Rock types and rock cycle

Types of Rocks… The three main kinds of rock are igneous, sedimentary and metamorphic rock.. – Igneous rock: forms when magma/lava cools and hardens – Sedimentary rock: forms when se

What is a Roc k?

 Naturally-occurring mixtures of

minerals , mineraloids (no crystals), or organic matter.

Types of Rocks…

 The three main kinds of rock are igneous, sedimentary and

metamorphic rock.

– Igneous rock: forms when

magma/lava cools and hardens

– Sedimentary rock: forms when

sediments are buried,

compacted & cemented together

– Metamorphic rock: forms when

existing rock is subjected to

great heat & pressure over a

long period of time

What is the diffe re nc e

be twe e n a roc k and a

mine ral?

 Rocks are made up of ONE or MORE

minerals.

Onc e a roc k is forme d, do e s it

s tay the s ame roc k fore ve r?

 NO !

 Rocks are continually changed by many processes, such as

weathering, erosion, compaction, cementation, melting, and cooling

 Rocks can change to and from the three types

What is the proc e s s through

whic h roc ks c hange ?

 The Rock Cycle—earth materials change back and forth among the different

types of rocks

 No set path a rock takes to become another kind of rock

Weathering, Erosion,

Compaction, Cementation Recrystallization

Solidification

How are roc ks re dis tribute d?

 The core, mantle, & crust are one giant rock recycling machine

 “Ignis” = Latin for “fire”

 Formed from the cooling of either magma or lava

 The most abundant type of rock

 Classified according to their origin and composition

 Igneous Rocks come from magma/lava cooling

down.

ORIGIN — Where rocks are formed

 Below ground = from magma (intrusive igneous rock)

 Usually have LARGE crystal grains (they cooled

slowly) Cooling could have taken hundreds of years.

Some have large & small crystals (called porphyritic)

 Above ground = from lava (extrusive igneous rock)

 Usually have SMALL or NO crystals (they cooled too quickly)

Granite: Intrusive or Extrusive? Why?

Obsidian: Intrusive or

Extrusive? Why?

COMPOSITION — What kind of substances or minerals are rocks made of

Basaltic Igneous Rocks —made from lava/magma that is low in silica , rich

in iron and magnesium Rocks are

dark-colored

Granitic Igneous Rocks —made from magma/lava high in silica and oxygen Rocks are light -

colored.

Andesitic Igneous Rocks — have a composition between basaltic and granitic

Diorite-has course grains

Basalt-no course grains

Granite

 Formed from sediments

(rock fragments, mineral

grains, animal & plant

remains-shells, bones,

leaves, stems) that are

pressed or cemented

together or when sediments

precipitate out of a solution

 These sediments are moved by wind, water, ice

or gravity then deposited into layers

 Sedimentary rocks represent 7% of the

Earth’s crust, but they cover 70% of the

Earth’s surface

 Sedimentary rocks are fossil-carrying rocks

What turns sediments into solid rock?

 Water or wind breaks down and

deposits sediment (erosion & deposition)

 Elements of Erosion are heat, cold, rain, waves, and grinding ice.

 At first sediments fit together loosely, over long periods of time, thick layers build up Because of the heavy layers, the upper layers press down on the

layers below them, causing Compaction.

 Dissolved minerals flow between the particles and cement them together (cementation)

How can sedimentary layers help us

understand the age of fossils?

that the layers on

top (and the fossils

in the top layer) are

fossils in lower

layers

3 Type s of Se dime ntary

Roc ks :

 Clastic (also called Detrial)—made of

broken pieces of other rocks Formed when rock fragments are squeezed

together.

are rounded because

they have been worn

along riverbeds.

 Breccia: Fragments

are jagged with sharp

edges Formed from

various size of rocks

and pebbles.

Organic—remains of plants and animals are deposited in thick layers

were part of living things or were made by living things which contain calcite or

calcium carbonate (Can be tested by

using acid)

3 Type s of Se dime ntary

Roc ks :

by hard shells of once

living things such as

coral, clams, oysters,

and snails When they

die their shells pile up

and are covered by

other sediments

compacting and

cementing them.

 Chemical — minerals dissolved in

lakes, seas, or underground water Can occur when lakes evaporate.

3 Type s of Se dime ntary

Roc ks :

Chemical-Sedimentary Rocks

 Rock Salt: Made of

the mineral halite

 Gypsum: Formed

by evaporation in

dry climates

 Rocks that have changed due to intense

temperature and pressure

 “Meta” means “ change ” and morphosis means “ form ” in Greek

 Igneous, sedimentary and other

metamorphic rocks can change to

become metamorphic rocks

What occurs in the Earth to

change these rocks?

Pressure from overlying rock layers

 High heat, but not enough to melt the rock

 Rocks may be flattened or bent or atoms may

be exchanged to form new minerals.

 *You can think of metamorphic rocks as

a squished peanut butter & jelly

sandwich in your lunch.

Where do me tamorphic roc ks

 Places that are covered miles thick

with other rock causing pressure

 When hot water intrudes rock

 Where a meteorite strikes Earth

(rare)

 Where lightning bolts strike rocks

(rare)

How are me tamo rphic ro cks c las s ified?

Lo o k at Pag es 162-163 in yo ur boo ks

 Foliated —mineral grains are flattened and line up in parallel bands

rearrangement of minerals in granite

into bands

Ho w are me tamorphic roc ks c las s ifie d?

 Non-Foliated — No bands are formed

Rocks Transformed

Rocks Transformed

Say you have an unknown rock

how do you classify it?

 Color: Like with

Say you have an unknown rock

how do you classify it?

useful Look at and feel

the rocks surface

glassy others are rough

and chalky.

or Jagged

Layers, Wavy, banded, or

random.

cool to fast to have grains.

Say you have an unknown rock

how do you classify it?

 You can use acid to

check for carbonates

(Limestone or Chalk)

Say you have an unknown rock

how do you classify it?

 Origin: Where it came

material that come

from rocks or living

things (Smoother)

Rock Cycle Animations

 Rock Cycle Quiz

 Rock Cycle Animation #1

 Weathering and Erosion Quiz

 Rock Cycle Video (Made by a M

iddle School Student)

 Go to the next slide to play

Jeopardy

Jeopardy Game

The Rock Cycle

Question 4

rock can be broken

into fragments that may later form sedimentary rock.

Igneous

Check Answer

Question

12

Sometime temperature and

pressure are great enough to melt rock, forming

magma

Check Answer

Question

13

_ texture – mineral grains flatten and line up in parallel layers or bands.

Foliated texture

Check Answer

Question

15

Sometimes flattens mineral grains in rocks without

melting them.

Pressure

Check Answer

Question

18

Rock fragments, mineral grains,

and bits of plants and animal

remains moved by wind, water, ice

or gravity are called

_.

sediments

Check Answer

Question

20

_ _ rocks are made from the remains of once – living plants or animals.

Organic sedimentary

Check Answer