Mrs. Harriss slides:IgneousMetamorphicSedimentary

Earth ScienceIgneous Rocks

TodayIgenous rocksIntrusiveExtrusiveCrystal sizeTextureComposition

Igneous RockA rock made from the solidification of cooled magmaRocks melt = magmaMagma cools = igneous rock

What makes rock melt?

Making MagmaTemperature 1,000-2,000 FoDifferent minerals melt at different temperatures (like cheeses)

PressureHigher pressure requires higher temperatures to melt

Water and/or Carbon DioxideThese lower the pressure which lowers the temperature required to melt

Partial MeltingCertain minerals will melt before others based on their chemical compositionLike having butter, chocolate, and cheese in a pot what melts first?

Types of IgneousIntrusiveForm below the surface

ExtrusiveForm on the surface

Cool It!Rate of cooling determines size of the crystals

Slow = largeIntrusive

Fast = smallExtrusive

Ever made rock candy?

Slow CoolerLarge crystals

Course texture

Intrusive or extrusive?

Quick CoolerSmall crystals

Fine texture

Intrusive or extrusive?

Can it be both?

Absolutely!When magma cools quickly at first and then slower it makes both crystal sizes.

This is called porphyritic

Other texturesGlassyVesicular

IntrusiveMagma pushed into existing rock and cools

Intrusive

ExtrusiveLavaMagma on Earths surface

PyroclastsAshes to rocks, erupted

Pyroclastic flowHot, dry ash, rock, and gasses

CompositionFelsicLots of silicaLight in colorMaficIron & magnesiumDarker in color(sometimes has ferromagnesium minerals)Intermediate rocks are in between felsic and mafic.

VocabTextures:FineCoursePorphyriticGlassyVesicularCompositionFelsicMaficIntermediate

What do you callA rock has cooled quickly and is dark in color

What do you callA rock has cooled quickly and is dark in color

What do you callA rock has cooled slowly and is light in color

What do you callA rock has cooled slowly and is light in color

What do you callA rock has cooled fast then slow and is light and dark in color

What do you callA rock has cooled fast then slow and is light and dark in color

This week6-2 quizUnit 6 discussionUnit 6 assignment7-2 quiz7-2 quiz

Next classMetamorphicSedimentary

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*Metamorphic RockWhat is it?

When does it happen?

Where do they occur?

Types of metamorphism

*Metamorphic Rock

Meta & morph = change shape

Rocks changed by heat, pressure, and fluids

*Making Metamorphic RockTwo rules for changes:

Below the surface

Solid state

*Metamorphic HeatAt least 250 Co

Geothermal gradientEarth gets hotter by 25 Co for every km down

Magma = Contact metamorphism

Changes bonding structure

*Metamorphic Pressure

Pressure: need 2 kilobars

Depth Add a kbar for every 3-ish km down

Convergent and transform boundaries = regional metamorphism

Strains bonds, some break, more compact structure

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*Metamorphic Chemical Fluid

Fluid carrying dissolved ions

Magma chamber

Ridge vents

Changes minerology

*After metamorphismRecrystallizationCrystal size changes

CompactionPore space reduced

Foliation (not always)Parallel platy grains

*Slate

*Schist

*Gneiss

Sedimentary RockRocks formed by one of 3 processes:Physical processesPlants and animalsChemical processes

Sedimentary: Physical ProcessFormed by the physical breakdown of pre-existing rocksEroding agents like water, wind, ice

Transported (load), deposited, lithification (next slide)

Clastic rocks

Lithification- sediment changes to rock

Compaction- increased pressure & temp, removes water

Cementation- any spaces become filled by minerals out of solution

Mineralogic change- some break down, others change

Sedimentary: Physical Process

Sandstone

Sedimentary: Plants & AnimalsMade of plants and/or animalsExamples:Shells, bacteria, compressed plants

Organic sedimentary rock

Oil Shale- Tropical plants, compressed

Stromatolites- made by algae

Sedimentary: Chemical ProcessRocks made of crystals from solutionChemicals in water, water evaporates, crystals growCalled evaporite

Chemical Sedimentary Rocks

Halite- a.k.a. salt

Fossils

Looking Ahead:Unit 7 AssignmentsPart 1 is a unit testPart 2 is a short report

Next week: ores & mining