Earth Science 2.1 : The Rock Cycle

ROCKS: MINERAL MIXTURES

Earth Science

Chapter 2.1

Objectives:1. Describe two ways rocks have been

used by humans.

2. Describe four processes that shape Earth’s features.

3. Describe how each type of rock changes into another type as it moves through the rock cycle.

4. List two characteristics of rock that are used to help classify it.

The Rock Cycle

Rock naturally occurring solid mixture of one or more

minerals or organic matter New rock forms from old rock material

constantly Rock cycle

The series of processes in which a rock forms, changes from one type to another, is destroyed, and forms again by geological processes

The Value of Rock Important natural resource for as long as

humans have existed Ancient and modern civilizations

used granite, limestone, marble, sandstone, slate and other rocks as construction materials

Important ingredient in concrete and plaster, both of which are commonly used in construction

Pyramids and Sphinx, Giza, Egypt

Capitol Building

Taj Mahal, India

Stonehenge Brooklyn Bridge

Granite Countertops

Processes that Shape the Earth Certain geological processes make

and destroy rock These processes

Shape the features of our planetInfluence the type of rock that is found in

certain areasGrand Canyon, Arizona

Hawaiian Islands

Weathering, Erosion, and Deposition

WeatheringProcess in which water, wind, ice,

and heat break down rockImportant because it breaks down

rock into fragments of which sedimentary rock is made

ErosionProcess by which wind, water, ice, or

gravity transports soil and sediment from one location to another

Wind

Water

Ice

DepositionProcess in which sediment moved by erosion is dropped and comes to rest

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

How the Cycle ContinuesBuried rock is exposed at the Earth’s surface by a

combination of uplift and erosionUplift

○ 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

Rock Cycle illustratedand erosion

Rock Classification Three main classes

1. Igneous rock

2. Sedimentary rock

3. Metamorphic rock

Each class of rock can be divided further, based on differences in the ways rocks form

obsidian granite

shalesandstone

slatemarble

Igneous rock can be divided againbased on whether the magma from which it

forms cools on the Earth’s surface or below ground

Sedimentary and metamorphic rocks are also divided into smaller groups

Scientists study rocks in detail using two important criteria:1. Composition

2. Texture

CompositionChemical makeup of a rockCan describe either the minerals or other

materials in the rock

Texture Quality of a rock that is based on the sizes,

shapes, and positions of the rock’s grains

limestone

aragonite

calcitePercent

5%

95%

Fine-grained

siltstone

medium-grained

sandstone Conglomerate

Coarse-grained