ROCK ON!ROCK ON!Introduction to the world Introduction to the world directly beneath our feetdirectly beneath our feet

Why bother to study rocks?Why bother to study rocks?

Three reasons…Three reasons…

To find and utilize To find and utilize natural resourcesnatural resources

Prepare for and Prepare for and maybe prevent maybe prevent natural disastersnatural disasters

Learn about Learn about earth’s natural earth’s natural historyhistory

Natural Natural ResourcesResources CoalCoal PetroleumPetroleum GravelGravel UraniumUranium All metals All metals

used in used in constructionconstruction

AquifersAquifers

EarthquakesEarthquakes VolcanoesVolcanoes LandslidesLandslides Tsunami’sTsunami’s Sink HolesSink Holes Foundation Foundation

ProblemsProblems

Understand Understand DisastersDisasters

Earth’s Earth’s HistoryHistory

All rocks tell All rocks tell an individual an individual story about story about their pasttheir past

If we look and If we look and listen closely, listen closely, we can gain we can gain knowledge of knowledge of our planet’s our planet’s historyhistory

Three basic rock typesThree basic rock types

We classify rocks into three categoriesWe classify rocks into three categories

These categories are distinguished by how These categories are distinguished by how each rock type is formedeach rock type is formed

Igneous Igneous RocksRocks

MetamorpMetamorphic Rockshic Rocks

SedimentSedimentary Rocksary Rocks

The Three Rock TypesThe Three Rock Types

IgneousIgneous – Rocks Born of Crystallized – Rocks Born of Crystallized Fiery Molten Magma or LavaFiery Molten Magma or Lava

SedimentarySedimentary – Rocks Born of Layered – Rocks Born of Layered Water or Wind DepositsWater or Wind Deposits

MetamorphicMetamorphic – Rocks Born of a – Rocks Born of a Change Deep Within the Earth Change Deep Within the Earth

Magma or Lava….which is it?Magma or Lava….which is it?

MagmaMagma – hot – hot molten rock that molten rock that is beneath the is beneath the surface of the surface of the earthearth

LavaLava – hot molten – hot molten rock that has rock that has reached the reached the surface of the surface of the earthearth

How does an Igneous Rock Form?How does an Igneous Rock Form?

CrystallizationCrystallization – the solidifying of magma – the solidifying of magma either at depth or on the exposed surface either at depth or on the exposed surface of the earthof the earth

The weather takes its tollThe weather takes its toll WeatheringWeathering – rocks – rocks

exposed at the surface exposed at the surface undergo disintegration undergo disintegration and decomposition from and decomposition from natural forcesnatural forces

Water, wind, glaciers, Water, wind, glaciers, waves, heat, etc…waves, heat, etc…

All these forces will All these forces will break down rocks and break down rocks and transport the smaller transport the smaller broken down piecesbroken down pieces

These broken down These broken down pieces are now called…pieces are now called…

SEDIMENTSSEDIMENTS

SedimentsSediments – the eroded particles of – the eroded particles of rock that have been transported rock that have been transported away from the original rockaway from the original rock

Where’d my sediments go?Where’d my sediments go?

LithificationLithification – literally means – literally means “conversion into a rock”“conversion into a rock”

Lithification is when compacted and Lithification is when compacted and cemented sediments get buried and cemented sediments get buried and formed into a new rockformed into a new rock

Hence, Hence, sedimentary rockssedimentary rocks

More pressure is applied due to the addition of overlying layers

Sediment grains are fused and cemented together as the water content is reduced

Check out all these sedimentary layersCheck out all these sedimentary layers

Who dug up these buried rocks?Who dug up these buried rocks?

Two things can happen to Two things can happen to sedimentary rocks:sedimentary rocks:

They either get exposed at the They either get exposed at the surface as sedimentary rocks for us surface as sedimentary rocks for us to find, or…to find, or…

They continue to get buried deeper They continue to get buried deeper and deeper within the earth’s crustand deeper within the earth’s crust

How low can you go?How low can you go?

What happens when rocks get buried What happens when rocks get buried very, veryvery, very deep? deep?

The intense The intense heatheat and and pressurepressure of of deep burial will ultimately change deep burial will ultimately change the rocks into something newthe rocks into something new

Metamorphosis Metamorphosis

Metamorphic RockMetamorphic Rock – a rock that has – a rock that has been changed from its original been changed from its original parent rock to a new form due to parent rock to a new form due to intense heat and pressureintense heat and pressure

And if you want to go even deeper?And if you want to go even deeper?

Rocks that reach depths where the Rocks that reach depths where the heat is extreme enough will turn heat is extreme enough will turn back into molten rock material... back into molten rock material...

We have come full circleWe have come full circle

Time, we need more timeTime, we need more time

All the processes of the rock cycle All the processes of the rock cycle happen over incredible time spanshappen over incredible time spans

We cannot see the entire cycle in We cannot see the entire cycle in action, it takes much too longaction, it takes much too long

We see the results of different stages We see the results of different stages of the cycle of the cycle

Evidence for the cycle is found Evidence for the cycle is found everywhere, in every rockeverywhere, in every rock

What Cycle are we Talking about?What Cycle are we Talking about?

ROCK CYCLEROCK CYCLE – The series of – The series of geologic processes that forms geologic processes that forms igneous, sedimentary, and igneous, sedimentary, and metamorphic rocks and then metamorphic rocks and then breaks them down only to form breaks them down only to form new rocks again at a later time new rocks again at a later time and placeand place

THE ROCK CYCLETHE ROCK CYCLE

ROCK CYCLE with ROCK CYCLE with DiagramsDiagrams

To Review:To Review: There are 3 main There are 3 main

reasons to study reasons to study rocksrocks

There are 3 rock There are 3 rock types: igneous, types: igneous, sedimentary, & sedimentary, & metamorphicmetamorphic

Magma & Lava are not Magma & Lava are not quite the same thingquite the same thing

Erosion must occur to Erosion must occur to form sedimentsform sediments

Deposition occurs to Deposition occurs to form sedimentary form sedimentary rocksrocks

Heat & Pressure Heat & Pressure form metamorphic form metamorphic rocksrocks

The Rock Cycle is The Rock Cycle is not just a one way not just a one way streetstreet

There are varying There are varying paths, and rocks can paths, and rocks can reform or skip whole reform or skip whole sections of the cyclesections of the cycle

Geologic processes Geologic processes take incredible take incredible amounts of timeamounts of time