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The Geosphere

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    The Geosphere The Geosphere Presentation Transcript

    • THE GEOSPHERE Chapter 3, Section 1
    • Learning Objectives
      • Describe the composition and structure of the Earth.
      • Describe the Earth’s tectonic plates.
      • Explain the main cause of earthquakes and describe their effects.
      • Identify the relationship between volcanic eruptions and climate change.
      • Describe how wind and water alter the Earth’s surface.
    • The Structure and Composition of the Earth
    • The Earth as a System
      • The Earth consists of rock, air, water, and living things that all interact with each other.
      • There are four parts of the Earth
        • Geosphere (rock)
        • Atmosphere (air)
        • Hydrosphere (water)
        • Biosphere (living things)
    •  
    • Discovering Earth’s Interior
      • Scientists can study the interior of the Earth by using seismic waves.
      • Seismic waves are the waves that travel through Earth’s interior during an earthquake.
      • A seismic wave is altered by the nature of the material through which it travels.
      • Seismologists measure changes in the speed and direction of seismic waves that penetrate the interior of the planet.
      • This has helped seismologists to learn that Earth is made up of different layers and different substances.
    • The composition of the Earth
      • The Earth is made of three layers that are made of denser materials toward the center of the Earth.
      • The layers are determined by the chemical composition.
      • 3 Layers:
        • Crust
        • Mantle
        • Core
    •  
    • Crust
      • Thin outer layer
      • Light elements
      • Oceanic Crust:
        • 5 km to 8 km thick beneath ocean
        • Oldest is 200 million years old
      • Continental Crust:
        • 20 km to 70 km thick beneath continents
        • Average age is 2 billion years old
        • Oldest is 3.7 to 4.3 billion years old
    • Mantle
      • 64% of the mass of the Earth
      • 2,900 km thick
      • 500ºC to 900ºC (upper portion of mantle)
      • 4,000ºC (near the core)
      • Melting mantle produces the crust
    • Core
      • Radius = 3,400 km
      • Mostly iron but also contains some nickel.
      • Temperature is probably around 5,000ºC
    • The Structure of the Earth
      • The Earth can also be divided into layers based on physical properties.
      • 5 Layers:
        • Lithosphere
        • Asthenosphere
        • Mesosphere
        • Outer Core
        • Inner Core
    •  
    • Lithosphere
      • Most outer layer
      • Cool and rigid
      • 15 km to 300 km thick
      • Includes the crust and uppermost part of mantle
      • Divided into huge pieces called tectonic plates
    • Asthenosphere
      • Beneath the lithosphere
      • Plastic, solid layer of the mantle made of rock that flows slowly. This allows the tectonic plates to move.
      • 250 km thick
    • Mesosphere
      • Beneath the asthenosphere
      • 2,550 km thick
      • Name means the “middle sphere”
    • Outer Core
      • Beneath the mesosphere
      • 2,200 km thick
      • Made of liquid nickel and iron
    • Inner Core
      • The innermost layer of the Earth
      • 1,228 km radius
      • A sphere of solid nickel and iron at the center of the Earth.
    • Plate Tectonics
      • The lithosphere is divided into pieces called tectonic plates.
      • These plates glide across the asthenosphere like ice floats across a pond.
      • The continents are located on tectonic plates and move around with them.
      • The major tectonic plates include:
        • Pacific
        • North American
        • South American
        • African
        • Eurasian
        • Antarctic
    • Plate Tectonics
    •  
    • Plate Boundaries
      • Much of the geologic activity at the surface of the Earth takes place at the boundaries between tectonic plates.
      • Plates can:
        • Move away from one another
        • Collide with one another
        • Slip past one another
      • Enormous forces are generated at tectonic plate boundaries where the crust is pulled apart, squeezed together or is constantly slipping.
    • Mountain Building
      • When tectonic plates collide, slip by one another, or pull apart, enormous forces causes rock to break and buckle.
      • Where plates collide, the crust becomes thicker and pushed up and eventually forms a mountain range.
    • Earthquakes
    • Earthquakes
      • A fault is a break in the Earth’s crust.
      • Blocks of the crust slide past each other along fault lines.
      • When rocks that are under stress suddenly break, a series of ground vibrations is set off.
      • These vibrations are known as earthquakes.
      • Earthquakes are occurring all the time.
    • The Richter Scale
      • Used by scientists to quantify the amount of energy released by an earthquake.
      • Magnitude - The measure of the energy released by an earthquake.
      • The scale goes from 1.0 to 10.0.
      • Each increase of magnitude by one whole number is ten times greater and releases 31.7 times more energy than the whole number below it.
    • Richter Magnitudes Description Earthquake Effects Frequency of Occurrence Less than 2.0 Micro Microearthquakes, not felt. About 8,000 per day 2.0-2.9 Minor Generally not felt, but recorded. About 1,000 per day 3.0-3.9 Often felt, but rarely causes damage. 49,000 per year (est.) 4.0-4.9 Light Noticeable shaking of indoor items, rattling noises. Significant damage unlikely. 6,200 per year (est.) 5.0-5.9 Moderate Major damage to poorly constructed buildings over small regions. Slight damage to well-designed buildings. 800 per year 6.0-6.9 Strong Can be destructive in areas up to about 160 kilometres (100 mi) across in populated areas. 120 per year 7.0-7.9 Major Can cause serious damage over larger areas. 18 per year 8.0-8.9 Great Can cause serious damage in areas several hundred miles across. 1 per year 9.0-9.9 Devastating in areas several thousand miles across. 1 per 20 years 10.0+ Epic Never recorded Extremely rare (Unknown)
    •  
    • Volcanoes
    • Volcanoes
      • A volcano is a mountain built from magma.
      • Magma – melted rock that found beneath the surface of the earth
      • Located near tectonic plate boundaries where plates are sliding or separating from one another.
      • May occur on the land or under sea.
      • Under sea volcanoes may eventually break through the surface as islands.
    •  
    •  
    • Volcano Eruptions
      • A volcano erupts when the pressure of the magma inside becomes so great that it blows open the solid surface of the volcano.
      • Some volcanoes have magma flowing out of them all the time so the pressure never builds up and they never erupt.
      • Sometime before May 18, 1980
      Mt. St. Helens (Washington) Before…
      • May 18, 1980
      Mt. St. Helens, During…
      • May 18, 1980
      Mt. St. Helens, During…
    • Mt. St. Helens, During…
      • Mt. St. Helens, During…
      • May 19, 1982
      Mt. St. Helens, 2 Years after…
      • Large trees (some over 100 feet tall) flattened by the lateral blast from Mt. St. Helens.
      The Lateral Blast
    • An Approaching Ash Cloud
    • The Ash Fallout from Mt. St. Helens
    • Cleaning Up the Ash
    • The Before and After
      • Before
      • After
    • The Mudflow
    • Mt. St. Helens Today
    • Local Effects of Volcano Eruptions
      • Volcanic eruptions can be devastating to local economies and can cause great human loss.
      • Clouds of hot ash, dust, and gases can flow down the slope of a volcano at speeds up to 200 km/hour and sear everything in their path.
      • Volcanic ash can mix with water and produce a mudflow.
      • Ash that falls to the ground can cause buildings to collapse, bury crops, damage engines, and cause breathing problems.
    • Global Effects of Volcanic Eruptions
      • Can change Earth’s climate for several years.
      • Clouds of volcanic ash and sulfur-rich gases can reach the upper atmosphere.
      • Ash and gas spread across the planet and reduce the amount of sunlight that reaches the Earth’s surface.
      • Reduced sunlight can result in a decrease in the average global temperature over a period of several years.
    • Erosion
    • Erosion
      • The Earth’s surface is continually battered by wind and running water.
      • This moves rocks around and changes their appearance.
      • Erosion – the removal and transport of surface material.
      • Erosion wears down rocks and makes them smoother.
    • Water Erosion
      • Ocean waves erode coastlines.
      • Rivers can carve deep gorges into the Earth.
    • Water Erosion
    • Wind Erosion
      • Plant roots hold soil in place. Without plants the wind can blow soil away very quickly.
      • Soft rock can be carved away over time.
    • Wind Erosion