Rocks and the Rock Cycle Chapter 6

The Rock Cycle What types of rocks were the first type on the Earth?

IGNEOUS

Bowen’s Reaction Series Canadian Geologist, Norman L. Bowen, recognized that certain minerals tend to crystallize first. As they crystallize, they remove specific elements, changing the composition of magma as it cools.

Partial Melting vs. Fractional Crystallization

Classification of Igneous Rocks Intrusive Igneous Rocks Slow cooling below surface Visible crystals Extrusive Igneous Rocks Fast cooling at surface No crystals or very very small crystals

Textures of Igneous Rocks Fine-grained (Rhyolite) Coarse-grained (Granite) Vesicular (pumice) Glassy (obsidian)

Composition of Igneous Rocks FELSIC MAFIC

Types of Lava Mafic Felsic Color Dark Light Composition Magnesium/iron Silica, Aluminum Origin Ocean crust Cont. crust Temp Hot Cool Viscosity Thin Thick Eruption Type Quiet Violent Example Hawaii Mt. St. Helens

Intrusive Igneous Rock Features

Batholith – large mass (100 square km) of igneous rock Stock – smaller version of a batholith Oregon Batholith after surrounding rock has been eroded away

Half Dome, Yosemite National Park

Stone Mountain. GA

Laccolith – magma pushes overlying upward into an arch Bear Butte, Black Hills, South Dakota

Sill – magma flows between layers of rock - horizontal

Dike – igneous formation that cuts across rock layers - vertical A five-mile-long volcanic wall, a dike, radiating from Shiprock in distance

Formation of Sedimentary Rocks Compaction Cementation

Chemical Sedimentary Rocks Form by precipitation of minerals from water when dissolved materials come out of water. Halite (Rock Salt) Halite and Gypsum Evaporites precipitating from the hyper saline brine water in one of the playa lake, Thar desert Gypsum Rock

Gypsum

Gypsum Uses Plaster and Wallboard Other Uses of Gypsum

Halite (Rock Salt)

Organic Sedimentary Rock Formed from the remains of plants or animals Coal Chalk Coquina – limestone with fossil shells Limestone with Fossils

Clastic Sedimentary Rock Conglomerate (Round) Shale (Clay-sized particles) Sandstone (Sand-sized grains) Form when fragments of rocks are compacted and cemented together

Sedimentary Rock Features Cross-beds Stratification in the Grand Canyon Mud Ripples

Metamorphic Rock Contact Metamorphism - Due to contact with an igneous intrusion.

Metamorphic Rock Regional Metamorphism – occurs over a large area like a plate boundary

Types of Metamorphic Rock Foliated = layered or banded Slate: metamorphic shale Gneiss: metamorphic granite Schist – garnet and muscovite

Granite >>>>>Schist

Types of Metamorphic Rock Non-Foliated – No layers Quartzite: metamorphic quartz sandstone Marble: metamorphic limestone