Transcript Rock Notes
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 MAFIC FELSIC Types of Lava Mafic Color Dark Composition Magnesium/ir on Origin Ocean crust Temp Hot Viscosity Thin Eruption Type Quiet Example Hawaii Felsic Light Silica, Aluminum Cont. crust Cool Thick Violent 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 A five-mile-long volcanic wall, a dike, radiating from Shiprock in distance Dike – igneous formation that cuts across rock layers vertical Formation of Sedimentary Rocks Compaction Cementation Chemical Sedimentary Rocks Halite and Gypsum Form by precipitation of Halite (Rock Salt) minerals from water when dissolved materials come out of water. 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 Limestone with Fossils Coquina – limestone with fossil shells Clastic Sedimentary Rock Conglomerate (Round) Sandstone (Sand-sized grains) Shale (Clay-sized particles) 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