Standard S6E5.c

Classify rocks by their process of formation.

What three characteristics do scientists use to identify rocks?

What are the three groups into which geologists classify rocks?

What is a rock’s texture?

What do the three major groups of rock have in common? How are they different?

Rocks are made of minerals and a mixture of other materials

Some rocks are made of a single mineral

When studying a rock sample, geologists observe the rock’s texture, origin and mineral composition

A rock’s texture is the size, shape, and pattern of the rock’s grains

Grain Size a. fine-grained (small-basalt)b. coarse-grained (large-granite)

Grain Shapea. smooth and rounded (conglomerate)b. jagged (breccia)

Grain Patterna. foliated (gneiss)

-mineral grains appear in parallel lines . b. nonfoliated (marble)

- minerals appear randomNo Visible Grain

a. have no apparent grains (obsidian)

Origin how and where the rock was formed

1. igneous rock = forms from the melting, cooling and hardening of molten rock

a. extrusive= formed above the surface (lava)b. intrusive = formed below the surface (magma)

2. sedimentary rock = forms in layers from other rocks, plants, and animals through a process of weathering, erosion, deposition, compaction and cementation

a. clastic rock= formed from other rocksb. organic rock= formed from things once alivec. chemical rock= formed from saltwater solutions

3. metamorphic rock = formed when existing rock is changed by heat, pressure, or chemical reactions

a. foliated rock= minerals arranged in bandsb. nonfoliated rock= grains arranged randomly

By looking at a small sliver of a rock under a microscope, geologists can observe the size and shape of the crystals and identify the minerals the rock contains

Also, geologists can do tests to identify the physical properties of the minerals inside the rock.

Amount of Silicon in the Rock (mineral composition)

1. mafic= dark-colored rocks (poor in silica) (basalt)2. felsic = ligt-colored rocks (rich in silica) (granite)

Compare – Rocks in each group make up the Earth’s crust and are composed of minerals and other materials

Contrast – Rocks are different in the way they are formed

What terms describe a rock’s texture?

A. igneous rock, sedimentary rock, metamorphic rock

B. grain size, grain shape, grain pattern

C. mantle, crust, core

D. clastic, organic, chemical

What three characteristics do scientists use to identify a rock sample?

A. igneous, sedimentary, metamorphic

B. color, luster, hardness

C. inorganic, solid, crystalline struce

D. rock origin, texture, mineral composition

What are the three groups into which geologists classify rocks?

A. grain size, grain shape, grain pattern

B. rock origin, mineral composition, texture

C. igneous, sedimentary, metamorphic

D. luster, color, hardness

Contrast: How are the three groups of rocks different?

Compare: What do the three major groups of rock have in common?

What characteristics are used to classify igneous rocks?

What are the three (3) ways that magma can form?

What is the difference between extrusive and intrusive rocks? Give an example of each.

Why are some igneous rocks dark and others light?

Igneous rock forms when molten rock cools and hardens.

Molten rock = liquid rock

Igneous Rock forms by:

1. melting

2. cooling

3. hardening (solidifying)

Igneous rocks are classified by their origin.

Igneous rocks are classified by the texture of the grains

Igneous rocks are classified by the mineral composition of the rock

Three ways magma can form:

heat/rise in temperature

pressure released

rock changes composition

Three Ways Igneous Rocks Differ1. Igneous rocks differ in origin:

- form either from lava, above the earth’s surface - or from magma, below the earth’s surface.

2. They also differ in texture according to the size and shape of their mineral grains. (course-grained or fine-grained)

3. Igneous rocks differ in mineral composition depending on how much silica and other minerals are present. (felsic or mafic)

1. Origin – form above or below Earth’s surface

2. Texture – how fast they cool off (fine-grained or coarse-grained

3. Mineral Composition - what the rocks are made of

Igneous rock form below and above Earth’s surface.

Intrusive igneous rock – Intrusive rock forms when magmahardens (below) Earth’s surface.

– coarse-grained (large grains)

– below Earth’s surface (from magma)

– ex. granite (light colored rock = felsic)

Extrusive igneous rock – Extrusive rock forms from lava that has erupted (above) Earth’s surface.

– fine-grained (small grains)

– on the Earth's surface (from lava)

– ex. basalt (dark colored rock = mafic)

Intrusive igneous rock –Intrusive rock forms when magma hardens (below) Earth’s surface.

coarse-grained (large grains)

below Earth’s surface (from magma)

ex. granite (light colored rock = felsic)

Extrusive igneous rock –Extrusive rock forms from lavathat has erupted (above) Earth’s surface.

fine-grained (small grains)

on the Earth's surface (from lava)

ex. basalt (dark colored rock = mafic)

Mineral Composition –

Igneous rock rich in silicon/light-colored are felsic rock.

Igneous rock poor in silicon/dark-colored are mafic rock.

Texture – (grain size)

Fine-grained (small) = cools quickly = formed above surface

Coarse-grained (large) = cools slowly = formed below surface

Most igneous rocks are hard, dense, and durable.

Ancient Native Americans used obsidian for making very sharp tools for cutting and scraping.

Granite is used as a building material such as decorative stonework, curbstones, and floors.

Basalt is crushed to make gravel.

The rough surface of pumice makes a good abrasive for cleaning and polishing.

1. Which of the following are ways magma is formed?

a. by compaction and cooling

b. by melting and cooling

c. by changes in composition

d. by weathering and erosion

2. What kind of texture does igneous rock have when magma cools slowly?

a. coarse-grained

b. large-grained

c. fine-grained

d. medium-grained

3. What kind of texture does igneous rock have when magma cools rapidly?

a. coarse-grained

b. medium-grained

c. large-grained

d. fine-grained

4. What kind of rock is formed when magma intrudes into other rock?

a. extrusive igneous rock

b. sedimentary rock

c. intrusive igneous rock

d. organic sedimentary rock

5. What kind of rock is formed from lava that cools on Earth’s surface?

a. organic sedimentary rock

b. sedimentary rock

c. intrusive igneous rock

d. extrusive igneous rock

Stratification

Uh, looks like a

layered cake to me…

Uluru, Australia

White Cliffs of Dover, England

Where does sedimentary rock form?

Describe the formation of sedimentary rock.

Describe the three main categories of sedimentary rock.

Describe four types of sedimentary features or structures.

Sedimentary rocks form from particles deposited by water and wind.

After sediment has been deposited, the processes of compaction and cementation change the sediment into sedimentary rock.

Weathering- the breaking down of rock into sediment by wind and moving water

Erosion – movement of sediment away from its source

Deposition- process of which sediment settles out of the water or wind carrying It into layers.

Compaction- the process that presses sediment or layers together.

Cementation- the process in which minerals crystallize and glue particles of sediment together.

Geologists classify sedimentary rocks according to the type of sediments that make up the rock.

There are three major groups of sedimentary rocks: clastic rocks, organic rocks, and chemical rocks.

A clastic rock forms when sediments are compacted and cemented together.

(rocks made from other rocks)

Examples of clastic rocks:

Shale

Sandstone

Conglomerate

Breccia

Shale forms from tiny particles of clay.

Shale feels smooth, and splits easily into flat pieces

Sandstone forms from the sand on beaches, on the ocean floor, in riverbeds, and in sand dunes.

Sandstone is formed when small particles of sand are pressed and cemented together.

.

Conglomerate is a rock made up of large particles with rounded edges.

Breccia is a rock made up of large fragments with sharp edges.

Organic rock forms from the remains of plants and animals that once lived in the ocean.

The term “organic” refers to substances that were once part of living things.

Three important organic rocks:

Coal

Limestone

Chalk

Coal forms from the remains of swamp plantsburied in water.

Over millions of years, they slowly change into coal.

The hard shell of living things produces limestone.

Chalk forms from sediments made of skeletons of microscopic living things found in the ocean.

Chemical rock forms from solutions of dissolved minerals and water.

Chemical rocks can also form when mineral deposits are left from evaporating seas or lakes.

Examples:

rock salt (halite)

Gypsum

Stalactites – sharp, icicle shapes that grow downward from the ceiling

Stalagmites – cone-shape features that grow from the floor upwards.

Gypsum - found in evaporated sedimentary deposits

Rock Salt (Halite) – forms when large bodies of salt water evaporate

Sedimentary Rock Features:

-Stratification-mud cracks- ripple marks- rain-drop impressions

Grand Canyon, Arizona

The most important feature of sedimentary rock is stratification.

Strata –

- layers of rock

Stratification – the process in which sedimentary rocks are arranged in layers

Location?

Ripple marks are made by the motion of wind and water waves on lakes, oceans, rivers, and sand dunes.

Mud cracks form when fine-grainedsediments at the bottom of a shallow body of water are exposed to air and dry out.

Rain-drop impressions can be preserved in fine-grained sediments, as small pits with raised rims.

Sandstone and limestone are used as building materials.

The White House in Washington, D.C. is built of sandstone.

Limestone is also used to make cement.

Breccia is used as architectural stones for interior building veneers, tiles, window sills and other decorative applications.

Coal is used for electricity, steam, heat and coke production.

Conglomerate has very few commercial uses. Its inability to break cleanly makes and unreliable physical strength a poor candidate for decorative use.

Shale is used for oil and natural gas.

Rock salt is also known as the mineral “halite”. It is often used in the chemical industry or for use as a winter highway treatment. Some halite is processed for use as a seasoning for food.

Gypsum uses include: manufacture of wallboard, cement, plaster of Paris, soil conditioning.

Which process forms sediment?

a. weathering

b. cementation

c. compaction

d. deposition

What are strata?

a. mineral fragments

b. minerals crystallized out of solution

c. layers in sedimentary rock

d. fossils in sedimentary rock

What kind of sedimentary rock is made of fragments of rocks cemented together by a mineral?

a. organicb. stratifiedc. chemicald. clastic

What kind of sedimentary rock is made from solutions of dissolved minerals in water?

a. organicb. chemicalc. stratifiedd. clastic

What kind of sedimentary rock is made from fossils?

a. organic

b. stratified

c. chemical

d. clastic

What is the process called in which sedimentary rocks are arranged in layers?

a. erosion

b. extrusion

c. weathering

d. stratification

How are metamorphic rocks formed?

Describe two ways a rock can undergo metamorphism.

Describe the difference between foliated and nonfoliated metamorphic rock.

What are some examples of metamorphic rock and how are the examples used?

Metamorphic rock is formed when existing rock is changed by heat, pressure, or chemical reactions.

Heat and pressure deep beneath Earth’s surface can change any rock into metamorphic rock.

Metamorphic rocks are classified by the arrangement of their mineral grains.

Metamorphic rocks are rocks in which the structure, texture, or composition has changed.

The two types of metamorphic rocks are called foliated rock and non-foliated rock.

Foliated rock is when the grains are parallel or arranged in planes or bands.

Non-foliated rock refers to where the grains are arranged randomly.

Foliated Rock

Mineral grains are arranged in planes or bands

The effects of metamorphism depend on the heat and pressure applied to the rock.

The picture on the right shows what happens to shale (sedimentary) when it is exposed to more and more heat and pressure

Gneiss

(from granite)

Slate

(from shale)

mineral grains are not arranged in planes or bands

Quartzite

(from quartz)

Marble

(from limestone)

Metamorphism occurs when temperature and pressure in the earth’s crust change.

Minerals present when the rock formed, may not be stable in the new environment

The original minerals will change into minerals that are more stable in the new environment.

Scientists can understand a metamorphic rock’s history by observing the minerals the rock contains.

For example, a metamorphic rock that contains garnet, formed at a greater depth, greater heat and pressure than a rock that contains only chlorite.

The texture or mineral composition of a rock can change if the surroundings change

If the temperature or pressure of the environment is different than the one in which the rock formed, the rock will undergo metamorphism

Meta = change

Morph = shape

Origins of

Metamorphic Rock

This metamorphic rock is an example of how mineral grains were aligned into distinct bands when the rock underwent metamorphism.

Meta = changed

Morph = shape

Contact Metamorphism – happens when rock is heated by nearby magma.

Minerals in surrounding rock changes into other minerals because of increased temperature.

Occurs near igneous intrusions, such as plate movement.

Occurs over small areas

Regional Metamorphism – happens when pressure builds up around rock deep beneath other rock formations or when pieces of the Earth's crust collide with each other

Increased temperature and pressure causing rock to become deformed and chemically changed.

Occurs over large areas, such as mountain ranges.

Contact Metamorphism occurs over small areas, such as next to bodies of magma.Regional Metamorphism occurs over large areas, such as beneath mountain ranges

Metamorphic rock has features that tell you about its history.

In metamorphic rocks, these features are caused by deformation.

Deformation is a change in the shape of a rock caused by a force placed on it.

These forces may cause a rock to be squeezed or stretched.

Folds or bends in metamorphic rock are structures that indicate that a rock has been deformed.

Metamorphic Rock Structures

These large folds occur in metamorphased sedimentary rock along Saglet Fjord in Labrador, Canada

Marble and slate are the two most useful metamorphic rocks and come in a variety of colors.

Marble can be cut into thin slabs and easily polished (Taj Mahal).

Slate , because it is foliated, splits easily into flat pieces and is used for flooring, roofing, outdoor walkways, or chalkboards.

Gneiss is very appealing to the eye. It can be used for buildings, roads and curbs.

Schist is found in preparations for ezcema, and in medicines to cure boils in humans and animals.

There are 3 major rock groups: igneous rocks sedimentary rocks and metamorphic rocks.

Igneous rocks form when molten rock cools and hardens from magma or lava.

Sedimentary rocks form from particles deposited, pressed, and cemented together by water and wind.

Metamorphic rocks form from heat and pressure, or a chemical change.

Forces inside Earth and at the surface produce a rock cycle that builds, destroys, and changes the rocks in the crust.

1. How does metamorphic rock form?

a. by intense heat and pressure

b. erosion, deposition, compaction, cementation

c. melting into lava or magma, then cooling into a new rock

d. by pressing together and then cementation

2. Molten rock beneath Earth’s surface is called

a. lava.

b. magma.

c. sedimentary rock.

d. igneous rock.

3. If you wanted to duplicate conditions in a laboratory that produced metamorphic rock from sedimentary rock, what would you need to do?

a. apply pressure to the rock

b. apply high temperature to the rock

c. apply high pressure and high temperature to the rock

d. let the rock stand under water for a long time

4. Which of the following is a metamorphic rock?

a. granite

b. sandstone

c. limestone

d. marble

5. Metamorphic rocks can be formed from

a. igneous rocks.

b. sedimentary rocks.

c. metamorphic rocks.

d. all rock groups.

6. The rock formed when granite changes to a metamorphic rock is

a. marble.

b. basalt.

c. gneiss.

d. pumice.

7. Metamorphic rocks that have their grains arranged in parallel bands or layered are said to be

a. jagged grained.

b. foliated.

c. nonfoliated.

d. coarse grained.

8. The heat that changes a rock into metamorphic rock comes from

a. friction of plate movement.

b. the sun.

c. the heat of the mantle.

d. chemical rocks in the crust.

9. Which rock’s name comes from the Greek words for “changed” and “shape”?

a. metamorphic

b. sedimentary

c. fossiliferous limestone

d. igneous

10. What are the two ways a rock can undergo metamorphism?

a. weathering and erosion

b. compaction and cementation

c. Contact and Regional

d. cooling and hardening

11. Geologist classify metamorphic rock according to

a. the exterior color of the rock.

b. the overall shape of the rock.

c. the arrangement of the grains that make up the rock.

d. the degree of hardness of the rock.

EQ: What is the rock cycle?

• What materials are rocks made of?

• Describe four processes that change rock from one type to another.

• What are the three main classes of rock?

• Describe two characteristics of rock that are used to help classify it?

What materials

are rocks made

of?

Rock is describe as a naturally occurring solid mixture of one or more minerals and organic matter.

Rocks are made of mixtures of minerals and other materials, although some rocks may contain only a single mineral.

When studying a rock sample, geologists observe the rock’s origin, color and texture and determine its mineral composition.

Texture is described with terms based on grain size, grain shape, and grain pattern.

Most rocks are made up of tiny particles of minerals or other rocks, which are called grains.

A rock’s grains give it its texture.

There are three major groups of rocks: igneous rock, sedimentary rock, and metamorphic rock.

These terms refer to how the rocks in each group were formed (origin).

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

Rocks have been used by humans to make tools and weapons and to construct buildings.

Certain geological processes make and destroy rock.

These processes shape the features of the Earth.

These processes also influence the type of rock that is found in a certain area of Earth’ssurface.

Weathering is the process by which water, wind, ice, and heat break down rock.

Erosion is the process by which sediment is removed from its source.

Deposition is the process by which sediment moved by erosion is laid down.

Uplift is the process by which rock within the Earth moves to Earth’s surface.

Igneous rock is formed when magma or lava is cooled and hardens and solidifies.

Sedimentary rock is formed by the process of weathering, erosion, deposition and compaction and cementation.

Metamorphic rock is formed by heat, pressure or chemical change deep beneath Earth’s surface.

Scientists classify rocks in detail by using two important criteria – composition and texture.

Composition is the chemical makeup of a rock; describes either the minerals or other materials in the rock.

Texture is the quality of a rock based on the sizes, shapes, and positions of the rocks grains.

1. Which of the following rocks is not normally used as a construction material?

a. marble

b. halite

c. limestone

d. granite

2. The process in which wind, water, ice, and heat break down rock is called

a. uplift.

b. intrusion.

c. recystallization.

d. weathering.

3. What forms when rock partially or completely melts?

a. limestone

b. reefs

c. ripple marks

d. magma

4. Scientists classify rocks

a. by composition and texture.

b. by volume.

c. by mass.

d. by color and size.

Solid mixture of one or more minerals and organic matter:

a. composition

b. rock

c. erosion

d. texture

e. rock cycle

f. deposition

Process by which new rock forms from old

rock:

a. composition

b. rock

c. erosion

d. texture

e. rock cycle

f. deposition

Process by which sediment is removed from its source:

a. composition

b. rock

c. erosion

d. texture

e. rock cycle

f. deposition

Process by which sediment is dropped and comes to rest:

a. composition

b. rock

c. erosion

d. texture

e. rock cycle

f. deposition

There are 3 major rock groups: igneous rocks sedimentary rocks and metamorphic rocks.

Igneous rocks form when molten rock cools and hardens from magma or lava.

Sedimentary rocks form from particles deposited, pressed, and cemented together by water and wind.

Metamorphic rocks form from heat and pressure, or a chemical reaction.

Forces inside Earth and at the surface produce a rock cycle that builds, destroys, and changes the rocks in the crust.

Size, shape, and position of grains that make up a rock:

a. composition

b. rock

c. erosion

d. texture

e. rock cycle

f. deposition

10. Which type of rock is MOST LIKELY to form layers?

A. Sedimentary

B. Igneous

C. Metamorphic

D. magma

11. The _________ of a rock is determined by the sizes, shapes, and positions of the minerals the rock contains.

12. ________ metamorphic rock contains minerals that are arranged in plains or bands.

13. The most characteristic property of sedimentary rock is __________.

14. Sedimentary rock is classified into all of the following main categories except _________.

a. clastic sedimentary rock

b. chemical sedimentary rock

c. nonfoliated sedimentary rock

d. organic sedimentary rock

15. An igneous rock that cools very slowly has a __________ texture.

a. foliated

b. fine-grained

c. nonfoliated

d. coarse-grained

The chemical makeup of a rock:

a. composition

b. rock

c. erosion

d. texture

e. rock cycle

f. deposition

16. Igneous rocks form when

a. minerals crystallize from a solution.

b. sand grains are cemented together.

c. magma cools and solidifies.

d. mineral grains in a rock recrystallize.

17. A __________ is a common structure found in metamorphic rock.

a. ripple mark

b. fold

c. sill

d. layer

18. The process in which sediment is removed from its source and transported is called ____________.

a. deposition.

b. erosion.

c. weathering.

d. uplift.

19. Mafic rocks are

a. light-colored rocks rich in calcium, iron, and magnesium.

b. dark-colored rocks rich in aluminum, potassium, silica, and sodium.

c. light-colored rocks rich in aluminum, potassium, silica, and sodium.

d. dark-colored rocks rich in calcium, iron, and magnesium.