chapter 2 the earth. section i. planet earth what do you know about the solar system?
TRANSCRIPT
Chapter 2The Earth
Section I. Planet Earth What do you know about the Solar
System?
A. Our Solar System The sun is at the center of our Solar
System Sun creates a strong pull of gravity Keeps objects such as Earth revolving
around the Sun
Our Solar System Revolution – in astronomy, the Earth’s
yearly trip around the sun 365 ¼ days Why is the ( ¼ ) important to know??
Rotation – the Earths daily trip turning on its axis How long is a day?
In history…. People believed that the solar system
revolved around Earth Geocentrism Connected to religion
But it was Galileo (16th century) that actually fought for the now accepted theory that we were the ones moving Heliocentrism
What’s the idea behind the theories? Why would people think we were
geocentric?? Which theory would you side with if you
had to choose? What would happen without the sun?
The “Classical” Planets: Neighbors in Space Before it was believed we had nine
planets now we just classify eight Inner Planets (Terrestrial)
Mercury Venus Earth (only one with sustainable life) Mars
The “Classical” Planets: Neighbors in Space Outer Planets (Gas Giants)
Jupiter Saturn Uranus Neptune
All have moons except Mars & Venus There are also asteroids, comets and
meteoroids
Pluto……..planet?? Discovery Channel, August 24th, 2006 [Much-maligned Pluto doesn't make the
grade under the new rules for a planet: "a celestial body that is in orbit around the sun, has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a ... nearly round shape, and has cleared the neighborhood around its orbit.“]
[Pluto is automatically disqualified because its oblong orbit overlaps with Neptune's.]
B. Getting to know the Earth The earth is divided into categories
Hydrosphere – part of Earth made up of oceans, lakes, rivers, and other bodies of water
Lithosphere – part of Earth made up of continents and islands
Atmosphere – a layer of gases that surrounds the Earth
Biosphere – the part of the Earth that supports life
Hydrosphere = WATER Earth is 70% water
Lithosphere = Land Earth is 30% land
Atmosphere = Air Above earth’s surface you have a layer
of gases 78% nitrogen, 21% oxygen and the rest
argon and other gases Our natural vegetation is essential to the
recyclement of our oxygen
Biosphere = life The part of earth that supports life Life outside of the biosphere only exist
with mechanical life support system Space shuttle
Air + Land + Water =Biosphere! Bio=life! Hence, Biology….
C. Landforms Natural features of the earth’s surface
that vary in shape and elevation 4 major landforms-
Mountains Hills Plateaus PlainsAlso have valleys, canyons, and basins
All contain rivers, lakes and streams
Underground Landforms Landforms underwater are as diverse as
those found on dry land Range from flat plains to mountain
ranges, cliffs, valleys and deep trenches
Earth’s most visible landforms From space the most visible landforms are
the 7 continents Australia Antarctica Europe Asia North America South America Africa
**** Locate continents on your map ****
Continental Shelf Part of a continent that extends
underwater
Long narrow underground canyon (Pacific Ocean)
Section II. Forces of Change How does earth change? What processes are responsible for such
changes?
Forces of Change On the surface
Wind, water, etc Originate from the interior
Volcanic eruptions, earthquakes, etc
Earth’s Structure The earth is composed of three layers
Core Inner core is made up of iron and nickel
under enormous pressure Outer layer is liquid made up of melted
iron and nickel
Mantle Thick layer of hot dense rock Mixture of elements that continually
rises, cools, sinks, warms up and rises again
Responsible of 80% of heat generated from earth’s interior
Crust Broken up into more than a dozen great
slabs of rock called plates that rest (float) on a partially melted layer in the upper mantle
Carry the earth’s oceans and continents
Continental Drift TheoryPangaea Theory that all the continents were once
joined and slowly started to drift apart
Plate theory“Continental Drift” Pangaea – a gigantic supercontinent
that eventually broke apart (drifted) into smaller continents due to plate movement
Crust=Plates
Plate Tectonics Plates are continually moving At times they may crash, pull apart, grind
or slide past each other Constantly changing the face of the planet They push up mountains, create
volcanoes, and produce earthquakes Theory: heat rising from the core create
slow-moving currents within the mantle which then shift the plates around
Crust=Plates
Internal forces of change1. Colliding2. Subduction3. Accretion4. Spreading5. Folds6. Faults7. Earthquakes8. Volcanic Eruptions
1. Colliding Giant continental plate collide
Creates mountains Himalayas
2. Subduction A heavier sea plate dives beneath the
lighter continental plate Plunging into the earth’s interior, the
sea plate becomes molten material Then as magma it bursts through the
crust to form volcanic mountains Andes
3. Accretion Pieces of earth’s crust come together
slowly as the sea plate slides under the continental plate
Creates underwater mountains with steep sides and sharp peaks
Creates new land often island chain at the boundary
4. Spreading Sea plates pull apart Deep cracks (rift) allow magma from
within the earth to well up between the plates
Magma hardens to build undersea volcanic mountains or ridges
Spreading keeps Europe and N. Ame apart
5. Folds (bends) Moving plates squeeze the earth’s
surface until it buckles or creates folds in layers of rock
6. Faults Plates grind or slide past each other
creating cracks in earth’s crust When land can no longer be folded the
earth’s crust cracks and breaks into huge blocks
Small tremors occur San Andres Fault in CA
7. Earthquakes Sudden, violent movements of plates along a
fault line Dramatically change the surface of the land and
the floor of the ocean Happen when different plates meet each other.
Tension builds up as the plates stick. The strain becomes so intense that the rocks suddenly snap and shift. This releases stored up energy along the fault. Eventually the ground trembles as sends shock waves which are felt
Ring of Fire Earthquake and volcano zone
surrounding the Pacific Ocean Boundary where the plates that cradle
the Pacific meet the plates that hold the continents surrounding the ocean
8. Volcanoes Volcanoes are mountains formed by lava or
magma that breaks through the earth’s crust
Often rise along plate boundaries where one plate plunges beneath another
In such a process the rocky plate melts as it dives downward into the hot mantle. Pressure builds, a funnel is created and hot magma rushes to the surface. The lava will eventually create a volcano
Volcanoes As a moving plate passes over these hot
spots, molten rock flowing out of the earth’s surface may create volcanic island chains
Hawaiian Islands Molten rock may also heat underground
water causing hot springs or geysers Yellowstone
External Forces of Change Wind and water change the earth’s surface (two
processes) Weathering – process that breaks down rocks on
the earth’s surface into smaller pieces Erosion – wearing away of the earth’s surface by
wind, glaciers, and moving water1. Weathering2. Wind Erosion3. Glacial Erosion 4. Water Erosion
Weathering Either physical weathering or chemical
weathering Physical – when large masses of rock are
physically broken down into smaller pieces Water seeps into the cracks in a rock and freezes,
then expands and causes the rock to split Chemical – changes in the chemical makeup of
rocks (transforming their minerals or combining them) Water mixed with carbon dioxide from the air easily
dissolves certain rocks such as limestone
Wind Erosion Movement of dust, sand, and soil from
one place to another Can be devastating or beneficial
Dust Bowl China Yellow River basin is thickly
covered with loess (fertile yellow-gray soil deposited by wind)
Glacial Erosion Glaciers – large bodies of ice that slowly
move across the earth’s surface Glacial movements change the landscape by
destroying forests, carving our valleys, etc However, when glaciers melt and recede
they leave behind large pules of rocks and debris (moraines)
Moraines can form long ridges of land or create glacial lakes
Water Erosion Most significant cause of erosion Fast moving water – rain, rivers,
streams, and oceans – cuts into the land wearing away the soil and rock
The resulting sediment (small particles of soil, sand and gravel) act like sandpaper and cut away at land
Grand Canyon
Section 3 – Earth’s water Hydrosphere!! Almost all of the hydrosphere is salt
water found in the oceans, seas and seawater lakes
The remainder is freshwater found in lakes, rivers, and springs
Water Cycle Regular movement of water through
1. Evaporation – sun, changing liquid into vapor or gas
2. Condensation – excess water vapor changes into liquid form
1. Forms clouds
3. Precipitation – rain, snow, or sleet that sinks into the grounds and soon is evaporated again
Bodies of Salt Water (97%) Oceans
1. Pacific2. Atlantic3. Artic4. Southern 5. Indian
Seas, Gulfs, and Bays Desalination – conversion saltwater into
freshwater
Freshwater (3%) Lakes, Streams, and Rivers Groundwater – freshwater that lies beneath
the earth’s surface Comes from rain and melted snow that filter
through the soil and from water that seeps into the ground from lakes and rivers
Can use wells to tap into freshwater Aquifer – underground porous rock layer
saturated with water in the form of streams