other rock (“clasts”) cemented together Can be made from gravel, sand, silt, mud, or living things

Three Types of Rock Metamorphic Existing rock subjected to intense heat and pressure beneath Earth’s surface

Earth’s Layers

Rock Formation Rocks are recycled in Earth’s layers Molten rock from the mantle cools beneath the surface or rises up onto the crust and cools, forming igneous rock

Rock Formation Intrusion Sill Dike/dyke Formation of intrusive igneous rock within layer of other rock Sill Magma cools between layers, forming sheet of igneous rock; horizontal Dike/dyke Magma intrudes through cracks in rock, approaching surface; vertical or diagonal

Rock Formation

Rock Formation Batholith Wide intrusion

Rock Formation Uplift Rocks of Earth’s crust rise up due to tectonic movement, forming hills and mountains

Rock Formation Erosion Wind and water break off pieces of surface rock and transport it

Rock Formation Clasts: pieces of surface rock Clasts are deposited in an area, then compacted and cemented into sedimentary rocks Lithification: process of compaction and cementation

Lithification Sediments are deposited More sediments are deposited on top Upper layers compact lower layers, squeezing out any water in them Minerals left behind cement clasts together Result is solid sedimentary rock

Rock Formation Rock becomes buried deeper beneath the surface Pressure and heat increase with depth Instead of melting, rocks change, or metamorphose, into another rock Metamorphism Minerals move and align New minerals form Metamorphic rocks also form when existing rocks come into contact with molten rock

Rock Formation Deeper within the Earth, existing rocks melt Melted rock rises to or near the surface and becomes igneous rock

The Rock Cycle

The Rock Cycle Any rock type can become any other type of rock Fill in the label numbers for the image Magma Cooling Igneous rock Erosion Sedimentation Sediments & sedimentary rock Burial and metamorphism Metamorphic rock Melting

Rock Identification Igneous Often contain crystals But, if cooling too fast, crystals don’t form (e.g. obsidian) Some have holes from the formation of air bubbles during cooling Obsidian Granite Pumice

Rock Identification Igneous Extrusive Intrusive Rapid cooling allows formation of small crystals or no crystals Examples: basalt, obsidian, pumice, rhyolite Intrusive Slow cooling allows formation of large crystals Examples: granite, gabbro, peridotite, diorite Basalt Granite

Rock Identification Sedimentary Types Particle type Clastic: form from eroded particles Chemical: form from dissolved minerals that fall out of what they are dissolved in (precipitate) Organic: form from plant or animal debris Particle type Clasts include those from rock and volcanic ash Living organisms form limestone (calcium carbonate), chert (silicon dioxide), and coal (mostly carbon)

Rock Identification Sedimentary: Clast size Silt -> siltstone (very small particles) Mud -> mudstone (very small particles) Sand -> sandstone (intermediate size particles) Gravel: 2 mm to 4 meters Forms conglomerate or breccia Conglomerate: rounded Breccia: sharp and angular Siltstone Sandstone Conglomerate Breccia

Rock Identification Sedimentary Crustal layers predominantly sedimentary rock Sedimentary rocks sometimes have fossils embedded in them

Rock Identification Metamorphic Foliated: layered/banded due to direct pressure Some break into flat pieces Some have a shiny surface Examples: gneiss, schist, slate Non-foliated: not layered or banded Examples: marble, quartzite, hornfels Gneiss Slate Marble