THE ROCK CYCLE & ROCKS

Subtitle

THE ROCK CYCLE

Why do scientists study rocks? • Rocks contain clues about the environment in which they were

formed.

• Volcanic rocks tell a story of volcanic activity

1. A rock is any solid mass of minerals or mineral-like matter that occurs naturally as part of our planet.

2. The three major types of rocks are igneous rocks, sedimentary rocks and metamorphic rocks.

3. Three rocks that do not have minerals or are composed of nonmineral matter.

• Coal

• Pumuce

• Obsidian

THE ROCK CYCLE

1. Interactions among Earth’s (spheres) water, air and land can cause rocks to change from one type to another. The continuous processes that causes rocks to change make up the rock cycle.

THE ROCK CYCLE

2. When magma cools and hardens beneath the surface or as the result of a volcanic eruption, igneous rock forms.

THE ROCK CYCLE

THE ROCK CYCLE

3. Weathering is a process in which rocks are physically and chemically broken down by water, air, and living things to produce sediment.

THE ROCK CYCLE

4. Sediment is made up of weathered pieces of earth materials. Sediment is moved and deposited by water, gravity, glaciers, or wind.

THE ROCK CYCLE

5. Eventually, sediment is compacted and cemented to form sedimentary rock.

THE ROCK CYCLE

6. Under extreme pressure and temperature conditions, sedimentary rock will change into metamorphic rock.

a) If the sedimentary rock melts, it changes to igneous rock

THE ROCK CYCLE

7. Processes driven by heat from Earth’s interior are responsible for forming both igneous and metamorphic rocks.

THE ROCK CYCLE

8. Weathering and the movement of weathered materials are external processes powered by energy from the sun and by gravity.

THE ROCK CYCLE

9. Processes on and near Earth’s surface produces sediementay rocks.

THE ROCK CYCLE

9. Processes on and near Earth’s surface produces sediementay rocks.

IGNEOUS ROCK

HOW ARE INTRUSIVE ROCK AND EXTRUSIVE IGNEOUS ROCKS ALIKE OR DIFFERENT?

1. Different kinds of igneous rocks from when magma and lava cool and harden.

HOW ARE INTRUSIVE ROCK AND EXTRUSIVE IGNEOUS ROCKS ALIKE OR DIFFERENT?

2. Intrusive igneous rock form when magma hardens beneath Earth's surface

a) Silicon, oxygen, plus aluminum, iron, calcium, sodium, potassium, and magnesium and some gases (water vapor)

HOW ARE INTRUSIVE ROCK AND EXTRUSIVE IGNEOUS ROCKS ALIKE OR DIFFERENT?

b) Magma is less dense, it slowly works it way up toward the surface

i. As it rises, it cools-allowing elements to cool and combine to form minerals

ii. Minerals growing size, forming a solid mass of interlocking crystals

iii. granite

HOW ARE INTRUSIVE ROCK AND EXTRUSIVE IGNEOUS ROCKS ALIKE OR DIFFERENT?

3. Extrusive Igneous rock forms when lava hardens. a) Gases have escaped

b) Rhyolite

HOW DOES THE RATE OF COOLING AFFECT AN IGNEOUS ROCK’S TEXTURE

1. Texture and composition are two characteristics used to classify igneous rocks.

a) Texture describes the appearance based on size, shape and arrangement of its interlocking crystals.

b) Composition is based on the proportions of light and dark minerals in the rock.

HOW DOES THE RATE OF COOLING AFFECT AN IGNEOUS ROCK’S TEXTURE?

2. Coarse-grained texture a) Slow cooling of magma or lave results in the formation of large

crystals

HOW DOES THE RATE OF COOLING AFFECT AN IGNEOUS ROCK’S TEXTURE?

3. Fine-grained texture a) Rapid cooling of magma or lava results in rocks with small,

interconnected mineral grains

HOW DOES THE RATE OF COOLING AFFECT AN IGNEOUS ROCK’S TEXTURE?

4. Granitic compositions a) Silicate minerals, Quartz and feldspar plus 10% dark silicate

minerals (biotite mica & amphibole)

b) 70% silica

c) Rhyolite, extrusive granitic rock

d) Intrusive granitic rock make up most of the continental crust.

HOW DOES THE RATE OF COOLING AFFECT AN IGNEOUS ROCK’S TEXTURE?

5. Basaltic compositions a) Dark silicate minerals and plagioclase feldspar

b) Rich in magnesium and iron

c) Typically darker an denser than granitic rocks

d) Basalt

e) Gabbro is an intrusive igneous rock with basaltic composition

f) Makes up ocean floor

SEDIMENTARY ROCKS

DESCRIBE THE MAJOR PROCESSES INVOLVED IN THE FORMATION OF SEDIMENTARY ROCKS.

1. Several major processes contribute to the formation of sedimentary rocks.

2. Weathering, erosion and deposition a) Weathering, any process that breaks rocks into

sediments (rain, water freeing, growing plants etc…)

b)Erosion involves weathering and the removal of rock. When an agent of erosion-water, wind, ice or gravity—loses energy, it drops the sediments in the process called deposition.

DESCRIBE THE MAJOR PROCESSES INVOLVED IN THE FORMATION OF SEDIMENTARY ROCKS.

3. Compaction and cementation a) Change sediments into sedimentary rock

b) Compaction is the process that squeezes, or compacts, sediments. i. Compaction is caused by the weight of sediments.

ii. Water in the sediments is squeezed out

c) Cementation takes place when dissolved minerals are deposited in the tiny spaces among the sediments

WHAT ARE CLASTIC SEDIMENTARY ROCKS?

WHAT ARE CLASTIC SEDIMENTARY ROCKS?

1. Sedimentary rocks can be classified into two main groups according to the way they form.

2. Clastic sedimentary rocks a) Many different minerals

b) Most common are clay and quatz

c) Can be grouped according to the size of the sediments in the rocks

d) Rounded, Large particles, are called conglomerate

e) Angular particles are called breccia

f) Sand- size grains are called sandstone

WHAT ARE CHEMICAL SEDIMENTARY ROCKS?

3. Chemical sedimentary rocks form when dissolved substances precipitate or separate from water solution

a) Water evaporates or boils off leaving a solid product

b) Limestone, rock salt, chert, flint, and rock gypsum

WHAT FEATURES ARE UNIQUE TO SOME SEDIMENTARY ROCKS?

1. The many unique features of sedimentary rocks are clues to how, when and where the rocks formed.

a) Each layer, is a record of time (history) b) Fossils are found in sedimentary rocks c) Can answer questions like:

i. What kind of climate? Hot or cold ii. Did it form in an ocean or on land? iii. When did the rock form? Hundreds, thousands, millions or

billions of years ago?

METAMORPHIC ROCK

GEOSPHERE

1. The geosphere is not uniform, it is divided into three main parts based on differences in composition– the core, the mantle, and the crust.

WHERE DOES MOST METAMORPHISM TAKE PLACE?

1. Most metamorphic changes occur at elevated temperatures and pressures. These conditions are found a few kilometers below Earth’s surface and extend into the upper mantle.

HOW IS CONTACT METAMORPHISM DIFFERENT FROM REGIONAL METAMORPHISM?

1. Contact metamorphism a) During contact

metamorphism, hot-magma moves (forces) into rock

b) Produces low-grade metamorphism

c) Minor changes to the rock

d) Marble forms when magma intrudes a limestone rock

HOW IS CONTACT METAMORPHISM DIFFERENT FROM REGIONAL METAMORPHISM?

2. Regional metamorphism

a) Mountain building

b) Extreme heat and pressure

c) Regional metamorphism result in large-scale deformation and high-grade metamorphism

WHAT ARE THREE AGENTS OF METAMORPHISM, AND WHAT KINDS OF CHANGES DOES EACH CAUSE?

1. The agents of metamorphism are heat, pressure and hydrothermal solutions.

a) Heat, from magma and the change in temperature depth

• provides energy needed to drive chemical reactions

• Recrystallization

• Cause new minerals to form

WHAT ARE THREE AGENTS OF METAMORPHISM, AND WHAT KINDS OF CHANGES DOES EACH CAUSE?

b) Pressure (Stress),

• Increases with depth

• Pressure is applied in all directions

• Forms rocks that are more compact with greater density

• May cause recrystallization into new minerals

Increase in both pressure and heat cause rocks to flow rather than fracture; mineral grains tend to flatten and elongate.

WHAT ARE THREE AGENTS OF METAMORPHISM, AND WHAT KINDS OF CHANGES DOES EACH CAUSE?

c) Hydrothermal solutions,

• Hydrothermal solution, hot, water-based solutions escape from a mass of magma

• Solutions surrounding mineral grains help in recrystallization, by making the ions easier to move

• Increase temperature, increases reaction rate

• Promote recrystallization by dissolving original minerals and then depositing new ones

WHAT ARE FOLIATED METAMORPHIC ROCKS AND HOW DO THEY FORM?

1. The texture of metamorphic rocks can be foliated or nonfoliated.

2. Nonfoliated metamorphic rock, does not have a banded texture.

a) Contain only one kind of mineral

3. Foliated metamorphic rock, the alignment of the minerals gives a rock a layered or banded appearance.

a) Rocks undergo contact metamorphism, they become more compact and more dense. Some minerals recrystallize with a preferred direction, for example, right angles to the direction of the force.

HOW ARE METAMORPHIC ROCKS CLASSIFIED?