EARTH SCIENCE Prentice Hall EARTH SCIENCE Tarbuck Lutgens 

What is the rock cycle? 3.1 The Rock Cycle  The rock cycle shows the interrelationships and the processes that create and destroy the three rock types.

What are rocks? 3.1 The Rock Cycle  Rocks are any solid mass of mineral or mineral-like matter occurring naturally as part of our planet.  What types of rocks exist on Earth? 1. Igneous rock is formed by the crystallization of molten magma.

3.1 The Rock Cycle 2. Sedimentary rock is formed from the weathered products of preexisting rocks that have been transported, deposited, compacted, and cemented. 3. Metamorphic rock is formed by the alteration of pre-existing rock deep within Earth (but still in the solid state) by heat, pressure, and/or chemically active fluids.

The Rock Cycle 3.1 The Rock Cycle  Processes within the rock cycle:  Compaction and Cementation- “gluing” together of sediments  Cooling and crystallization of magma and lava  Melting from high pressures and temperatures  Weathering-process in which rocks are broken down by water, air, and living things  Erosion-transporting of sediments (bits of rock and minerals) by wind, water, ice, or gravity.

What energy powers the rock cycle? 3.1 The Rock Cycle  Processes driven by heat from the Earth’s interior are responsible for forming both igneous rock and metamorphic rock.  Weathering and the movement of weathered materials (erosion) are external processes powered by energy from the sun.

The Rock Cycle

Describe the formation of igneous rocks? 3.2 Igneous Rocks 1. Intrusive igneous rocks are formed when magma hardens beneath Earth’s surface. 2. Extrusive igneous rocks are formed when lava hardens.

How are igneous rocks classified? 3.2 Igneous Rocks 1. Texture (4 types)  Igneous rocks can be classified based on their texture and composition. Coarse-grained texture is caused by slow cooling resulting in larger crystals. Fine-grained texture is caused by rapid cooling resulting in smaller, interconnected mineral grains. Glassy texture is caused by very rapid cooling. Porphyritic texture is caused by different rates of cooling resulting in varied sized minerals.

Course-Grained Igneous Texture

Fine-Grained Igneous Texture

3.2 Igneous Rocks How is composition used to classify igneous rocks? Granitic composition rocks are made mostly of light-colored minerals like quartz and feldspar. 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 composition dark-colored minerals. Ultramafic composition rocks are made mostly from iron and magnesium-rich minerals.

Obsidian Exhibits a Glassy Texture.

Porphyritic Igneous Texture

Basalt

Classification of Igneous Rocks

What processes create sedimentary rocks? 3.3 Sedimentary Rocks  Weathering, Erosion,Deposition, compaction, and cementation are processes involved in the formation of sedimentary rock. Compaction is a process that squeezes, or compacts, sediments. Cementation takes place when dissolved minerals are deposited in the tiny spaces among the sediments. What is the difference between weathering and erosion?

How are sedimentary rocks classified? 3.3 Sedimentary Rocks 1. Clastic sedimentary rocks are composed of weathered bits of rocks and minerals. Classified by particle size  Two Main Groups - Shale (most abundant) Common rocks include - Conglomerate - Sandstone

Shale with Plant Fossils

Conglomerate

3.3 Sedimentary Rocks 2. Chemical sedimentary rocks form when dissolved substances precipitate, or separate, from water. Common rocks include - l imestone — most abundant chemical rock - microcrystalline quartz known as chert, flint, jasper, or agate - evaporites such as rock salt or gypsum - coal

Fossiliferous Limestone

Classification of Sedimentary Rocks

Features of Some Sedimentary Rocks 3.3 Sedimentary Rocks  Features of sedimentary rocks are clues to how and where the rocks are formed

Where are metamorphic rocks formed? 3.4 Metamorphic Rocks  Metamorphism means “to change form.”  Conditions for formation are found a few kilometers below the Earth’s surface and extend into the upper mantle.  Most metamorphic changes occur at elevated temperatures and pressures.

How can rocks change form? 3.4 Metamorphic Rocks  Rocks can change form 2 ways: 1).Contact metamorphism which occurs when magma moves into rock. 2).Regional metamorphism results in large-scale deformation and high-grade metamorphism during mountain building processes. This produces the greatest volume of metamorphic rock.

What are the processes that create metamorphism in rocks? 3.4 Metamorphic Rocks 1. Heat 2. Pressure 3. Hydrothermal Solutions

Origin of Pressure in Metamorphism

Agents of Metamorphism 3.4 Metamorphic Rocks Hot water-based solutions escaping from the mass of magma Promote recrystallization by dissolving original minerals and then depositing new ones  Hydrothermal Solutions

How are metamorphic rocks classified? 3.4 Metamorphic Rocks 1. Foliated Metamorphic Rock 2. Nonfoliated Metamorphic Rock  Two main categories Has a banded or layered appearance Does not have a banded texture

Classification of Metamorphic Rocks

Gneiss Typically Displays a Banded Appearance

Marble — A Nonfoliated Metamorphic Rock