Geology Course - Earth's Layers
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Questions and Answers

What term is used for the processes that cause mineral or organic particles to settle and accumulate?

  • Weathering
  • Erosion
  • Sedimentation (correct)
  • Metamorphism

    • Which of the following is a type of sedimentary rock?

  • Basalt
  • Gneiss
  • Limestone (correct)
  • Granite

    • What is the main source of scientific knowledge about the Earth's history?

  • Sedimentary rock strata (correct)
  • Igneous rock strata
  • Metamorphic rock formations
  • Fossilized remains

    • Which agent of denudation is primarily responsible for the transport of sediments by wind?

    <p>Atmospheric movement</p> Signup and view all the answers

    What percentage of the Earth's crust is estimated to be made up of sedimentary rocks?

    <p>8%</p> Signup and view all the answers

    Which scientific discipline focuses specifically on the properties and origin of sedimentary rocks?

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

    What type of stress occurs when rock or sediment is buried?

    <p>Confining stress</p> Signup and view all the answers

    What is the term for the layered structure formed by the deposition of sedimentary rocks?

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

    What is the primary reason seismologists prefer moment magnitude over Richter magnitude?

    <p>It provides a more accurate measure of total energy released.</p> Signup and view all the answers

    How is the largest possible earthquake determined?

    <p>By the strength of the rocks involved.</p> Signup and view all the answers

    What method do geologists use to calculate the distance between an earthquake epicenter and a seismograph?

    <p>Time-travel curve.</p> Signup and view all the answers

    What does the arrival time of seismic waves at a recording station indicate?

    <p>The distance from the epicenter.</p> Signup and view all the answers

    What happens when a seismograph is located far from the earthquake epicenter?

    <p>Surface waves arrive even later than S-waves.</p> Signup and view all the answers

    What does the term 'slip' refer to in the context of an earthquake?

    <p>The amount of movement along a fault.</p> Signup and view all the answers

    Why do different seismic waves arrive at different times at a seismograph?

    <p>Due to varying wave speeds.</p> Signup and view all the answers

    To pinpoint the exact location of an earthquake, how many recording stations do geologists typically compare?

    <p>Three or more</p> Signup and view all the answers

    What is the primary characteristic that allows P-waves to travel through various materials?

    <p>P-waves compress and expand the material they move through.</p> Signup and view all the answers

    Why do P-waves travel faster in the mantle than in the Earth's crust?

    <p>Rock density increases with depth in the Earth.</p> Signup and view all the answers

    What type of motion does a Rayleigh wave exhibit during an earthquake?

    <p>An up-and-down rolling motion like an ocean wave.</p> Signup and view all the answers

    Which wave type is specifically unable to travel through liquids?

    <p>S-waves</p> Signup and view all the answers

    How does a seismograph work during an earthquake?

    <p>The weight causes the paper to move while the pen remains stationary.</p> Signup and view all the answers

    What is the term for the record of Earth vibration produced by a seismograph?

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

    What distinguishes S-waves from P-waves in terms of motion?

    <p>S-waves move particles at right angles to the wave direction.</p> Signup and view all the answers

    What characterizes Love waves during an earthquake?

    <p>They produce a side-to-side vibration.</p> Signup and view all the answers

    What is the primary purpose of drawing circles for each seismic station recording an earthquake?

    <p>To identify the epicenter of the quake</p> Signup and view all the answers

    What effect does sandy sediment have on structures during an earthquake?

    <p>It causes displacement and tilting</p> Signup and view all the answers

    What is the significance of the time-travel curve in seismology?

    <p>It links P and S wave arrivals to distance</p> Signup and view all the answers

    How do engineers prevent structural failure in areas with sandy soil during an earthquake?

    <p>By driving steel or concrete pilings to bedrock</p> Signup and view all the answers

    What is the phenomenon called when water-saturated soil loses its shear strength during an earthquake?

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

    Which of the following factors does NOT contribute to earthquake damage in structures built on soil?

    <p>Distance from the epicenter</p> Signup and view all the answers

    In which material can structures be safest from earthquake shaking?

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

    What happens to the pore water in saturated soil during the sudden shock of an earthquake?

    <p>Its pressure rises, affecting soil stability</p> Signup and view all the answers

    What is the primary purpose of borehole geophysics?

    <p>To record physical, chemical, and electrical properties of rock/fluid mixtures</p> Signup and view all the answers

    What does a well log primarily display?

    <p>A graph of rock properties versus depth</p> Signup and view all the answers

    Which of the following is NOT a method to influence the estimation of hydrocarbon reserves?

    <p>Increasing pore fluid salinity</p> Signup and view all the answers

    What is petrophysical analysis primarily concerned with?

    <p>Calibrating log data with core analysis</p> Signup and view all the answers

    What characterizes a calibrated petrophysical analysis?

    <p>Comparison of porosity and saturation with core data</p> Signup and view all the answers

    How is log analysis typically described?

    <p>Art and science directed at data reduction and error reduction</p> Signup and view all the answers

    Why might well logs be used beyond oil and gas evaluation?

    <p>To evaluate mineral deposits like coal and potash</p> Signup and view all the answers

    What is an effect of compaction on electric current flow?

    <p>Reduces pathways for electric current flow</p> Signup and view all the answers

    What defines the axial plane in a fold?

    <p>An imaginary plane running through the fold axis.</p> Signup and view all the answers

    Which statement about anticlines and synclines is accurate?

    <p>Anticlines do not always correspond with topographic highs.</p> Signup and view all the answers

    What is the term for the distance that rocks on opposite sides of a fault have moved?

    <p>Slip.</p> Signup and view all the answers

    In the context of a fault, what does the term 'hanging wall' refer to?

    <p>The block that lies above the fault plane.</p> Signup and view all the answers

    How is a normal fault characterized?

    <p>The hanging wall moves down relative to the footwall.</p> Signup and view all the answers

    What is a fault zone?

    <p>A network of numerous closely spaced fractures.</p> Signup and view all the answers

    What occurs in faults regarding the movement of rocks?

    <p>Movement can be both gradual and sudden.</p> Signup and view all the answers

    What happens when rock moves along a fault after it forms?

    <p>New fractures are less likely to develop.</p> Signup and view all the answers

    Study Notes

    General Geology Course - First Year Students

    • Course offered by Prof. Adel Kamel Mohamed
    • Intended for first-year students at the Faculty of Education
    • Image of Earth's tectonic plates with labeled plate boundaries (Ring of Fire highlighted)

    The Earth's Layers

    • Earthquake waves change speed and direction at depth, revealing interior layers
    • Diagram shows Earth layers (crust, upper mantle, lower mantle, liquid outer core, solid inner core)
    • Oceanic crust (5-10 km thick) is primarily basalt, rich in iron and magnesium silicates
    • Continental crust (20-70 km thick) is primarily granite, with silicon oxides
    • Lithosphere includes the crust and upper portion of the mantle—relatively cool, hard, and strong
    • Asthenosphere is a weaker, plastic layer beneath the lithosphere
    • Mantle (2900 km thick) comprises most of Earth's volume—primarily ultramafic rocks (peridotite)
    • Core (Outer core: 2250 km thick, liquid; Inner core: 1220 km thick, solid) is primarily iron and nickel

    Review on Rocks

    • Sedimentary rocks: Formed from sediment (sand, shale, pebbles). Typically layered, soft, and may contain fossils (e.g., conglomerate, limestone).
    • Metamorphic rocks: Formed from existing rocks (pre-existing) under heat and pressure. Often have ribbon-like layers and/or shiny crystals (e.g., gneiss, marble).
    • Igneous rocks: Formed from cooling and solidifying magma or lava. Can be intrusive (formed below Earth's surface) or extrusive (formed above Earth's surface) (e.g., granite, basalt).

    Geologic Structures

    • Stress: A force exerted on an object.
      • Confining stress: Compresses rocks equally in all directions.
      • Directed stress: Compresses rocks strongly in one direction.
        • Compression: Shortens the distance.
        • Extension: Lengthens the distance.
        • Shear: Causes one part to slide past another.
    • Strain: The deformation produced by stress.
      • Elastic deformation: Rocks return to original shape.
      • Plastic deformation: Rocks retain new shape.
      • Brittle fracture: Rocks break.
    • Folds: Bends in rock, usually from compressive stress.
      • Anticline: Arching upward.
      • Syncline: Arching downward.
    • Faults: Fractures where rock has moved relative to each other.
      • Normal fault: Hanging wall moves down relative to footwall (caused by tension).
      • Reverse fault: Hanging wall moves up relative to footwall (caused by compression).
      • Thrust fault: Nearly horizontal reverse fault.
      • Strike-slip fault: Rocks move horizontally past each other.
    • Joints: Fractures where rock has not moved.

    Plate Tectonics

    • Tectonic plates: Large segments of the lithosphere that move slowly over the asthenosphere.
    • Divergent boundaries: Plates move apart, creating new crust (e.g., Mid-Atlantic Ridge).
    • Convergent boundaries: Plates move together -
      • Oceanic-continental: Denser oceanic plate subducts under continental plate, forming volcanoes and trenches (e.g., Western Aleutians)
      • Oceanic-oceanic: Denser oceanic plate subducts under less dense oceanic plate, forming island arcs and trenches (e.g., Western Aleutians).
      • Continental-continental: Plates collide, forming mountain ranges (e.g., Himalayas).
    • Transform boundaries: Plates slide horizontally past each other (e.g., San Andreas Fault).

    Earthquakes

    • Earthquakes: Sudden shaking of the Earth's crust caused by the release of stored energy.
    • Focus: The point within the Earth where the earthquake originates.
    • Epicenter: The point on the Earth's surface directly above the focus.
    • Seismic waves: Energy waves that radiate outward from the focus.
    • Body waves: Travel through Earth's interior.
      • P-waves (primary): Fastest, compressional waves.
      • S-waves (secondary): Slower, shear waves.
    • Surface waves: Travel along Earth's surface, responsible for most of the damage.
    • Liquefaction: The loss of shear strength in water-saturated soil during an earthquake.

    Tsunamis

    • Tsunamis: Giant waves generated by underwater earthquakes or landslides
    • Usually detected in open ocean by flat wave motion
    • Wave height increases significantly upon approach to shore

    Geophysical Methods

    • Methods used to locate and study the subsurface (magnetic, gravity, seismic, electrical resistivity, borehole logging)

    • Gravity Method-Detecting density differences in subsurface rocks by measuring changes in gravitational acceleration

    • Magnetic Method-Detecting differences in magnetic susceptibility in subsurface materials based on magnetic field anomalies.

    • Electrical Resistivity Method-Measuring varying physical properties in rocks and minerals to estimate subsurface structure via electrical currents.

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    General Geology Course PDF

    Description

    Explore the fascinating structure of the Earth in this quiz designed for first-year education students. Discover details about the Earth's layers, including the lithosphere, asthenosphere, and core. Test your knowledge on tectonic plates and the unique properties of oceanic and continental crust.

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