3 Chapter 3

Rocks 3.1 The Rock Cycle  Rocks are any solid mass of mineral or mineral-like matter occurring naturally as a part of our planet.  Types of Rocks The 3 kinds of rocks are igneous, sedimentary, and metamorphic

The Rock Cycle - Interactions between Earth’s water, air, land, and living things can cause rocks to change from one type to another

The Rock Cycle

Igneous Rocks formed by the crystallization of molten magma or lava. Magma is molten material deep beneath the Earth’s surface Lava is molten material above the surface Igneous Rocks

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 (above the Earth’s surface).

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 Granite

Fine-Grained Igneous Texture Rhyolite

Classification of Igneous Rocks 3.2 Igneous Rocks 1. Texture (continued) Glassy texture is caused by very rapid cooling. 2. Composition What minerals the rock is made of, based on the proportions of light and dark minerals in the rock.

Obsidian Exhibits a Glassy Texture.

Porphyritic Igneous Texture

Basalt

Classification of Igneous Rocks

Formation of Sedimentary Rocks 3.3 Sedimentary Rocks Erosion involves the weathering and the removal of rock. Deposition occurs when an agent of erosion—water, wind, ice, or gravity—loses energy and drops sediments. Sedimentary Rocks

Sedimentary Rock Formation

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.

3 Types of Sedimentary Rock Clastic – composed of weathered bits of rocks and minerals –Classified by particle size –Ex: Shale, Sandstone, Conglomerate, Grand canyon & the wave in Arizona

Shale with Plant Fossils

Sandstone

Conglomerate

The Wave, Page, AZ

Grand Canyon, Arizona

3 Types of Sedimentary Rock Chemical – When minerals dissolve out of water –Ex: limestone (caves), coal, rock salt

Fossiliferous Limestone

Carlsbad Caverns, NM Stalactites Stalagmites

3 Types of Sedimentary Rock Organic – Formed by fossils or organic matter within the rock layers

Classification of Sedimentary Rocks

Formation of Metamorphic Rocks 3.4 Metamorphic Rocks  Metamorphism means “to change form.”  Igneous and sedimentary rocks change at elevated temperatures and pressures deep within the Earth or during mountain building Metamorphic Rocks

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 magma Dissolves original minerals and then deposits 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