Chapter 4- Rocks Earth Science White lava rock

Bell Work Lesson 4.1 Rock- Natural, solid mixture of minerals/grains Grain- What mineralogists call the fragments that make up a rock Texture- The grain size and the way the grains fit together Magma- Molten or liquid rock underground Lava- Molten rock that erupts on Earth’s surface Sediment- Rock material that forms where rocks are broken down into smaller pieces or dissolved in water as rocks erode Rock cycle- The series of processes that change one type of rock into another type of rock

Rocks A natural, solid mixture of minerals or grains Grain= fragments that make up rock Mineral crystals, broken bits of minerals or rock fragments Can contain remains of organisms or volcanic glass Closeup of the sample above, showing discrete grains of olivine, pyroxene, opaques, and plagioclase.

How to classify rocks? Two important observations: Texture Composition

Texture The grain size and the way the grains for together Look at the size of the minerals or grains Look at the arrangement of the minerals or grains What is the overall feel of the rock?

Composition Classified by the minerals or grains present in a rock Can tell a geologist where the rock formed Certain minerals can suggest rock formed under extreme temperature or pressure

Three major rock types Based on how they form Three types: Can determine where they formed based on the characteristics Three types: Igneous Sedimentary Metamorphic

Igneous rock When magma or lava cools and crystallizes, it creates this kind of rock. Magma= molten or liquid rock underground Lava= molten rock that erupts on Earth’s surface The crystals that grow form the grains of the rock Can form in different environments: Subduction zones, mid-ocean ridges, hot spots (lots of volcanoes) A lithosphere (Ancient Greek: λίθος [lithos] for "rocky", and σφαῖρα [sphaira] for "sphere") is the rigid,[1] outermost shell of a rocky planet, and can be identified on the basis of its mechanical properties. On Earth, it comprises the crust and the portion of the upper mantle that behaves elastically on time scales of thousands of years or greater.

Igneous rock cont’d

Sedimentary rock Sediment: rock material that forms where rocks are broken down into smaller pieces or dissolved in water as rocks erode Sediment, mineral crystals, remains or plants and animals are building blocks of sedimentary rock

Sedimentary rock cont’d Rock forms where sediment is deposited (added to a landform) Examples of where sediment is deposited: Rivers/streams, deserts, valleys Loose sediment will someday turn into rock Examples of where sedimentary rocks can be found: mountain valleys, along river banks, beach etc.

Metamorphic rock Rocks that are exposed to extreme temperature and pressure can change to metamorphic rock Can happen along plate boundaries Can also happen if rock is exposed to some chemical fluids Minerals change AND texture changes when the rock changes into metamorphic rock. Grains can look bent or twisted

Metamorphic rock cont’d Can form from ANY rock (including other metamorphic rock) Limestone (sedimentary rock) metamorphoses into marble Granite (igneous rock) metamorphoses into gneiss.

Rock Cycle The series of processes that change one type of rock into another type of rock Rocks are changing all the time Slowly Because of forces within Earth and on Earth’s surface Example: 1- Lava forms igneous rock; 2- the rock is exposed to Earth’s surface and is eroded by water to form sediment; 3- the sediment cements together to form sedimentary rock.

Rock cycle cont’d Some processes can only occur under Earth’s surface Extreme pressure and temperature (and melting) Some rocks that are made under Earth’s surface change when uplifted to Earth’s surface What changes can happen once on surface? Weathering, erosion, deposition, compaction, cementation. Uplifted= techtonic process that forces these rocks onto Earth’s surface

HOMEWORK Ch4 L.1 Vocabulary words on flash cards Outline Lesson 1 MEMORIZE THEM FOR QUIZ Outline Lesson 1 Lesson Review questions P. 116 #1-8 QUIZ!!!!

LaunchLab p.111 Obtain a rock sample Examine the rock with/without a magnifying glass Describe rock in detail Color Texture Anything weird/cool in it? Any minerals/grains you can see? WRITE YOUR NAME ON PAPER AND TURN IT IN

Ch4 L.2 Igneous Rocks

Bell Work Ch4 L.2 Extrusive rock: When volcanic material erupts and cools and crystallizes on Earth’s surface Volcanic Glass: Rock that forms when lava cools too quickly to form crystals Intrusive Rock: Igneous rocks that form as magma cools slowly underground

Essential questions: How do igneous rocks form? What are the common types of igneous rocks?

Launch Lab p.119 Observe what happens when I drop hot, melted sugar into your beaker of water. One time slowly One time quickly Record what happens What is the difference between the two? WRITE YOUR FULL NAMES ON IT AND TURN IT IN. WORK IN PAIRS.

Igneous rock formation Lava cools to become igneous rock Happens quickly when exposed to air Darker color where already started to crystallize Magma cools slowly below Earth’s surface Can become exposed to the Earth’s surface eventually after wind, water and other factors wear away the ground on top of it http://www.science-art.com/image/?id=2907#.VGin6RxD53c pic

Extrusive rocks When volcanic material erupts and cools and crystallizes on Earth’s surface Lava and ash solidify to form this Happens fast= not enough time for crystals to grow Fine-grained texture http://en.wikibooks.org/wiki/High_School_Earth_Science/Igneous_Rocks

Extrusive rocks cont’d Volcanic glass= rock that forms when lava cools too quickly to form crystals Example: Obsidian (both pictures) http://en.wikibooks.org/wiki/High_School_Earth_Science/Igneous_Rocks http://geology.com/rocks/obsidian.shtml

Extrusive rocks cont’d Gases can be trapped in magma Magma moves towards the surface Gases can cause eruptions (think of carbonation in soda) Gas-rich lava erupts and gases escape Forms special igneous extrusive rocks Example: pumice Why do you think pumice has all those holes? http://en.wikipedia.org/wiki/Pumice Pumice + scoria are cousins but scoria doesn’t float, it’s more dense than pumice

Mini Lab p.120 I NEED 3 VOLUNTEERS Each Volunteer will receive 1 beaker and 1 watch glasse Fill the three beakers with water One filled with HOT water One filled with WARM water One filled with COLD water Place the beakers in the back of the room Place one watch glass on each of the beaker MAKE SURE THERE IS ENOUGH WATER SO IT IS TOUCHING THE WATCH GLASS I will come around and pour 3mL of water with dissolved Epsom salt. We will look at the crystals TOMORROW.

Intrusive rock Igneous rocks that form as magma cools slowly underground Large, well-defined crystals can form Random arrangement of crystals Crystals interlock like a jigsaw puzzle Typical characteristics: Large crystals Random arrangement http://gamediv1.weebly.com/igneous-rocks.html

Igneous rock identification Texture: Crystal size Small + hard to see (sometimes only with magnifying lens)= extrusive Large enough to see with interlocking arrangement= intrusive http://geology.com/rocks/igneous-rocks.shtml

Igneous rock identification Composition: Silica content (estimate based on color of minerals) Darker colored minerals= usually less silica and more magnesium and iron Examples: Perodite contains minerals olivine and pyroxene Lighter colored minerals= usually more silica Examples: rhyolite contains minerals quartz and feldspar

Igneous rock identification

Igneous rock identification http://faculty.chemeketa.edu/afrank1/rocks/igneous/igclass.htm

HOMEWORK Ch4 L.2 Vocabulary words on Flash Cards Outline Ch4 L.2 MEMORIZE FOR QUIZ Outline Ch4 L.2 Lesson review questions Page 123 Questions 1-10 QUIZ!!!!!

Ch4 L.3 Sedimentary Rocks

Bell Work Ch4 L.3 Compaction: the weight from layers of sediment forces out fluids and decreases space between grains Cementation: Minerals dissolved in water crystallize between sediment grains Clastic rock: Made up of broken pieces of minerals and rock fragments Clast: the broken pieces of minerals and rock fragments that form clastic rock. Chemical rock: form when minerals crystallize directly from water. Biochemical rock: Sedimentary rock that was formed by organisms or contains the remains of organisms

Essential questions How do sedimentary rocks form? What are the three types of sedimentary rocks?

Mini Lab Follow up What do you think crystals will look like? Write down your predictions. THEN go to the back of the room and observe the crystals formed from the three environments Hot, Warm, Cold Record your observations How are the crystals different? Prediction (hot) Prediction (warm) Prediction (cold) Observation (hot) Observation (warm) Observation (cold)

Sedimentary rock formation Can form in different environments Water and air can break down rock Also can transport rock fragments to new locations Sediment deposited in layers Gets thicker over time Compaction: the weight from layers of sediment forces out fluids and decreases space between grains http://krupp.wcc.hawaii.edu/BIOL101/present/lcture13/sld005.htm

Sedimentary rock formation cont’d Compaction can lead to cementation Minerals dissolved in water crystallize between sediment grains Holds grains together Examples of minerals that cement: quartz, calcite, and clay http://www.gcsescience.com/rk10.htm

Sedimentary rock identification Classified according to how they form Deposited, compacted then cemented Evaporation when minerals crystallize from water When organisms remove minerals from water to make shells or skeletons

Clastic Sedimentary Rocks Made up of broken pieces of minerals and rock fragments Clasts= broken pieces Identify according to clast shape and size Can’t use shape alone Can be as big as a car or as small as a grain of flour Shape helps determine environment where it formed Small, gritty sediment= typically in calm environments (sea floor, bottom of lake) Large sediment= can be moved by oceans waves, fast flowing rivers

Chemical sedimentary rock Dissolved minerals can be carried from rivers to the ocean (contribute to saltiness) Water can be saturated with dissolved mineral and minerals can crystallize out of the water Chemical rocks form when minerals crystallize directly from water.

Chemical sedimentary rock cont’d Examples: rock salt (halite), rock gypsum, limestone Interlocking crystalline texture (similar to igneous rocks) Generally composed of one dominant mineral= uniform in color Different from igneous rocks (generally many minerals)= multi-colored http://geology.com/rocks/sedimentary-rocks.shtml

Biochemical sedimentary rocks Sedimentary rock that was formed by organisms or contains the remains of organisms Most common= limestone Organisms make shells from dissolved minerals Organism dies and shells settle on the floor= forms part of rock If contains fossils= fossiliferous http://www.geologyclass.org/sedimentary_concepts.htm

Biochemical sedimentary rocks Carbonate rock= contains carbon and oxygen Will fizz when add hydrochloric acid Limestone is an example Not all biochemical rocks are carbonates Diatomite looks like limestone but doesn’t fizz with HCl Coal Composed of remains of plants and animals Buried and compressed to eventually form sedimentary rock http://quizlet.com/10102299/science-olympiad-sedimentary-rocks-flash-cards/

Common Chemical and Biochemical Rocks

Mini Lab p. 128 Use grains of sedimentary rocks to identify the environment where they likely formed What to look for? (Write this down for each) Grain size Grain shape Have you seen something similar before? Guess: in what environment was each formed? Grain Size? Grain Shape? Seen this before? Environment guess #1 #2 #3 #4

HOMEWORK Vocabulary words on Flash Cards Ch4 L.3 Outline Memorize for quiz Ch4 L.3 Outline Lesson review questions Page 130 Questions 1-10 QUIZ

Ch4 L.4 Metamorphic Rock

Bell Work Ch4 L.4 Metamorphism: any process that affects the structure or composition of a rock in a solid state as a result of changes in temperature, pressure or the addition of chemical fluids Plastic deformation: permanent change in shape by bending and folding Foliated rock: metamorphic rock that contains parallel layers of flat and elongated minerals Contact metamorphism: Magma comes in contact with existing rock, its thermal energy and gases interact with the surrounding rock, forming new rock. Regional metamorphism: Formation of metamorphic rock bodies that are hundreds of square kilometers in size

Essential questions How do metamorphic rocks form? How do types of metamorphic rocks differ?

Metamorphic rock formation Metamorphism: any process that affects the structure or composition of a rock in a solid state as a result of changes in temperature, pressure or the addition of chemical fluids. Most metamorphic rocks form deep within the Earth’s crust. Why? High temperature and pressure http://kmapes.weebly.com/ap-notes---rock-cycle-and-formation.html

Metamorphic rock formation Do not crystallize from magma Different from igneous rocks Do not result from erosion and deposition Different from sedimentary rocks Rocks change shape because of extreme temperature and pressure Bend and twist into wrinkly layers http://www.sciencekids.co.nz/sciencefacts/earth/metamorphicrocks.html

Temperature and Pressure Under high temperature and pressure, rocks behave like bendable plastic, they can bend or fold Plastic deformation: permanent change in shape by bending and folding Occurs during uplifting events when techtonic plates collide and form mountains This is how the texture changes http://explanet.info/Chapter02.htm

Temperature and Pressure Parent rock: rock that changes during metamorphism. Temperature depends on composition, between 150-200 degrees Celcius http://www.murraystate.edu/qacd/cos/geo/gsc199/labs/lab11/sedmetparentfoliation.htm Gneiss= pronounced “nice”

Metamorphic rock identification Classified into two groups based on texture (foliated and nonfoliated) Changes in pressure can align minerals to form layers Can look like clastic sedimentary rock BUT presence of crystalline minerals in metamorphic rock differentiate it from sedimentary rock Rock can also have blocky, interlocking crystals that are uniform in color http://www.minsocam.org/msa/collectors_corner/id/rock_key.htm#metamorphic

Foliated rocks Contain parallel layers of flat and elongated minerals Layering is because of uneven distribution of pressure during metamorphism Examples: phyllite and gneiss http://geology.com/rocks/metamorphic-rocks.shtml

Nonfoliated rocks Metamorphic rocks that have mineral grins with a random, interlocking texture No obvious alignment Individual crystals look blocky and approximately equal in size Minerals are generally uniform in color Different from igneous rock that is generally multicolored (like granite) Examples: amphibolite and quartzine Amphibolite Quartzine (morph from sandstone= primarily quartz)

Contact metamorphism Magma comes in contact with existing rock, and its thermal energy and gases interact with the surrounding rock, forming new metamorphic rock. Can increase crystal size or form new minerals and change rock http://en.wikipedia.org/wiki/Metamorphic_rock

Regional metamorphism Formation of metamorphic rock bodies that are hundreds of square kilometers in size Changes in temperature and pressure and presence of chemical fluids Can create entire mountain range of metamorphic rock Examples: Himalayas (Asia), Appalachian Mountains (US) Act on large volumes of rock http://mtweb.mtsu.edu/cribb/1030metamorphicrocks.html

Metamorphic rocks http://geologycafe.com/images/metamorphic_rocks.jpg

Rock identification lab Crystal size? Color? Arrangement? Special? Igneous Small (extrusive), large (intrusive) Multi-colored Interlocking (intrusive) Light (silica), dark (Fe3+,Mg2+) Sedimentary See pebbles or grains but not really crystals Uniform color Varies, can have layering Fossils? Carbonate? Metamorphic Yes Varies, can be uniform Nonfoliated (blocky, interlocking crystals=uniform color) Folliated (parallel layers of elongated minerals) Crystals visible? Single color or multi-colored? Uniform size grains? Layers? What kind of rock? Rock Identification? #1 #2 #3 #4

HOMEWORK Ch4 L.4 Vocabulary words on Flash Cards Outline Ch4 L.4 MEMORIZE FOR QUIZ Outline Ch4 L.4 Lesson review questions Page 137 Questions 1-8 QUIZ!!!!