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) Porphyritic (Rhyolite) 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
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 Halite (Rock Salt) Evaporites precipitating from the hyper saline brine water in one of the playa lake, Thar desert Gypsum Rock
Organic Sedimentary Rock Chalk Coal Limestone with Fossils
Clastic Sedimentary Rock Conglomerate (Round) Breccia (Angular) Sandstone (Sand-sized grains) Shale (Clay-sized particles)
Sedimentary Rock Features Cross-beds Stratification in the Grand Canyon Mud Ripples
Formation of Metamorphic Rock Contact Metamorphism
Formation of Metamorphic Rock Regional Metamorphism
Types of Metamorphic Rock FOLIATED ROCK Slate: metamorphic shale Gneiss: metamorphic granite
Types of Metamorphic Rock NONFOLIATED ROCK Quartzite: metamorphic quartz sandstone Marble: metamorphic limestone