Starter2/22/ Rocks are made of m________ and m__________ are made of compounds which contain 2 or more e_________. 2.Where do the Earth’s rocks come from? 3.What are the 3 layers of the geosphere?

EARTH SCIENCE Prentice Hall EARTH SCIENCE Tarbuck Lutgens 

3 Chapter 3 Rocks 3.1 Define the term rock. 3.2 Identify the three major types of rocks 3.2a Explain how they differ. 3.3 Describe the rock cycle. 3.4 List the forces that power Earth’s rock cycle.

3 Chapter 3 Rocks NC Competency Goals 2.03 Investigate and analyze the processes responsible for the rock cycle: Analyze the origin, texture and mineral composition of rocks. Trace the path of elements through the rock cycle. Relate rock formation to plate tectonics. Identify forms of energy that drive the rock cycle. Analyze the relationship between the rock cycle and processes in the atmosphere and hydrosphere.

Rocks 3.1 The Rock Cycle  Rocks are any solid mass of mineral or mineral-like matter occurring naturally as part of our planet.  There are Three Types of Rocks classified by how they were formed.

 3 Types of Rocks 1.Igneous rock is formed by the crystallization of molten magma (lava). 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  Shows the interrelationships among the three rock types, igneous, sedimentary, and metamorphic.  Remember, the Earth is a closed system. Minerals must cycle to create new rocks.

The Rock Cycle 3.1 The Rock Cycle Vocabulary:  Magma is molten material that forms deep beneath the Earth’s surface.  Lava is magma that reaches the surface.  Weathering is a process in which rocks are broken down by water, air, and living things.  Sediment is weathered pieces of Earth elements. Compact means to put pressure on or squeeze. Cement means to glue together with minerals.

The Rock Cycle

Check you understanding… 1.Which type of rock did not require heat to form? Igneous, Sedimentary, or Metamorphic? 2.The _________ Cycle is a representation of how one type of rock __________ into another. 3.Pieces of rock broken away by weathering are called __________.

Energy That Drives 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.  These external processes produce sedimentary rocks.  Weathering and the movement of weathered materials, (sediment) are external processes powered by energy from the sun.

 3 Types of Rocks 1.Igneous rock is formed by the crystallization of molten magma (lava).

Rocks 3.1 The Rock Cycle  Types of Rocks 2. Sedimentary rock is formed from the weathered products of preexisting rocks that have been transported, deposited, compacted, and cemented..

Rocks 3.1 The Rock Cycle  Types of Rocks 3. Metamorphic rock is formed by the alteration of pre-existing rock deep within the Earth (but still in the solid state) by heat, pressure, and/or chemically active fluids.

Formation of Igneous Rocks 3.2 Igneous Rocks 1. Intrusive igneous rocks are formed when magma hardens beneath Earth’s surface. Larger crystals due to slow cooling

Formation of Igneous Rocks 3.2 Igneous Rocks 2. Extrusive igneous rocks are formed when lava hardens.

Classification of Igneous Rocks 3.2 Igneous Rocks 1. Texture  Igneous rocks can be classified based on their composition and texture. 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.

Course-Grained Igneous Texture Course

Fine-Grained Igneous Texture Fine

Classification of Igneous Rocks 3.2 Igneous Rocks 1. Texture (continued) Glassy texture is caused by very rapid cooling.

Obsidian Exhibits a Glassy Texture.

Classification of Igneous Rocks 3.2 Igneous Rocks 1. Texture Porphyritic texture is caused by different rates of cooling resulting in varied sized minerals.

Classification of Igneous Rocks 3.2 Igneous Rocks 2. Composition Granitic composition rocks are made mostly of light-colored quartz and feldspar.

Classification of Igneous Rocks 3.2 Igneous Rocks 2. Composition (continued) Basaltic composition rocks are made mostly of dark-colored silicate minerals and plagioclase feldspar.

Basalt

Classification of Igneous Rocks 3.2 Igneous Rocks 2. Composition (continued) 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.

Classification of Igneous Rocks

3.3 Sedimentary Rocks  Sedimentary rock is formed from the weathered products of preexisting rocks that have been transported, deposited, compacted, and cemented.

Formation of Sedimentary Rocks 3.3 Sedimentary Rocks Weathering involves rock being broken apart by weather – freezing/thawing, water, or wind. Erosion involves the weathering and the removal of rock.  Preexisting rocks undergo Weathering, Erosion, and Deposition

Formation of Sedimentary Rocks 3.3 Sedimentary Rocks Deposition occurs when an agent of erosion—water, wind, ice, or gravity—loses energy and drops sediments.  Weathering, Erosion, and Deposition

Formation of Sedimentary Rocks 3.3 Sedimentary Rocks Compaction is a process that squeezes, or compacts, sediments. Cementation takes place when dissolved minerals are deposited in the tiny spaces among the sediments.  Compaction and Cementation make the pieces stick together.

Classification of Sedimentary Rocks 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 shale

Conglomerate conglomerate

Classification of Sedimentary Rocks 3.3 Sedimentary Rocks  Two Main Groups 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 LIMESTONE

chert agate

Gypsum

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 Ripple marks indicate a former lake bed

Features of Some Sedimentary Rocks 3.3 Sedimentary Rocks  In undisturbed layers, the oldest layers are at the bottom and the youngest on top.

Features of Some Sedimentary Rocks 3.3 Sedimentary Rocks  Fossils are found in sedimentary rock

Formation of Metamorphic Rocks 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.

Formation of Metamorphic Rocks 3.4 Metamorphic Rocks  Contact metamorphism occurs when magma moves into rock. Changes are driven by a rise in temperature. Occurs near a body of magma

Formation of Metamorphic Rocks 3.4 Metamorphic Rocks  Regional metamorphism results from large-scale deformation (folding) and high-grade metamorphism. Directed pressures and high temperatures occur during mountain building. Produces the greatest volume of metamorphic rock

Agents of Metamorphism 3.4 Metamorphic Rocks  Heat  Pressure Provides the energy needed to drive chemical reactions Causes a more compact rock with greater density

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

Classification of Metamorphic Rocks 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