Ch. 14: The Rock Cycle • Rocka naturally occurring solid mixture of one or more minerals or organic matter. • Rock Cycle- The Process by which new rock is made by old rock
Section 1 The Rock Cycle The Value of Rock • Ancient and modern civilizations have used rocks as construction materials. • Rock is also an important ingredient in concrete and plaster, used in todays construction
Section 1 The Rock Cycle Processes That Shape the Earth • Weathering- process in which water, wind, ice, and heat break down rock. • Weathering is important because it breaks down rock into fragments of which sedimentary rock is made.
Section 1 The Rock Cycle • The process by which wind, water, ice, or gravity transports soil and sediment from one location to another is called erosion. • The process in which sediment moved by erosion is dropped and comes to rest is called deposition.
Section 1 The Rock Cycle • Heat and PressureSedimentary rock can also form when buried sediment is squeezed by the weight of overlaying layers of sediment. • If the temperature and pressure are high enough, the rock can change into metamorphic rock. • If the rock gets hot enough to melt, this creates the magma that eventually cools to form igneous rock.
Section 1 The Rock Cycle • How the Cycle Continues Buried rock is exposed at the Earth’s surface by a combination of uplift and erosion. • Upliftis the movement within the Earth that causes rocks inside the Earth to be moved to the surface. • When uplifted rock reaches the Earth’s surface, weathering, erosion, and deposition begin.
Section 1 The Rock Cycle • Composition is the chemical makeup of a rock. Composition can describe either the minerals or other materials in the rock. • Textureis the quality of a rock that is based on the sizes, shapes, and positions of the rock’s grains.
Section 1 The Rock Cycle Rock Classification Rock can be three main classes based on how the rock is formed: Igneous rock Metamorphic rock Sedimentary rock
Section 2 Igneous Rock Igneous Rock • Igneous rock forms when hot, liquid rock, or magma, cools and solidifies.
Section 2 Igneous Rock • When magma intrudes, or pushes, into surrounding rock below the Earth’s surface and cools, the rock that forms is called intrusive igneous rock. • Intrusive igneous rock usually has a coarse-grained texture because it is well insulated by surrounding rocks and cools very slowly.
Section 2 Igneous Rock • Igneous rock that forms from magma that erupts, or extrudes, on the Earth’s surface is called extrusive igneous rock. • Extrusive igneous rock, commonly found around volcanoes, cools quickly on the surface and contains very small crystals or no crystals.
Section 3 Sedimentary Rock Sedimentary Rock • Wind, water, ice, sunlight, and gravity all cause rock to physically weather into fragments. • Through erosion, these rock and mineral fragments, called sediment, are moved from one place to another.
Section 3 Sedimentary Rock • The most noticeable feature of sedimentary rock is its layers, or strata. • Stratification is the process in which sedimentary rocks are arranged in layers.
Section 3 Sedimentary Rock Composition of Sedimentary Rock • Clastic sedimentary rockis made of fragments of rocks cemented together by a mineral such as calcite or quartz. • Clasitc sedimentary rocks can have coarse-grained, medium-grained, or fine-grained textures.
Section 3 Sedimentary Rock • Chemical sedimentary rockforms from solutions of dissolved mineral and water. • As rainwater slowly makes its way to the ocean, it dissolves some of the rock material it passes through. • Some of this dissolved material eventually crystallized and forms the mineral that make up chemical sedimentary rock.
Section 3 Sedimentary Rock • Organic sedimentary rockis made up of the skeletons and shells of sea animals. These remains collect on the ocean floor and eventually become cemented together. • Coal is a type of organic sedimentary rock that is formed when decomposed plant material is buried beneath sediment and is changed by increasing heat and pressure.
Section 4 Metamorphic Rock Metamorphic Rock • Metamorphic rocks are rocks in which the structure, texture, or composition of the rock have changed.
Section 4 Metamorphic Rock • Foliated Metamorphic RockThe texture of metamorphic rock in which the mineral grains are arranged in planes or band is called foliated. • Foliated metamorphic rock usually contains aligned grains of flat minerals, such as biotite mica or chlorite.
Section 4 Metamorphic Rock • Nonfoliated Metamorphic RockThe texture of metamorphic rock in which the mineral grains are not arranged in planes or band is called nonfoliated. • Nonfoliated metamorphic rocks are commonly made of one or only a few minerals. • During metamorphism, crystals of these minerals may change in size or the mineral may change in composition in a process called recrystallization.
Section 4 Metamorphic Rock • Metamorphic rock has features that indicates its history. These features are caused by deformation. • Deformationis a change in the shape of a rock caused by a force placed on it. • These forces may cause a rock to be squeezed or stretched. Folds, or bends, in metamorphic rock are structures that indicate a rock has been deformed.