Rocks, what do they mean Rocks, what do they mean to you?to you?

• Some rock formations are famous Some rock formations are famous and when they disappear, their and when they disappear, their legends don’tlegends don’t

RocksRocks •The ones The ones found found

in the in the

Earth, not Earth, not

in some in some

of your of your heads!!!!heads!!!!

Igneous RocksIgneous Rocks•Also known as “fire rocks”Also known as “fire rocks”•They are formed by the They are formed by the

crystallization of magma or crystallization of magma or lavalava

•Magma is the molten Magma is the molten material found undergroundmaterial found underground

•Lava is the molten material Lava is the molten material found above groundfound above ground

Composition of MagmaComposition of Magma

• Magma is a slushy mix of molten Magma is a slushy mix of molten rock, gases, and mineral crystalsrock, gases, and mineral crystals

• It has the same major elements It has the same major elements that are found in the earth’s that are found in the earth’s crust: Ocrust: O22, Si, Al, Fe, Mg, Ca, K, and , Si, Al, Fe, Mg, Ca, K, and NaNa

• Magma is classified according to Magma is classified according to the amount of Si it containsthe amount of Si it contains

• Rhyolitic (70%), Andesitic (60%), Rhyolitic (70%), Andesitic (60%), and Basaltic (50%)and Basaltic (50%)

Classification of Igneous Classification of Igneous RocksRocks

• Igneous rocks are classified Igneous rocks are classified according to their composition according to their composition and textureand texture

• Texture refers to the minerals of Texture refers to the minerals of which rocks are formed, the which rocks are formed, the shape, size, arrangement, and shape, size, arrangement, and distribution of the mineralsdistribution of the minerals

• Ex: light colored rocks are rich in Ex: light colored rocks are rich in quartz, dark colored rocks might quartz, dark colored rocks might be rich in olivinebe rich in olivine

There are two types of There are two types of igneous rocks:igneous rocks:

- extrusive are fine extrusive are fine grained (small grained (small crystals) that cool crystals) that cool on the surface of on the surface of the Earth the Earth

- (obsidian, (obsidian, pumice, basalt)pumice, basalt)

- intrusive are - intrusive are coarse coarse grained grained (large (large crystals) that crystals) that cool slowly cool slowly underground underground from plutonsfrom plutons

(granite)(granite)

Mineral CompositionMineral Composition

• Felsic rocks are Felsic rocks are high in silicon high in silicon and light and light colored. Ex: colored. Ex: granitegranite

• Intermediate Intermediate rocks have less rocks have less silicon and are silicon and are darker. Ex: darker. Ex: DioriteDiorite

• Mafic rocks are Mafic rocks are low in silicon low in silicon and dark in and dark in color. Ex: color. Ex: gabbrogabbro

• Ultramafic rocks Ultramafic rocks are very low in are very low in silicon and very silicon and very dark in color. dark in color. Ex: peridotite Ex: peridotite and duniteand dunite

Texture of Igneous Texture of Igneous RocksRocks

• Glassy Glassy igneous igneous rocks look rocks look like glass like glass and do not and do not have their have their minerals minerals arranged in arranged in crystalline crystalline formationformation

• Aphanitic or Aphanitic or fined grained fined grained igneous igneous rocks have rocks have crystals crystals present, but present, but they are too they are too small to be small to be seen with the seen with the naked eyenaked eye

• Phaneritic or Phaneritic or coarse coarse grained grained igneous igneous rocks have rocks have crystals that crystals that are about are about the same the same size and size and easily seeneasily seen

• Porphyritic or Porphyritic or mixed grained mixed grained texture texture igneous rocks, igneous rocks, large crystals large crystals embedded in embedded in a field of a field of smaller smaller crystalscrystals

Veins of Igneous RocksVeins of Igneous Rocks

• Pegmatite contains Pegmatite contains very large grained very large grained minerals such as minerals such as lithium and lithium and beryllium, as will as beryllium, as will as some of the most some of the most beautiful crystalsbeautiful crystals

• Kimberlites are rare Kimberlites are rare and can contain and can contain diamondsdiamonds

And on we And on we gooooooooo!gooooooooo!

Sedimentary Rocks

Slowly Built LayersSlowly Built Layers•Sedimentary rocks are Sedimentary rocks are

classified according to the classified according to the origin of the material that origin of the material that they are made fromthey are made from

•ClasticClastic•Organic Organic •ChemicalChemical

ClasticClastic• Clastic Clastic

sedimentary sedimentary rocks are made rocks are made from the from the fragments of fragments of existing rocksexisting rocks

• They are further They are further classified classified according to the according to the size and shape of size and shape of the fragments the fragments they are made ofthey are made of

ConglomeratesConglomerates• These are made from pebbles These are made from pebbles

cemented together with mud, cemented together with mud, clay, or sandclay, or sand

• Over one third is made of pebblesOver one third is made of pebbles

Sandstones• Made from

particles the size of sand

• At least half of the material must be sand to be classified as sandstone

• Grains are cemented together by minerals

• Most common sedimentary rock

ShalesShales• Made from

particles smaller than sand

• Made from small particles of mud and clay

• Most can be split into flat pieces

Organic RocksOrganic Rocks• Organic Organic

sedimentary sedimentary rocks are rocks are made either made either directly or directly or indirectly indirectly from from material that material that was once was once livingliving

LimestonesLimestones• May be May be

produced by produced by the shells of the shells of once living once living organismsorganisms

• Living Living organisms may organisms may produce produce limestone limestone directly as in directly as in coral reefscoral reefs

ChalkChalk• Fine grained limestone made Fine grained limestone made

from microscopic shellsfrom microscopic shells

CoalCoal• Formed Formed

from the from the remains of remains of plants that plants that lived lived millions of millions of years agoyears ago

Chemical RocksChemical Rocks• Formed when Formed when

a sea or lake a sea or lake dries up dries up leaving behind leaving behind large amounts large amounts of mineralsof minerals

• This includes This includes rock salt, rock salt, gypsum, and gypsum, and some some limestonelimestone

The Making of Sedimentary The Making of Sedimentary RocksRocks

• Erosion and weathering of Erosion and weathering of parent rockparent rock

• Transportation of sedimentsTransportation of sediments• Deposition of sedimentsDeposition of sediments• Compaction and cementation of Compaction and cementation of

sedimentssediments• Lithification which turns the Lithification which turns the

sediments into sedimentary sediments into sedimentary rocksrocks

Interesting sedimentary rock Interesting sedimentary rock structuresstructures

Had enough yet?Had enough yet?

Metamorphic RocksMetamorphic Rocks

Metamorphic RocksMetamorphic Rocks• Rocks that are caused by high Rocks that are caused by high

pressure and/or heatpressure and/or heat• They are not completely meltedThey are not completely melted• High temperature and pressure High temperature and pressure

combine to change the texture, combine to change the texture, mineralogy, and chemical mineralogy, and chemical composition of igneous, sedimentary, composition of igneous, sedimentary, and metamorphic rocksand metamorphic rocks

Regional Metamorphic Regional Metamorphic RocksRocks

• Large areas of metamorphismLarge areas of metamorphism

Contact Metamorphic Contact Metamorphic RocksRocks

• Contact with an igneous intrusionContact with an igneous intrusion

Hydrothermal Hydrothermal MetamorphismMetamorphism

• Contact with very hot waterContact with very hot water

Textures of Metamorphic Textures of Metamorphic RocksRocks

• Foliated have wavy layers and bands of Foliated have wavy layers and bands of mineralsminerals

Non-foliated have minerals with blocky Non-foliated have minerals with blocky crystals shapescrystals shapes

Changes to Parent RocksChanges to Parent Rocks• Mineral changes- one mineral changes to another due Mineral changes- one mineral changes to another due

to the high heat and pressureto the high heat and pressure

• Compositional changes- most of the composition of Compositional changes- most of the composition of original rocks doesn’t change, hot liquid can alter the original rocks doesn’t change, hot liquid can alter the mineral and texture which can form valuable ore mineral and texture which can form valuable ore deposits like Au, Cu, Zn, W, and Pbdeposits like Au, Cu, Zn, W, and Pb

GraniteGranite GneissGneiss

LimestoneLimestone MarbleMarble

ShaleShale Slate Slate

SandstoneSandstone QuartziteQuartzite

BasaltBasalt SchistSchist

ShaleShale Mica Schist Mica Schist

Rock HumorRock Humor1.1. What does a rock want to be when it What does a rock want to be when it

gets older?gets older?

2.2. What do you call a dog who collects What do you call a dog who collects rocks?rocks?

3.3. What do you do to a baby rock?What do you do to a baby rock?

4.4. What is a rock’s favorite kind of music?What is a rock’s favorite kind of music?

5.5. Where do rocks sleep?Where do rocks sleep?

6.6. How do rocks wash their clothes?How do rocks wash their clothes?

7.7. What is a rock’s favorite transportation?What is a rock’s favorite transportation?

8.8. What is a rock’s favorite cereal?What is a rock’s favorite cereal?

AnswersAnswers

1.1. A Rock starA Rock star2.2. A RockhoundA Rockhound3.3. Rock itRock it4.4. Rock ‘n RollRock ‘n Roll5.5. BedrockBedrock6.6. On the rock cycleOn the rock cycle7.7. A rocketA rocket8.8. Cocoa pebblesCocoa pebbles

The Grand FinaleThe Grand Finale