Presentation on theme: "Rocks 3.1 The Rock Cycle Rocks – naturally occurring, solid mass of minerals Types of Rocks 1. Igneous rock - formed by the crystallization of molten."— Presentation transcript:
1 Rocks3.1 The Rock Cycle Rocks – naturally occurring, solid mass of minerals Types of Rocks1. Igneous rock - formed by the crystallization of molten magma/lava.
2 3.1 The Rock Cycle Rocks Types of Rocks 2. Sedimentary rock - formed from weathered products of preexisting rocks that have been transported, deposited, compacted, and cemented.3. Metamorphic rock - formed by the alteration of preexisting rock deep within Earth (still in the solid state) by heat, pressure, and/or chemically active fluids.
3 3.1 The Rock Cycle The Rock Cycle Interrelationships among the three rock types (igneous, sedimentary, and metamorphic) Magma - molten material deep beneath the Earth’s surface. Lava - magma that reaches the surface. Weathering - process in which rocks are broken down by water, air, and living things. Sediment - weathered pieces of Earth elements.
5 3.1 The Rock Cycle Energy That Drives the Rock Cycle Heat from the Earth’s interior forms igneous rock and metamorphic rock. Weathering and erosion are external processes powered by the sun that form sedimentary rocks.
6 3.2 Igneous Rocks Formation of Igneous Rocks 1. Intrusive igneous rocks - formed when magma hardens beneath Earth’s surface.2. Extrusive igneous rocks - formed when lava hardens at Earth’s surface.
7 3.2 Igneous Rocks Classification of Igneous Rocks Igneous rocks are classified by composition and texture.1. Texture• Coarse-grained texture (large crystals) is caused by slow cooling.• Fine-grained texture (small grains) is caused by rapid cooling.
8 3.2 Igneous Rocks Classification of Igneous Rocks 1. Texture (continued)• Glassy texture is caused by very rapid cooling.• Porphyritic texture is caused by different rates of cooling resulting in varied mineral sizes.2. Composition• Granitic composition rocks are made mostly of light-colored quartz and feldspar.
9 3.2 Igneous Rocks Classification of Igneous Rocks 2. Composition (continued)• Basaltic composition rocks are made mostly of dark-colored silicate minerals and plagioclase feldspar.• Andesitic composition rocks are between granitic, light-color minerals and basaltic, dark-colored minerals.• Ultramafic composition rocks are made mostly from iron and magnesium-rich minerals.
11 3.3 Sedimentary Rocks Formation of Sedimentary Rocks • Weathering – breakdown of rockErosion – transport of broken sediments• Deposition - when an agent of erosion—water, wind, ice, or gravity—drops sediments.
12 3.3 Sedimentary Rocks Formation of Sedimentary Rocks • Compaction - process that squeezes/compacts sediments.• Cementation - when dissolved minerals are deposited in the tiny spaces of sediments. Features of sedimentary rocks are clues to how and where the rocks are formed
13 3.3 Sedimentary Rocks Classification of Sedimentary Rocks 1. Clastic sedimentary rocks - composed of weathered bits of rocks and minerals.• Classified by particle size• Common examples:- Shale (most abundant)- Sandstone- Conglomerate
14 3.3 Sedimentary Rocks Classification of Sedimentary Rocks 2. Chemical sedimentary rocks form when dissolved substances precipitate, or separate, from water.Common rocks include- limestone—most abundant chemical rock- microcrystalline quartz known as chert, flint, jasper, or agate- evaporites such as rock salt or gypsum- coal
16 3.4 Metamorphic Rocks Formation of Metamorphic Rocks Metamorphism means “to change form.” Formation occurs at high temperatures and pressures. Conditions are found a few km below the Earth’s surface and extend into the upper mantle.
17 3.4 Metamorphic Rocks Formation of Metamorphic Rocks Contact metamorphism occurs when magma moves into rock.Occurs near a body of magmaChanges are driven by a rise in temperature.
18 3.4 Metamorphic Rocks Formation of Metamorphic Rocks Regional metamorphism results in large-scale deformation and high-grade metamorphism.Directed pressures and high temperatures occur during mountain building.Produces the greatest volume of metamorphic rock
19 3.4 Metamorphic Rocks Agents of Metamorphism Heat Pressure Provides the energy needed to drive chemical reactions PressureCauses a more compact rock with greater density
20 3.4 Metamorphic Rocks Agents of Metamorphism Hydrothermal Solutions Hot water-based solutions escaping from the mass of magmaPromote recrystallization by dissolving original minerals and then depositing new ones
21 3.4 Metamorphic Rocks Classification of Metamorphic Rocks Two main categories1. Foliated Metamorphic RockHas a banded or layered appearance2. Nonfoliated Metamorphic RockDoes not have a banded texture