1 pp tall earthsciencecombo.dewey.5thgrade
DESCRIPTION
TRANSCRIPT
Four Systems
of
Our Earth
Composition of Earth Earth Has 4 main systems that interact:
Earth’s systems
Atmosphere Hydrosphere Biosphere Geosphere
water life land/rockAir/gases
The Atmosphere– layer of gas that surrounds Earth more commonly known as “air”.
Atmosphere. How do you know its there Is this “air” that surrounds us considered
matter? Does it weigh anything? How do you know?
Think about it and decide on an answer. Talk in groups with the person who sits by
you Be ready to tell the class what you decided
and why.
Weight of the atmosphere Gases are in the
atmosphere. They are things we
learned about in the periodic table: Nitrogen, Oxygen, Carbon Dioxide, Hydrogen
It is matter! Sound can travel through it.
Even though you can’t see them, Atoms make up gases.
Are some atoms bigger than others? Are their atomic weights all the same?
Helium vs. Carbon DioxideDo you think of helium as light and floating or heavy and falling?
Do you think about Carbon Dioxide as light and floating or heavy and falling….think about the gas released from dry ice… does it go up or down?
http://jp.youtube.com/watch?v=F239cINIADs
Composition of Earth Earth Has 4 main systems that interact:
The Atmosphere Mostly Nitrogen and Oxygen Water vapor is responsible for clouds and
precipitation Has layers Protects us from meteors and comets, x-rays,
gamma rays, ultra violet light
The Hydrosphere The Biosphere The Geosphere
Composition of Earth’s atmosphere Earth Has 4 main systems
that interact: The Atmosphere
Troposphere The layer of the atmosphere
closest to the earth.
There are 5 layers of the atmosphere seen to the right.
Exosphere
Atmosphere
Exosphere--
Thermosphere--
Mesosphere--
Stratosphere--
Troposphere--Contains most clouds and weather.Temperature cools as you go higher50% of sun’s energy passes through, 50% is reflected back.Most of the troposphere’s heat is from Earth (convection)
Troposphere and Clouds Among other gases there is water vapor in
the troposphere. Clouds—form when air rises, cools to its dew
point, and becomes saturated (moist).
Water Cycle Demo
Precipitation-falling water in the form of rain, freezing rain, sleet, snow, or hail
Section 2: Earth’s WeatherTroposphere Weather—the atmosphere’s condition in
terms of temperature, cloud cover, wind speed and direction, humidity, and air pressure.
What are different types of weather? ____________________________________________________________________________________________________________________________________________
Temperature—a measure of how fast air molecules are moving.
When molecules are moving rapidly, temperature is high.
Celsius and Fahrenheit thermometers measure air temperature.
Section 2: Earth’s WeatherTroposphere
What is the temperature like today? Hot/ Cold ______________________ Degrees Fahrenheit_______________ Degrees Celsius _________________
Section 2: Earth’s WeatherTroposphere
Energy is transferred between fast-moving molecules and slower-moving molecules.
Conduction—transfer of energy when molecules collide. Give an example of something heating up due to
conduction: __________________________________
Convection occurs when warm air rises and cool air sinks. Give an example of something heating up due to
convection: ___________________________________
Section 2: Earth’s WeatherTroposphere
Air pressure— air weight that varies over Earth’s surface.
Warmer air is less dense and exerts less pressure.
Cooler air is more dense and exerts more pressure.
Section 2: Earth’s WeatherTroposphere
Air Pressure Demonstration—Write about what you learned
Humidity— the amount of water vapor in the air
Temperature affects how much moisture is in the air.
Composition of Earth Earth Has 4 main systems that interact:
The Atmosphere The Hydrosphere
All of Earth’s water, whether in the atmosphere, glaciers, oceans, lakes or rivers.
The Biosphere The Geosphere
Composition of Earth Earth Has 4 main systems that interact:
Earth’s systems
Atmosphere Hydrosphere Biosphere Geosphere
water life land/rockAir/gases
The Hydrosphere – water Earth
Our Earth is mostly water
Approximately 70% of the Earth’s surface is water
30% of the Earth’s surface is land
Pie charts represent % of the whole
The Hydrosphere Water on Earth is a unique feature that clearly
distinguishes our "Blue Planet" from others in the solar system.
Not a drop of liquid water can be found anywhere else in the solar system. Earth has just the right mass, the right chemical composition, the right atmosphere, and is the right distance from the Sun that permits water to exist mainly as a liquid.
Water is the universal solvent and the basis of all life on our Planet.
Our Water Cycle Water, which covers the majority of the Earth’s
surface (the hydrosphere), circulates through the crust, oceans, and atmosphere in what is known as the water cycle.
Water Cycle—water is in constant motion The Sun provides water cycle’s energy Water on the surface absorbs heat and
evaporates, entering the atmosphere Condensation—water vapor changes back into
liquid. Clouds of water become heavy and water falls to
Earth as precipitation. The cycle repeats itself continuously.
The Water Cyclehttp://www.kidzone.ws/water/index.html
Run and get a glass of water and put it on the table next to you. Take a good long look at the water. Now -- can you guess how old it is?
The water in your glass may have fallen from the sky as rain just last week, but the water itself has been around pretty much as long as the earth has!
When the first fish swam in the ocean, your glass of water was part of that ocean. When the Brontosaurus walked through lakes feeding on plants, your glass of water was part of those lakes. When kings and princesses, knights and squires took a drink from their wells, your glass of water was part of those wells.
And you thought your parents were OLD
Evaporation: Evaporation is when the sun heats up water
in rivers or lakes or the ocean and turns it into vapor or steam. The water vapor or steam leaves the river, lake or ocean and goes into the air.
Do plants sweat?
Well, sort of.... people perspire (sweat) and plants transpire. Transpiration is the process by which plants lose water out of their leaves. Transpiration gives evaporation a bit of a hand in getting the water vapor back up into the air.
Condensation: Water vapor in the air gets cold
and changes back into liquid, forming clouds. This is called condensation.
You can see the same sort of thing at home... pour a glass of cold water on a hot day and watch what happens. Water forms on the outside of the glass. That water didn't somehow leak through the glass! It actually came from the air. Water vapor in the warm air, turns back into liquid when it touches the cold glass.
Precipitation: Precipitation occurs when so
much water has condensed that the air cannot hold it anymore. The clouds get heavy and water falls back to the earth in the form of rain, hail, sleet or snow.
Collection: When water falls back to earth
as precipitation, it may fall back in the oceans, lakes or rivers or it may end up on land. When it ends up on land, it will either soak into the earth and become part of the “ground water” that plants and animals use to drink or it may run over the soil and collect in the oceans, lakes or rivers where the cycle starts
Fill in the diagram in your notesThe earth has a limited
amount of water. That water keeps going around and around and around and around and (well, you get the idea) in what we call the "Water Cycle". This cycle is made up of a few main parts:
evaporation (and transpiration)
condensation precipitation collection
Accumulation - the process in which water pools in large bodies (like oceans, seas and lakes).Condensation - the process in which water vapor (a gas) in the air turns into liquid water. Condensing water forms clouds in the sky. Water drops that form on the outside of a glass of icy water are condensed water. (This term appears twice in the diagram.)Evaporation - the process in which liquid water becomes water vapor (a gas). Water vaporizes from the surfaces of oceans and lakes, from the surface of the land, and from melts in snow fields.Precipitation - the process in which water (in the form of rain, snow, sleet, or hail) falls from clouds in the sky.Subsurface Runoff - rain, snow melt, or other water that flows in underground streams, drains, or sewers.Surface Runoff - rain, snow melt, or other water that flows in surface streams, rivers, or canals.Transpiration - the process in which some water within plants evaporates into the atmosphere. Water is first absorbed by the plant's roots, then later exits by evaporating through pores in the plant.
How are the Hydrosphere and Atmosphere connected?
WATER CYCLE SONG
Bill Nye’s take on the water cycle… http://jp.youtube.com/watch?v=ZQIVx_BOCJU
http://jp.youtube.com/watch?feature=related&hl=en&v=2XU9_2zkQSE
http://jp.youtube.com/watch?v=dGSkcrw00HM&feature=related
Composition of Earth Earth Has 4 main systems that interact:
Earth’s systems
Atmosphere Hydrosphere Biosphere Geosphere
water life land/rockAir/gases
Composition of Earth Earth Has 4 main systems that interact:
The Atmosphere The Hydrosphere The Biosphere
Life on Earth Sea life, plants, flying creatures, humans Encompasses hydrosphere, upper geosphere, and
lower atmosphere. The Geosphere
BIOSPHERE
The relationship between an organism and its environment is the study of ecology.
Living things interact with Non living things in the Biosphere
Biotic Factors—living components in the biosphere
Biotic, meaning of or related to life, are living factors. Plants, animals, fungi, protist and bacteria are all biotic or living factors.
Living things interact with Non living things in the Biosphere
AbioticAbiotic Factors—nonliving components in the biosphere
Environmental factors such habitat (pond, lake, ocean, desert, mountain) or weather such as temperature, cloud cover, rain, snow, hurricanes, etc. are abiotic factors.
Role of Water in the Biosphere
Water is the universal solvent and the basis of all life on our Planet.
The hydrosphere is important to the Biosphere!
Role of the Sun for the biosphere
The Sun provides the light and heat necessary to maintain life on Earth and is the ultimate source of energy.
Biotic and abiotic factors combine to create a system or more precisely, an ecosystem.
An ecosystem is a community of living and nonliving things.
Examples of ecosystems A pond. Abiotic factors? Biotic Factors?
Ocean Ecosystem Abiotic? Biotic?
Grassland ecosystem
The Impact of Changing Factors
If a single factor is changed, perhaps by pollution or natural phenomenon, the whole system could be altered.
For example, humans can alter environments through farming or irrigating. While we usually cannot see what we are doing to various ecosystems, the impact is being felt all over.
For example, acid rain in certain regions has resulted in the decline of fish population.
A food chain Shows how each living thing gets its food. Some animals eat plants and some animals eat other
animals. For example, a simple food chain links the trees, the
giraffes and the lions. Each link in this chain is food for the next link. A food chain always starts with plant life and ends with an animal.
A food chain An is added and means “is eaten by”; also shows
the flow of energy (the giraffe gets his energy from the leaves)
Now we have made a simple food chain.
Biosphere Here is an
example of another food chain.
Plants are called producers or autotrophs because they are able to use light energy to make their own food.
Animals cannot make their own food so they must eat plants and/or other animals. They are called consumers or heterotrophs. There are three groups of consumers.
Herbivores are animals that only eat plants or plant products (seeds). They are also called primary consumers
Carnivores are animals that eat other animals.
There are 2 kinds of carnivores
Secondary Consumers are carnivores that eat herbivores
Herbivores are primary consumers
Something that makes its own food is called a producer
Tertiary consumers are carnivores that eat other carnivores
killer whales (tertiary consumer—they eat another carnivore)
Dolphin (secondary consumer—they eat a herbivore)
Herring (primary consumer—they only eat plants)
Photoplankton (this plant produces its own food)
Make your own food chain Find in your notes where it says to make your
own food chain. Start with a plant on the very left side. The arrow means “is eaten by” so think of the
next thing that might eat your plant…and so on.
Animals and people who eat BOTH animals and plants are called omnivores
WE EAT PLANTS WE EAT MEAT
To sum up:
Animals that eat only plants.
Animals that eat only animals.
Animals that eat both animals AND plants. Humans are also omnivores!
Then there are decomposers (bacteria, worms, and fungi) which feed on decaying matter.
These decomposers speed up the decaying process that releases mineral salts back into the food chain for absorption by plants as nutrients.
Games http://www.sheppardsoftware.com/content/animals/
kidscorner/foodchain/foodchain.htm producer consumer game (pic of cow)
http://www.sheppardsoftware.com/content/animals/kidscorner/foodchain/foodchain.htm
Omnivore, carnivore, herbivore game (pic of person,frog, lion and bear)
http://www.sheppardsoftware.com/content/animals/kidscorner/matching/mcarnivores.htm
Matching game (herbivore, carnivore, omnivore)
Do you know why there are more herbivores than carnivores?
In a food chain, energy is passed from one link to another
Lets say a plant has the # 100 to represent the energy it has made.
When a herbivore eats, it does not get all the plant’s energy. It uses up some of the energy in everyday activities. The herbivore may only get 10% of that energy.
A carnivore then eats this herbivore. The carnivore only gets 1% of that plants original energy. This is why the carnivore has to eat many herbivores to get enough energy to grow.
Energy and mass is transferred from one level of the food chain to the next with an efficiency of about 10%.
Because of the large amount of energy that is lost at each link, the amount of energy that is transferred gets lesser and lesser
The further along the food chain you go, the less food (and energy) remains available.
ENERGY’S MOVEMENT IN THE FOOD CHAIN
This energy pyramid shows many trees & shrubs providing food and energy to giraffes.
Note that as we go up, there are fewer giraffes than trees & shrubs and even fewer lions than giraffes
... as we go further along a food chain, there are fewer and fewer consumers.
In other words, a large mass of living things at the base is required to support a few at the top ... many herbivores are needed to support a few carnivores
Most food chains have no more than four or five links
There cannot be too many links in a single food chain because the animals at the end of the chain would not get enough food (and hence energy) to stay alive.
Most animals are part of more than one food chain and eat more than one kind of food in order to meet their food and energy requirements. These interconnected food chains form a food web.
FOOD CHAIN vs FOOD WEB
FOOD CHAIN
FOOD WEB
Note that the arrows are drawn from food source to food consumers ...
substitute the arrows with the words "eaten by"
The arrows also show the way energy is moving.
Recap The sun is the source of energy Water is the source of life on earth Water is in the hydrosphere, geosphere and
atmosphere, and biosphere. The living things in the biosphere are dependent on
many nonliving things. (abiotic and biotic) There are food chains and webs that show what
animals eat. The higher up on the food chain, the less predators they have.
Be able to describe who receives the most of the sun’s energy and how energy moves and is converted through the food chain.
Be able to describe how the systems are connected (atmosphere, hydrosphere, and biosphere)
http://www.ecokids.ca/pub/eco_info/topics/frogs/chain_reaction/index.cfm make a foodchain
http://www.sheppardsoftware.com/content/animals/kidscorner/games/foodchaingame.htm resource
http://www.sheppardsoftware.com/content/animals/kidscorner/games/foodchaingame.htm game food chain
Fun with foodwebs http://www.harcourtschool.com/activity/food/food_menu.html
Fill in foodwebs http://www.gould.edu.au/foodwebs/kids_web.htm
6th Sense Thursday February 12th
Q: Where do rocks come from?
Composition of Earth Earth Has 4 main systems that interact:
Earth’s systems
Atmosphere Hydrosphere Biosphere Geosphere
water life land/rockAir/gases
Composition of Earth Earth Has 4 main systems that interact:
The Atmosphere The Hydrosphere The Biosphere The Geosphere
The solid earth (rock) Continental earth, and solid earth (continental crust)
under water and the oceans (oceanic crust)
What are rocks made of?
Minerals are not made by people; they are …
…naturally occurring substances.
Name four properties (or clues) that scientists use to identify minerals.
Color, luster, streak, and hardness
Property of mineral: color The color of a rock can be a clue to what it
is made up of. Sometimes the color can help you figure out what it is, other times it can fool you.
Copper is reddish Sulfer is yellowish
Sometimes the color can help you figure out what it is, other times it can fool you. WHICH ONE IS GOLD? WHICH ONE IS PYRITE,
OR BETTER KNOWN AS FOOLS GOLD.
Did you guess? As you can see… Color may be misleading. GOLD FOOLS GOLD
Which property means the way the light bounces off the mineral?
What words can be used to describe a mineral’s luster?
Glassy, dull, shiny, greasy
Property of mineral: streak Streak is the color of the powdered mineral
Property of mineral: hardness How tightly the atoms are bonded together in
the rock…. How HARD or soft is the mineral?
What are three testers that can be used to determine a mineral’s hardness?fingernail, penny, nail
TYPES OF ROCKSClassified by how they
Are formed.
IGNEOUS ROCKS(melted rock from inside
The Earth cools)
SEDIMENTARY(sediment collects in
Layers that form rocks)
METAMORPHIC(rocks form from
Pressure and temp)
EXTRUSIVEMelted rock cools
Melted rock that reachesThe surface is called lava.
INTRUSIVEMagma forced up but Doesn’t reach surface
Magma—melted rock that Doesn’t reach the earth.
Igneous Rocks
Igneous RocksAny rock that forms from magma or
lava
MAGMA--
LAVA—reaches Earth’s surface
Never reaches Earth’s surface
Origin of Igneous
Classified according to where they are found.
Extrusive rock— formed from lava that erupted onto the Earth’s surface. Fine grained. (ex. Basalt)
Intrusive rock— formed when magma hardens beneath the Earth’s surface. Coarse grained. (ex. Granite)
EXTRUSIVE ROCKS (lava) Extrusive Rocks Form 2 ways
Volcanoes erupt and shoot out lava and ash. Large cracks in Earth’s crust (fissures), can open
up. Lava oozes out onto ground or into water.
Sedimentary Rocks
Sediments form RockSediments form RockForm from particles deposited by water
and wind.
Sediment—small, solid pieces of material that come from rocks or living things.
Water, wind, and ice can carry sediment and deposit it in layers.
Examples of Sediment Mud Pebbles Shells Bones Sand grains Leaves stems Living remainsOver time, any remains from living may slowly harden
and change into fossils trapped in the rock.
Sedimentary rocks form in 3 ways: Detrital Rocks
Made up of grains of minerals or other rocks.
The weight of the sediments squeezes them into layers.
Sedimentary rocks form in 3 ways: Organic rocks— formed from fossils (the hard
parts of dead organisms like bones/ shells
Sedimentary rocks form in 3 ways:
Chemical RocksSeawater filled with minerals evaporates. As water evaporates, layers of minerals are left behind.
Types of Sedimentary RockClastic (Detrital Rocks)Clastic (Detrital Rocks) Forms when rock fragments are squeezed
together. (ex. Sandstone)Organic RocksOrganic Rocks Forms where remains from plants/ animals
are deposited. (ex. Coal and limestone)Chemical RocksChemical Rocks Forms when minerals that are dissolved in a
solution crystallize.
The breaking down and wearing away of rocks is called…
The movement of sediments from one place to another is called…
Erosion Destructive forces break up and wear away
present rock. Heat, cold, rain, waves, grinding ice Running water or wind loosen and carry away
the fragments of rock.
Deposition The process by which sediment settles out of
the water or wind carrying it. The eroding water or wind slows and
deposits the sediment. If carried by water, rock fragments and other
materials sink to the bottom of a lake or ocean.
http://www.classzone.com/books/earth_science/terc/content/visualizations/es0604/es0604page01.cfm?chapter_no=visualization
Compaction
Its been moved away and now dropped. Heavy thick layers of sediment build up The weight presses down on the layers Compaction—process that presses
sediments together. Each year, new sediments fall creating new
layers. The layers are often visible
Cementation The process in which dissolved minerals
crystallize and glue particles of sediment together.
Where loose sediments become solid sedimentary rock Minerals dissolve in water and then seep into
spaces between sediment.
Review:Processes that change sediment into sedimentary rock
1. Erosion2. Deposition3. Compaction4. Cementation
http://www.classzone.com/books/earth_science/terc/content/investigations/es0602/flash/es0602_p02_rockcycle.swf
Metamorphic Rocks
Metamorphic Rocks Heat and pressure deep in the Earth can
change any rock into a metamorphic rock. Heat from mantle Pressure due to depth. Minerals can change into
other minerals.
Classifying Metamorphic Rocks Arranged by the grains that make up the rocks. Foliated—grains arranged in parallel layers/ bands
(slate, schist, gneiss) Nonfoliated—Mineral grains are arranged
randomly (marble and quartzite)
The Rock Cycle
Rock Cycle A series of processes on Earth’s surface and
inside the planet that slowly change rocks from one kind into another.
Earths constructive and destructive forces (and plate tectonics) move rocks through the rock cycle.
Quiz: http://www.learner.org/interactives/rockcycle/diagram2.html http://www.learner.org/interactives/rockcycle/diagram.html
http://www.cdli.ca/CITE/rocks_general.htm
Rock Cycle SongRock Cycle Song (Sing to the tune of "Row, Row, Row Your
Boat") SEDIMENTARY rock
Has been formed in layers Often found near water sources
With fossils from decayers
Then there's IGNEOUS rock Here since Earth was born
Molten Lava, cooled and hardened That's how it is formed
These two types of rocks Can also be transformed
With pressure, heat and chemicals METAMORPHIC they'll become.
Memorize this!!!
Bibliography http://www.emints.org/ethemes/resources/
S00000504.shtml http://www.emints.org/ethemes/resources/
S00000299.shtml http://serc.carleton.edu/NAGTWorkshops/
visualization/collections/erosion_deposition.html http://www-rohan.sdsu.edu/~rhmiller/
sedimentaryrocks/SedimentaryRocks.htm
REVIEW POINT Major Concepts Identify and describe the 4 major systems that
interact on Earth. Explain how water might be involved in all 4
systems. Explain how the Sun is important to life on
Earth
Plate TectonicsPlate Tectonics
The Geosphere – solid Earth The geosphere is in a constant state of
motion that gives rise to movement of the continents.
The unifying theory that explains how continental drift is possible is called plate tectonics, which was developed by geologists in the 1960s.
Earth has 4 layers Earth has four layers
Outermost layer is the crust. Solid layer that flows slowly like putty is the
mantle. Outer core— molten metal above the inner core. Inner core— dense iron core; very hot and dense.
Why/ How is the geosphere in constant motion?
Plate boundaries are edges where plates meet.
Tension can pull plates apart, resulting in new lithosphere forming in the gaps.
Colliding plates could cause mountains to form as rock crumbles and folds.
Subduction occurs when a denser plate sinks underneath a less dense plate.
Shearing causes faults and earthquakes as two plates slide past each other.
Plate movement theory—convection in the mantle circulates material and moves plates.
Ridge-push at mid-ocean ridges causes plates to slide down the slope.
Slab-pull happens as plates move away from mid-ocean ridges and become denser.
First, you have to understand what makes up the geosphere
The Earth’s Interior
The Science of GeologyThe Science of Geology
Geologists – scientists Geologists – scientists who study the forces that who study the forces that make and shape planet make and shape planet EarthEarth
Landforms – features Landforms – features formed in rock and soil by formed in rock and soil by water, wind and waveswater, wind and waves
Geology – the study of planet Earth
Studying surface changes1. Constructive forces – shape the
surface by building up mountains and landmasses.
Ex: land is made Destructive forces – slowly wear
away mountains and other land features.
Ex: land is destroyed
A Journey to the Center of the Earth –
Temperature – at a depth of about 20m the temperature gets warmer as you go deeper into the earth’s interior. For every 40 m, the temperature rises 1degree C, then it eventually increases more slowly.
Pressure – the deeper you go the greater the pressure (force pushing on a surface of area)
The Crust – layer of rock that forms the Earth’s outer skin. Includes soil, water, mountains, etc. It is the thinnest layer – thinner beneath the oceans than beneath the continents (5 – 40 km thick)
Oceanic Crust – the crust beneath the oceans. Consists mostly of basalt rock.
Continental crust – the crust beneath the continents. Consists mostly of granite rock.
Second layer, nearly 3000 km thick. Top part made of rigid rock similar to the crust, lower part made of softer rocks.
Lithosphere – the crust and the upper rigid part of the mantle
Asthenosphere – lower part of the mantle made of soft rocks that can flow like a liquid (have plasticity)
The CoreConsists of two parts
Outer core – made of molten metal. (2250 km thick)
Inner core – a dense ball of solid rock. (1200 km thick). The pressure is so great that the iron and nickel cannot spread out and become liquid.
Convection Currents and the Mantle
Methods of Heat TransferRadiation transfer of thermal energy (heat)
in the form of waves. Does not require a medium. Ex: feeling warmth from a fire.
Methods of Heat Transfer
Conduction – heat transfer by direct contact.
Ex: Handle of a spoon in hot soup also becomes heated.
Methods of Heat Transfer Convection – heat
transfer by currents moving through a heated fluid (liquid or gas).
Ex: Warm air rises and cool air sinks in a room.
http://www.solarviews.com/eng/edu/convect.htm
Convection in the Earth’s Mantle The (lower mantle) is heated by the outer core,
the heated rocks become less dense and rise, while the cooler rocks from above sink. The repeated process results in continuous cycles of material.
Drifting Continents
Chapter 9, Section 3Pages 326 – 330
Continental Drift – theory that the continents had once been
joined together in a single landmass and have since drifted apart.
Theory first proposed by Alfred Wegener Pangaea – the one supercontinent believed to
have existed 300 million years ago
Evidence for Continental Drift
Alfred Wegener (1880-1930), a German meteorologist and geologist, was the first person to propose the theory of continental drift.
200 mya the continents were originally joined together, forming Pangaea, meaning "All-earth".
Evidence for Continental Drift
Evidence from landforms Mountain range – in Africa
matched a mountain range in South America
European coal fields match coal fields in North America
Evidence for Continental DriftEvidence from Fossils
Fossil – trace of an organism that has been preserved in rock
Mesosaurus – reptile whose fossils were found in S. America and Africa. This organism could not have swum long distances in salt water,
Evidence for Continental DriftEvidence from fossils (continued)
Lystrosaurus – reptile whose fossils were found in Africa and India. This organism could not have swum across the ocean.
Glossopteris – a seed fern plant. Identical fossils were found in S. America, Africa, Antarctica, India and Australia. /seeds could not have traveled by air or water across vast oceans.
Evidence for Continental Drift
Evidence from climate Spitsbergen island – located in
the Arctic Ocean, north of Norway. Fossils of tropical plants have been found there.
Evidence that continental glaciers once covered S. Africa
Scientists Reject
Hypothesis
Wegener could not provide a satisfactory explanation for the force that pushes or pulls continents
geologists rejected the theory (until new evidence was discovered later.)
Sea-Floor Spreading
Mid-ocean ridge – longest chain of mountains in the world
Where volcanic and earthquake activities occur
Rift Valley – runs lengthwise through the mid-ocean ridge
The Theory of Sea-Floor Spreading
Harry Hess in 1960 The ocean floors move like conveyer
belts, carrying the continents with them. Since the continents are attached to the
ocean floor, sea-floor spreading could be the force causing the continents to move.
The theory of sea floor spreading
At mid-ocean ridges molten material rises from the mantle and erupts.
The molten material then spreads out, pushing older rock to both sides of the ridge.
Evidence from Molten Material – scientists discovered “pillow lava” forming along the mid-ocean ridge. These rocks form when molten material hardens quickly after erupting under water.
Evidence from Magnetic Stripes – patterns of magnetic stripes match on either side of the mid-ocean ridge, suggesting that the ocean floor is spreading evenly in opposite directions.
Evidence (continued) Evidence From Drilling Samples – The
Glomar Challenger, a drilling ship, drilled holes in the ocean floor. Discovered that rocks along mid-ocean ridges are much younger than rocks farther away.
Subduction at Deep—Ocean Trenches
Subduction – process whereby the ocean floor plunges into the mantle and melts at deep underwater canyons called deep-ocean trenches.
Subduction at Deep—Ocean Trenches
Subduction and Sea-Floor Spreading work together like a conveyor belt, moving the continents.
Subduction at Deep—Ocean Trenches (cont.)
Subduction and the Earth’s Oceans Subduction in the Pacific Ocean – the deep
trenches surrounding the Pacific Ocean result in more subduction that sea-floor spreading. The result is that the Pacific Ocean floor is getting smaller.
Subduction in the Atlantic Ocean – the Atlantic Ocean floor is becoming
TYPES OF PLATE MOVEMENT
Divergence, Convergence, and Transform At the boundaries of the plates, various
deformations occur as the plates interact; they separate from one another (seafloor
spreading), collide (forming mountain ranges), slip past one another (subduction zones, in which
plates undergo destruction and remelting), and slip laterally.
Divergent Plate Movement Seafloor spreading is the
movement of two oceanic plates away from each other,
results in the formation of new oceanic crust (from magma that comes from within the Earth's mantle)
Happens along a a mid-ocean ridge.
Where the oceanic plates are moving away from each other is called a zone of divergence.
Convergent Plate Movement: When two plates collide, some
crust is destroyed in the impact and the plates become smaller. The results differ, depending upon what types of plates are involved. Oceanic Plate and Continental Plate - When a thin, dense oceanic plate collides with a relatively light, thick continental plate, the oceanic plate is forced under the continental plate; this phenomenon is called subduction. Two Oceanic Plates - When two oceanic plates collide, one may be pushed under the other and magma from the mantle rises, forming volcanoes in the vicinity. Two Continental Plates - When two continental plates collide, mountain ranges are created as the colliding crust is compressed and pushed upwards.
Lateral Slipping Plate Movement When two plates move
sideways against each other, there is a tremendous amount of friction which makes the movement jerky.
The plates slip, then stick as the friction and pressure build up to incredible levels.
When the pressure is released suddenly, and the plates suddenly jerk apart, this is an earthquake.
