Learning ObjectivesLearning Objectives1. I can list and identify the 3 types of

rocks and explain how they are created.

2. I can describe how the surface of the Earth is shaped by building up, weathering and erosion.

3. I can identify the 3 layers of the Earth and their features.

Learning ObjectivesLearning Objectives

4. I can explain how and why plates move, the effects of their movement, and the difference between convergent, divergent, and transform plate boundaries.

5. I can list and describe the three types of volcanoes.

6. I can use evidence such as layers of fossils and sediments, current landforms, and tectonic movements as evidence of geologic processes that have changed the Earth’s surface.

The The RockRockCycleCycle

Images from Geology.com unless otherwise Images from Geology.com unless otherwise notednoted

What are Rocks?What are Rocks?

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

• Rocks change over time through the rock cycle

Rock TypesRock Types

• Rocks can be classified into groups just like living organisms.

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

• The three main groups are:

IGNEOUS SEDIMENTARYMETAMORPHIC

The Rock Cycle

                                             melting

Another look at the Rock CycleAnother look at the Rock Cycle

Igneous RocksIgneous Rocks

• Igneous rocks form when magma or lava cools and becomes solid

• Magma is a mixture of

many minerals

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

Magma and LavaMagma and Lava

• Magma is melted rock inside of the Earth

• Lava is magma that reaches the surface.

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

Igneous RocksIgneous Rocks

Intrusive Igneous Rocks: Rocks that are made from magma (inside the earth)

Extrusive Igneous Rocks: forms when magma erupts onto the Earth’s surface (lava), cools quickly with very small or no crystals formed

http://www.windows.ucar.edu/tour/link=/earth/geology/ig_intrusive.html&edu=high&fr=t

Intrusive Igneous RocksIntrusive Igneous Rocks

Phanertic crystals – large crystals formed in intrusive igneous rocks

Crystals form because the rocks cool slowly enabling the large crystals to grow

http://www.windows.ucar.edu/tour/link=/earth/geology/ig_intrusive.html&edu=high&fr=t

Igneous RocksIgneous Rocks

Felsic

Mafic

Coarse-Grained

Fine-Grained

Granite

Gabbro Basalt

Rhyolite

Metamorphic RocksMetamorphic Rocks

• Metamorphic rocks- Metamorphic rocks- Heat and Pressure form Heat and Pressure form Metamorphic RockMetamorphic Rock

• Occurs deep within the Occurs deep within the Earth (not on the Earth (not on the surface)surface)

Metamorphic RocksMetamorphic Rocks

• Igneous and sedimentary rocks can form into metamorphic rocks when under a lot of heat and pressure within the earth

SedimentsSediments

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

Sediments are pieces of rock, minerals, and organic remains.

Sediments are formed by weathering.

Due to erosion sediments are moved from one place to another

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

Sedimentary RocksSedimentary Rocks

• Sedimentary rock is formed when layers of sediments become compacted and cemented together

GeodesGeodes

• Geodes are created in the hollow areas of soil such as animal burrows or tree roots. They are also formed in the bubbles in volcanic rock.

• Water filters through the rock bringing in minerals which harden into an outer shell creating the geode

Weathering is the breaking down of rocks and other materials on the earth’s surface

Weathering

Two Types of WeatheringTwo Types of Weathering

Mechanical WeatheringMechanical WeatheringChemical WeatheringChemical Weathering

Mechanical WeatheringMechanical Weathering

• No change in the rock’s chemical composition only physical.

• Examples:– Temperature– Ice Wedging– Abrasion– Wind– Root Pry

Chemical WeatheringChemical Weathering

• Changes the chemical composition of the rock

• Examples: – Acid – Oxidation (causes rust)– Plant Acid

ErosionErosion

• Erosion- The process by which weathered rock and soil particles are movedmoved from place to place– Gravity– Glaciers– Wind– Surface Water / Running Water– Ocean Shoreline / Ocean Waves

The Layers of the Earth

© Copyright 2006.  M. J. Krech. All rights reserved.

The Three Main The Three Main LayersLayers

• The three main layers are: – Crust – Mantle– Core

• Outer Core• Inner Core

The Four LayersThe Four Layers • Crust - the thin layer you live on

• Mantle - the ability to flow like liquid.

• Outer core - made of liquid iron and nickel

• Inner core - solid because of temperatures and pressure are great

PangaeaAn ancient supercontinent that scientists

believe existed from about 200 to 300 million

years ago.

How is this possible?!?!?How is this possible?!?!?

Geological Changes—3:25

Continental DriftContinental Drift

• Alfred Wegener was the 1st scientist to come up with the idea of “continental drift”

• His idea was that the continents slowly moved away from each other.

• This supercontinent was called Pangaea.

o Minerals, fossils, and mountains, on now different continents, match if the continents were together

Continental Drift Continental Drift EvidenceEvidence

The Mystery of Brachiosaurus (~3 min)

The lithosphere is divided into a number of large and small plates and the plates are floating on the mantle.

Plate Tectonics TheoryPlate Tectonics Theory

Lithosphere = the Earth’s crust plus the upper portion of the mantle layer

Plate BoundariesPlate Boundaries

Plate BoundariesPlate Boundaries

Divergent boundary: Divergent boundary: o Plates are moving away from

each othero Mid-ocean ridges are created

and new ocean floor plates are created called Seafloor Spreading

Seafloor Spreading Theory:

• Ocean floors are moving like broad conveyor belts

• Forms new crust through the upwelling of magma

Divergent boundary: Divergent boundary:

Plate BoundariesPlate Boundaries

Convergent BoundaryConvergent Boundary: plates are moving toward each other and are colliding (3 types)

Convergent Boundaries Convergent Boundaries Create:Create:

Subduction zone-Places where

plates are moving toward each

other and one plate melts under

the other and the magma moves

upward to form volcanoes.

• Create subduction zones,

• Trenches• Create near Create near

coast volcanoescoast volcanoes– Example: Example:

Cascade Cascade MountainsMountains

1. When Ocean Plates collide with 1. When Ocean Plates collide with Continental PlatesContinental Plates

2. When Ocean plates collide with 2. When Ocean plates collide with other Ocean platesother Ocean plates

– Island arcs are created (a pattern of volcanic islands created

from a subduction zone that is located off the coast)Example: Japan and Philippines

• MountainMountain rangesranges are created – (example: Himalayan

Mountains)

3. When a Continental plate collides 3. When a Continental plate collides with another Continental platewith another Continental plate

What About Hawaii?What About Hawaii?

•Do you see any plate boundaries there?

Hawaii

What About Hawaii?What About Hawaii?• Hawaiian Volcanoes

form from HOT HOT SPOTSSPOTS

Hot spots are Hot spots are places where places where the the mantle is mantle is unusually hotter unusually hotter than other parts of than other parts of the mantle the mantle or an or an unusually weak unusually weak (thin) part of the (thin) part of the crust…(we’re not crust…(we’re not sure why)sure why)

Magma that may originate in the mantle or outer core will move upward, breaking the surface and forming a volcano, they are independent of plate boundaries and a chain of volcanoes may form as the plate moves across a hot spot.

Hot SpotsHot Spots

(Examples: Hawaiian Islands and Yellowstone National Park)

Hot SpotsHot Spots

Transform Fault BoundaryTransform Fault Boundary

Plates are neither moving toward nor away from each other, they are moving past one another.

Transform Fault BoundaryTransform Fault Boundary

The plates may move in opposite directions or in the same directions but at different rates and frequent earthquakes are created (example: San Andreas FaultSan Andreas Fault)

San Andreas FaultSan Andreas Fault

NOTE: o Plates are destroyed as fast as

they are created (2 ways)

o Plates may be subducted and melted or may push be pushed upward to form mountains

Why is Earth not getting bigger or Why is Earth not getting bigger or smaller?smaller?

Convection currents occur within the mantle

The up-welling leg of the current creates a divergent boundary which produces midocean ridges

Convection CurrentsConvection Currents

Convection CurrentsConvection Currents

Seafloor SpreadingThe down-welling leg of the current creates one type of convergent boundary that results in trenches and a subduction zone

Volcano:

an openingopening in the earth’s surface through which lava, hot gases, and rock fragments erupterupt

Introduction to volcanoes

A crater is formed when the volcano sides are higher than the vent forming a depression

Origin of VolcanoesOrigin of Volcanoes

Types of VolcanoesTypes of Volcanoes

• Shield

• Composite (Strato-)

• Cinder

• (Super volcanoes)

Types of Volcano MountainsTypes of Volcano Mountains

Shield Volcanoes: Large base, gentle slope, lava rock

layers A few miles high Life span of a million years or more The lava is hot, low viscosity

(thinner, more watery), often basaltic.

Usually gentle, slow eruptions Example: Hawaiian Islands

Shield volcanoesShield volcanoes

• Mauna Loasee it’s low, broad shape

Cinder cones, the burps of the Cinder cones, the burps of the volcanic familyvolcanic family

• Relatively small in size, hundreds to 2,000 feet tall

• Usually steep sided and cone shaped.

• Found on the outskirts of all types of stratovolcanoes and shield volcanoes

Composite VolcanoesComposite Volcanoesaka Strato-Volcanoesaka Strato-Volcanoes

• Typically large, steep sided, up to 8,000 ft above their bases.

• Have a crater at the summit which contains a central vent or a clustered group of vents.

Composite volcanoesComposite volcanoes

• Found near “subduction zones.”– Denser oceanic plates sliding beneath

continental plates– Oceanic crust melts, rises through continental

crust, creates chain of volcanoes

Composite Volcano EruptionsComposite Volcano Eruptions

• Very violent, explosive and BIG!!!

• Entire sides of mountain gone in a few seconds.

Historically cool… Mt. VesuviusHistorically cool… Mt. Vesuvius

A whole dead city, entombed in ash!A whole dead city, entombed in ash!

Now onto supervolcanoesNow onto supervolcanoes

• Hold on to your hats, it’s the end of the world!

What are super volcanoes?What are super volcanoes?

• Super volcanoes are those that have extremely high levels of silica

• This makes for crazy viscous (thick & “sticky”) lava, and HUGE eruptions

• The lava is so viscous it doesn’t even allow for a cone shaped volcano

YellowstoneYellowstone

• Created by a hot spot

• Evidence from the Snake River Valley of past eruptions and calderas

• So explosive it clears away enough crust that low viscosity basalt can sometimes come up

• Can change the course of geologic history

What are the consequences of it What are the consequences of it blowing?blowing?

• We could hear it blow in Washington• Ash goes into the layer of atmosphere

called the stratosphere, which will remain and block sunlight

• The entire Earth would cool, potentially causing an ice age

• If no ice age, definitely crops would die and food shortages would occur

• People are gonna die!