Geological EvolutionGeological Evolution

What are Rocks?What are Rocks?

A rock is a naturally occurring A rock is a naturally occurring solid mixture of one or more solid mixture of one or more minerals, or organic matterminerals, or organic matter

Rocks are classified by how they Rocks are classified by how they are formed, their composition, are formed, their composition, and textureand texture

Rocks change over time through Rocks change over time through the rock cyclethe rock cycle

AnimationAnimation

http://www.bbc.co.uk/schools/ks3bitesize/science/environment_earth_universe/rock_cycle/activity.shtml

Types of RocksTypes of Rocks

Sedimentary Rocks

Metamorphic RocksIgneous Rocks

Igneous RocksIgneous Rocks

Igneous rock begins as magma.Igneous rock begins as magma.

Igneous rocks form from the Igneous rocks form from the cooling of magma or lava.cooling of magma or lava.

The name The name igneousigneous comes from the Latin comes from the Latin word word ignisignis, which means “fire”. , which means “fire”.

http://www.fi.edu/fellows/payton/rocks/create/igneous.htm

Sedimentary RocksSedimentary Rocks

http://www.fi.edu/fellows/payton/rocks/create/sediment.htm

Sedimentary rock is formed by erosion

Sediments are moved from one place to another

Sediments are deposited in layers, with the older ones on the bottom

The layers become compacted and cemented together

Sedimentary RockSedimentary Rock

Metamorphic RockMetamorphic Rock

http://www.fi.edu/fellows/payton/rocks/create/metamorph.htm

Meaning to change shape

Changes with temperature and pressure, but remains solid

Usually takes place deep in the Earth

THE ROCK CYCLE

SEDIMENTARY

METAMORPHIC

Heat & Pressure

IGNEOUS

Heat & Pressure

Weathering, Erosion, Deposition, Cementation, Compaction

Weathering, Erosion, Deposition, Cementation, Compaction

Melting & Cooling

Melting & Cooling

Weathering, Erosion, Deposition, Cementation, Compaction

Heat & Pressure Melting & Cooling

Where do IGNEOUS ROCKS form?

Extrusive igneous rocks form on or near the surface.

Intrusive igneous rocks form below the surface.

Where do sedimentary rocks form?

SEDIMENTARY ROCKS form near the surface under water by COMPACTION from a few layers above.

Where do METAMORPHIC ROCKS form?

METAMORPHIC ROCKS form deep underground by Pressure from many layers above.

THE ROCK CYCLE

http://www.bbc.co.uk/schools/ks3bitesize/http://www.bbc.co.uk/schools/ks3bitesize/science/environment_earth_universe/science/environment_earth_universe/rock_cycle/activity.shtml ****rock_cycle/activity.shtml ****

http://www.makemegenius.com/http://www.makemegenius.com/video_play.php?id=108video_play.php?id=108

FossilsFossils Fossils are usually Fossils are usually found in found in sedimentarysedimentary rocks.rocks.

When an organism When an organism dies, its soft parts dies, its soft parts often decay quickly often decay quickly leaving only the hard leaving only the hard parts to fossilize.parts to fossilize.

Ex. Bones, Shells, Ex. Bones, Shells, Teeth, or SeedsTeeth, or Seeds

FossilsFossilsFossilsFossils are are preserved remains or preserved remains or traces of living things.traces of living things.

Most fossils form Most fossils form when living things die when living things die and are buried by and are buried by sediments. sediments.

The sediments slowly The sediments slowly harden into rock and harden into rock and preserve the shape of preserve the shape of the organisms.the organisms.

Scientists who study Scientists who study fossils are fossils are paleontologists.paleontologists.

Types of FossilsTypes of FossilsPetrified FossilsPetrified Fossils: : fossils in which fossils in which minerals replace all or minerals replace all or part of the organism. part of the organism. Ex: petrified woodEx: petrified woodWhen the object is When the object is buried by sediment, buried by sediment, water rich in minerals water rich in minerals seeps into the cells. seeps into the cells. After the water After the water evaporates, hardened evaporates, hardened minerals are left minerals are left behind.behind.

Types of FossilsTypes of Fossils Molds and Molds and CastsCasts

A A moldmold is a is a hollow area in hollow area in sediment in the sediment in the shape of an shape of an organism or part organism or part of an organism.of an organism.

A A castcast is a copy is a copy of the shape of of the shape of an organism.an organism.

Types of FossilsTypes of FossilsTrace FossilsTrace Fossils provide evidence of provide evidence of the activities of the activities of ancient organisms. ancient organisms. Ex: footprints, animal Ex: footprints, animal trails, or animal trails, or animal burrows.burrows.

Types of FossilsTypes of Fossils

Carbon FilmsCarbon Films:: an an extremely thin coating extremely thin coating of carbon on rock that of carbon on rock that forms when materials forms when materials that make up an that make up an organism become organism become gases and escape gases and escape leaving only carbon leaving only carbon behind.behind.

Types of Types of FossilsFossils

Preserved Preserved RemainsRemains are are formed when an formed when an organism is organism is preserved with little preserved with little or no change.or no change.

For example when For example when organisms become organisms become preserved in tar, preserved in tar, amber (tree sap), amber (tree sap), and freezing.and freezing.

Why Study Fossils?Why Study Fossils?Scientists study Scientists study fossils to learn what fossils to learn what past life forms were past life forms were like.like.

Paleontologists Paleontologists classify organisms in classify organisms in the order in which the order in which they lived.they lived.

All the information All the information scientists have scientists have gathered is called the gathered is called the fossil recordfossil record..

Fossil RecordFossil Record The fossil record The fossil record provides evidence provides evidence about the history of about the history of life on Earth.life on Earth.The fossil record The fossil record also shows how also shows how different groups of different groups of organisms have organisms have changed over time.changed over time.It also provides It also provides evidence to support evidence to support the the theory of theory of evolution.evolution.

Remember!Remember!A scientific theory is A scientific theory is a well-tested concept a well-tested concept that explains a wide that explains a wide range of range of observations.observations.

The fossil record The fossil record shows that millions shows that millions of types of of types of organisms have organisms have evolved. evolved.

However, many However, many others became others became extinct.extinct.

Finding the Age of Finding the Age of Rocks Through Rock Rocks Through Rock

DatingDating

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Ages of RocksAges of RocksThe The relative agerelative age of of a rock is its age a rock is its age compared to other compared to other rocks. rocks. Use words like: Use words like: “older or younger”“older or younger”The The absolute ageabsolute age of of a rock is the number a rock is the number of years since the of years since the rock was formed. rock was formed. Ex: 358-360 myaEx: 358-360 mya

Rock Joke!!Rock Joke!!

What does a rock want What does a rock want to be when it grows to be when it grows up?up?

A Rock Star!!A Rock Star!!

The Position of The Position of Rock LayersRock Layers

It can be difficult to It can be difficult to determine a rocks determine a rocks absolute age. So… absolute age. So… scientists use the scientists use the law law of superpositionof superposition..

According to the According to the law law of superpositionof superposition, in , in horizontal horizontal sedimentary rock sedimentary rock layers the oldest layer layers the oldest layer is at the bottom. Each is at the bottom. Each higher layer is higher layer is younger than the younger than the layers below it.layers below it.

Law of SuperpositionLaw of Superposition

The The Law of SuperpositionLaw of Superposition states that states that in in undisturbedundisturbed rock layers the oldest rock layers the oldest layer is on the bottom and the layer is on the bottom and the youngest rock layer is on the top.youngest rock layer is on the top.

The Grand CanyonThe Grand Canyon

Youngest

Oldest

UnconformitiesUnconformities

An An unconformityunconformity is a is a gap in the geologic gap in the geologic record that most record that most commonly occurs when commonly occurs when rock is eroded rock is eroded exposing older rock exposing older rock and then new rock and then new rock forms on the much forms on the much older rock.older rock.The layering of new The layering of new rock on the much older rock on the much older rock leaves a gap in rock leaves a gap in the geologic record.the geologic record.

Other types of UnconformitiesOther types of Unconformities

Faulting- Movement of the Earth’s plates causes rock to crack and shift.

Intrusion- Magma from the Earth’s mantle moves into the rock layers, cools and hardens. (Igneous Rock)

Other types of Unconformites (cont.)Other types of Unconformites (cont.)Folding- Earth’s plates are pressing together. This movement causes them to bend and fold. This process forms mountains.

Erosion- described earlier. Layers of rock are washed away and new rock built on top. Leaves gaps in geologic record.

Examples of when the Law of Examples of when the Law of Superposition may not Superposition may not

apply…apply…FoldingFaulting

Intrusion Erosion

Use the link below to watch Use the link below to watch a simulation of a simulation of unconformities.unconformities.

www.classzone.comwww.classzone.com

Rock Joke!!Rock Joke!!

How do rocks wash How do rocks wash their clothes?their clothes?

The Rock Cycle!!The Rock Cycle!!

Other Clues to Other Clues to Relative AgeRelative Age

Clues From Clues From Igneous RockIgneous Rock

Lava that cools at the Lava that cools at the surface is called an surface is called an extrusion. Rock extrusion. Rock below an extrusion is below an extrusion is always older.always older.

Magma that cools Magma that cools beneath the surface beneath the surface is called an intrusion. is called an intrusion. An intrusion is An intrusion is always younger than always younger than the rock layers the rock layers around an beneath it.around an beneath it.

Other Clues to Relative AgeOther Clues to Relative AgeFaultsFaults (a break in the (a break in the rock) are always rock) are always younger than the younger than the rock it cuts through!rock it cuts through!UnconformitiesUnconformities: An : An unconformity is a unconformity is a gap gap in the geological in the geological recordrecord that can occur that can occur when erosion wears when erosion wears away rock layers and away rock layers and other rock layers other rock layers form on top of the form on top of the eroded surface.eroded surface.

Mechanical WeatheringMechanical Weathering

A type of weathering in which rock is physically A type of weathering in which rock is physically broken into smaller pieces is called broken into smaller pieces is called Mechanical Mechanical WeatheringWeathering..

Types of mechanical weathering include:Types of mechanical weathering include: Freezing and thawingFreezing and thawing Release of pressureRelease of pressure Plant growthPlant growth Actions of animals Actions of animals Abrasion from small particles(sand) and water.Abrasion from small particles(sand) and water.

Chemical WeatheringChemical Weathering

Chemical WeatheringChemical Weathering is the process that is the process that breaks down rock through chemical breaks down rock through chemical changes.changes.Types of chemical weathering include:Types of chemical weathering include: Water dissolving minerals in rocksWater dissolving minerals in rocks Exposure to gases such as oxygen and Exposure to gases such as oxygen and

carbon dioxidecarbon dioxide Acids from living organisms, such as plantsAcids from living organisms, such as plants Acid rainAcid rain

A. Chemical Weathering- Reaction with gases in the air.

B.Mechanical Weathering- pounding of water on rocks

C. Mechanical Weathering- Volcano, pressure

D. Chemical Weathering-

Acid rain

E. Mechanical Weathering-

Plant growth

F. Mechanical Weathering-

Abrasion from sand being picked up by wind and thrown against rock.

Using Fossils to Date Rocks!Using Fossils to Date Rocks!Scientists use index Scientists use index fossils to match rock fossils to match rock layers. layers.

An An index fossilindex fossil must must be widely distributed be widely distributed and represent a type and represent a type of organism that of organism that existed only briefly.existed only briefly.

They are useful They are useful because they tell the because they tell the relative agesrelative ages of the of the rock layers they are rock layers they are found in.found in.

The TrilobiteThe Trilobite

One example of an index One example of an index fossil is a trilobite.fossil is a trilobite.

Trilobites were a group of Trilobites were a group of hard-shelled animals hard-shelled animals whose bodies had three whose bodies had three distinct parts.distinct parts.

They evolved in shallow They evolved in shallow seas more than 500 seas more than 500 million years ago.million years ago.

How might scientist use the age of fossils to date How might scientist use the age of fossils to date rock layers? rock layers? Answer: A fossil found in an older rock layer Answer: A fossil found in an older rock layer would be older than a fossil found in a younger would be older than a fossil found in a younger rock layer.rock layer.

Research the term index fossil. How might an Research the term index fossil. How might an index fossil allow scientists to determine the age index fossil allow scientists to determine the age of rock layers? of rock layers? Answer: Index fossils are organisms that were Answer: Index fossils are organisms that were widespread but only lived for a short period of widespread but only lived for a short period of time, so if a scientist finds a well known index time, so if a scientist finds a well known index fossil (ex. Trilobite) in an unknown rock layer he fossil (ex. Trilobite) in an unknown rock layer he can date the rock layer.can date the rock layer.

Relative Dating of RocksRelative Dating of Rocks

Relative DatingRelative Dating occurs when the age of a rock occurs when the age of a rock is determined by is determined by comparingcomparing it to the age of it to the age of another.another.Scientist use the Law of Superposition as their Scientist use the Law of Superposition as their first step in Relative Dating of rocks, however, first step in Relative Dating of rocks, however, when rock layers are disturbed the Law of when rock layers are disturbed the Law of Superposition may not apply.Superposition may not apply.Index FossilsIndex Fossils are organisms that were are organisms that were widespread but only lived for a short period of widespread but only lived for a short period of time. They are useful because they tell the time. They are useful because they tell the relative ages of the rock layers in which they relative ages of the rock layers in which they occur.occur.

This online, interactive activity will help This online, interactive activity will help with your understanding of Index Fossils with your understanding of Index Fossils and how they help with Relative Datingand how they help with Relative Dating

www.phschool.comwww.phschool.com

Webcode: cfp-2042Webcode: cfp-2042

Absolute Dating of rocksAbsolute Dating of rocks

Absolute Dating/Radioactive DecayAbsolute Dating/Radioactive Decay is when scientists use is when scientists use radioactive radioactive dating dating to determine the absolute ages to determine the absolute ages of rocks. of rocks. –Radioactive decay-over time certain elements break down, or decay, by releasing particles and energy.–Half life- The constant rate of decay of an element. (Carbon 14 has a half-life of 5,730 years)

Half life of Carbon-14Half life of Carbon-14

Will the amount of radioactive substance ever Will the amount of radioactive substance ever be zero? Justify your answer. be zero? Justify your answer. Answer: No, the amount of radioactive Answer: No, the amount of radioactive material will never be zero because as long material will never be zero because as long as you are cutting the material in half-there as you are cutting the material in half-there will always be some left to cut.will always be some left to cut.

How do scientists use the amount of How do scientists use the amount of radioactive elements found in rocks to radioactive elements found in rocks to determine the actual age of the rock? determine the actual age of the rock? Answer: Based on the amount of radioactive Answer: Based on the amount of radioactive material and what type of radioactive material and what type of radioactive material, they can calculate exactly how old material, they can calculate exactly how old the rock is.the rock is.

Is the process of absolute dating using Is the process of absolute dating using radioactive elements error proof? Justify your radioactive elements error proof? Justify your answer. answer. Answer: Yes, radioactive material decays at a Answer: Yes, radioactive material decays at a constant rate always, therefore, the precise date constant rate always, therefore, the precise date will be reliable.will be reliable.

How has the evolution of technology aided How has the evolution of technology aided scientists in their ability to date rock layers? scientists in their ability to date rock layers? Answer: This process would be impossible to Answer: This process would be impossible to calculate without computers and necessary calculate without computers and necessary technology to detect the amount of radioactive technology to detect the amount of radioactive material present.material present.

Remember the difference!Remember the difference!

The The relative agerelative age of a rock is its age of a rock is its age compared to other rocks. compared to other rocks. Use words like: “older or younger”Use words like: “older or younger”

The The absolute ageabsolute age of a rock is the number of a rock is the number of years since the rock was formed. of years since the rock was formed. Ex: 358-360 myaEx: 358-360 mya

Ice CoresIce Cores

Scientists study ice cores to understand Scientists study ice cores to understand how the climate has changed.how the climate has changed.

Lower layers are older than higher layers Lower layers are older than higher layers (Law of Superposition)(Law of Superposition)

Layers record concentrations of gases like Layers record concentrations of gases like COCO2 2 and deuterium (a heavy form of and deuterium (a heavy form of hydrogen.hydrogen.

Where do scientists obtain ice cores from? Where do scientists obtain ice cores from? Answer: Scientists drive a hollow tube deep into Answer: Scientists drive a hollow tube deep into

miles thick ice sheets in Antarctica and miles thick ice sheets in Antarctica and Greenland or any glacier.Greenland or any glacier.

Does global climate shift gradually or can it shift Does global climate shift gradually or can it shift rapidly?rapidly?

Justify your answer by giving an example from the Justify your answer by giving an example from the link. link.

Answer: Global climate can shift gradually, Answer: Global climate can shift gradually, sometimes in a matter of years. For example, sometimes in a matter of years. For example, she shift from the Pleistocene period (glacial she shift from the Pleistocene period (glacial period) to today’s Holocene period occurred in period) to today’s Holocene period occurred in less than 5 years.less than 5 years.

What do scientists measure to determine when What do scientists measure to determine when seasons occurred? seasons occurred? Answer: Scientists use Answer: Scientists use lasers to measure the concentration of dust lasers to measure the concentration of dust particles in the ice core.particles in the ice core.

Describe what is seen and can be interpreted by Describe what is seen and can be interpreted by the image of an ice core analysis. the image of an ice core analysis. Answer: Answer: Based on the thickness of the bands scientists Based on the thickness of the bands scientists can determine heavy or light snowfall amounts.can determine heavy or light snowfall amounts.

Continental Drift/PangeaContinental Drift/Pangea

PangeaPangea- - Scientists Scientists

believe today’s believe today’s continents once continents once existed as one existed as one

“supercontinent” “supercontinent” named Pangea. named Pangea.

Pangea animation

Biological Evolution…evidence of Biological Evolution…evidence of continental driftcontinental drift

Why do you think scientists believe that the Why do you think scientists believe that the continents were once one big landmass? continents were once one big landmass?

Answer: The shape of the continents seem to fit Answer: The shape of the continents seem to fit together like a puzzle. Also, fossils of living together like a puzzle. Also, fossils of living things found in one location can be found in things found in one location can be found in another distant location across the ocean.another distant location across the ocean.

What might have caused this landmass to drift What might have caused this landmass to drift apart? apart?

Answer: Movement of tectonic plates.Answer: Movement of tectonic plates.