Earth's Surface and Geological Features
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Questions and Answers

Which type of seismic wave is also known as a compressional wave?

  • Love wave
  • R wave
  • S wave
  • P wave (correct)
  • During which geologic era do we currently live?

  • Precambrian
  • Paleozoic
  • Mesozoic
  • Cenozoic (correct)
  • Which feature represents the edge of the continental crust?

  • Oceanic trench
  • Continental slope (correct)
  • Continental shelf
  • Mid-oceanic ridge
  • What is the primary cause of earthquakes?

    <p>Movement of rock along faults</p> Signup and view all the answers

    What do we call the point on the Earth's surface that is directly above the focus of an earthquake?

    <p>Epicenter</p> Signup and view all the answers

    What percentage of the Earth's surface is occupied by oceans?

    <p>71%</p> Signup and view all the answers

    What are mountain roots?

    <p>Deep, stable portions of the Earth's crust supporting mountain ranges</p> Signup and view all the answers

    What is the primary concept explained by the elastic rebound theory?

    <p>The storage and release of energy in fault lines</p> Signup and view all the answers

    What is formed when divergent boundaries occur?

    <p>Rift valleys</p> Signup and view all the answers

    Which process transforms existing rocks into metamorphic rocks?

    <p>Metamorphism</p> Signup and view all the answers

    What type of rock is characterized by high silica content?

    <p>Felsic rocks</p> Signup and view all the answers

    What occurs at convergent boundaries?

    <p>Plates slide towards each other</p> Signup and view all the answers

    Which is NOT a feature associated with convergent boundaries?

    <p>Rift valleys</p> Signup and view all the answers

    How many major lithospheric plates does the Earth's lithosphere have?

    <p>Six</p> Signup and view all the answers

    What is the main component of rocks?

    <p>Minerals</p> Signup and view all the answers

    Who proposed the theory of continental drift?

    <p>Alfred Wegener</p> Signup and view all the answers

    Which feature differentiates oceanic crust from continental crust?

    <p>Oceanic crust is denser and thicker than continental crust.</p> Signup and view all the answers

    What type of rock is formed from the solidification of molten magma or lava?

    <p>Igneous rocks</p> Signup and view all the answers

    What is the primary composition of the outer core of the Earth?

    <p>Iron and nickel</p> Signup and view all the answers

    How does the lithosphere move in relation to the asthenosphere?

    <p>The lithosphere moves on top of the semi-fluid asthenosphere.</p> Signup and view all the answers

    What characteristic allows the asthenosphere to facilitate tectonic plate movement?

    <p>It is partially molten, allowing flow.</p> Signup and view all the answers

    What occurs at the boundaries of tectonic plates?

    <p>Earthquakes and volcanic activity.</p> Signup and view all the answers

    Which type of igneous rock forms from magma that crystallizes slowly beneath the Earth's surface?

    <p>Intrusive</p> Signup and view all the answers

    What is the role of the inner core in relation to the Earth's structure?

    <p>It is a solid sphere under immense pressure.</p> Signup and view all the answers

    Study Notes

    Earth’s Surface Composition

    • 29% of Earth’s surface is land and 71% is ocean.
    • Continental shelf area increases the land area to 35% and decreases the ocean basin area to 65%.

    Oceanic Relief Features

    • Mid-oceanic ridge with a central rift where crust is pulled apart.
    • Continental shelves accumulate thick deposits of continental sediments.
    • Continental slopes are the edge of the continental crust.
    • Oceanic trenches are where oceanic crust slides beneath continental crust.

    Continents

    • Divided into active mountain-making belts and inactive regions of old, stable rock.
    • Continental shields and mountain roots are two types of stable structures.
    • Mountain Roots are the deep, stable portions of the Earth's crust that support mountain ranges.

    Time Scale

    • Time older than 570 million years (MY) is Precambrian time.
    • Three eras of time follow: Paleozoic, Mesozoic, and Cenozoic.
    • Geologic eras are subdivided into periods.
    • We live in the Holocene period (the last 12,000 years).

    Earthquakes

    • Shaking and trembling caused by rock movement beneath Earth's surface.
    • Most severe earthquakes occur near plate collision boundaries.
    • Earthquakes are the sudden release of stored energy.
    • Result of fast movement between two blocks of rock.
    • Released energy radiates away from the earthquake.
    • Main cause of earthquakes is faults on the Earth's crust.
    • A fault is a break between two blocks of rocks.

    Earthquake Terminology

    • The origin of the earthquake (where the fault begins) is the focus or hypocenter.
    • The point on the Earth's surface directly above the focus is the epicenter.

    Elastic Rebound Theory

    • Explains how energy is stored in deformed rocks along fault lines and released during an earthquake.
    • Seismic waves are vibrations that travel through Earth carrying energy released during an earthquake.

    Seismic Waves

    • Two types of waves produced during an earthquake.
    • Body waves: travel through Earth’s interior.
      • P wave (primary): compressional wave that causes alternate compression and expansion of the rock.
    • Surface waves: travel along the Earth’s surface.

    Metamorphic Rocks

    • Created when existing rocks are transformed by heat, pressure, or chemically active fluids.
    • This process, known as metamorphism, changes the mineral composition and structure.

    Earth's Composition

    • 91 elements occur naturally in the Earth’s crust.
    • Eight elements make up more than 98 percent of the earth’s crust.
    • A mineral is a naturally occurring, inorganic solid with a characteristic chemical composition and a crystalline structure.
    • Felsic rocks (comprising the crust) are high in silica content.
    • **Ultramafic rocks **(comprising the mantle) are high in magnesium and iron content.

    Plate Tectonics

    • The theory proposed by Alfred Wegner in 1912 suggests that the crustal plates are moving over the mantle.
    • Wegner proposed that today’s continents once formed a single landmass, called Pangaea.
    • The uppermost mantle and the overlying crust behave as a strong, rigid layer, known as the lithosphere, which is broken into segments called plates.

    Lithospheric Plates

    • The Earth’s lithospheric shell is divided into six great lithospheric plates and at least nine lesser plates.
    • Divergent boundaries (Constructive): two plates slide apart from each other. They are characterized by:
      • Rift valleys
      • Tilted block mountains
    • Convergent boundaries (Destructive): two plates slide towards each other, forming either a subduction zone or a continental collision. They are characterized by:
      • Trenches
      • Mountain ranges
      • Island arcs
      • Volcanic arcs
    • Transform boundaries (Conservative): plates slide past each other along transform faults.

    Earth Structure and Composition

    • The layers of the Earth’s interior include the crust, mantle, liquid outer core, and solid inner core.
    • Crust: outermost layer, thinnest and solid, composed of continental and oceanic crust.
    • Mantle: thick layer beneath the crust, semi-solid rock that flows slowly.
    • Outer Core: Liquid layer beneath the mantle, composed mainly of iron and nickel.
    • Inner Core: innermost layer, solid sphere due to high pressure, primarily iron and nickel.

    Lithosphere and Asthenosphere

    • Lithosphere: rigid outer layer of Earth (crust + upper mantle).
    • Asthenosphere: semi-fluid layer of the upper mantle beneath the lithosphere.

    Rocks

    • Rocks are aggregates of mineral particles.
    • Igneous Rocks: formed from the solidification of molten magma or lava.
      • Intrusive (Plutonic): crystallize slowly beneath the Earth's surface.
      • Extrusive (Volcanic): erupt and cool quickly on the surface.
    • Sedimentary Rocks: formed from the accumulation and compaction of sediments.

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    ENV 241 Lithosphere Notes PDF

    Description

    Explore the composition of Earth's surface and the various geological features found within our oceans and continents. This quiz covers land-to-ocean ratios, oceanic relief features, and the geological timescale, including major eras and periods. Test your knowledge about the Earth's structure and its history!

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