Geology chapter 1-4 exam questions and answers 2024

What is Geology "Earth knowledge" -Scientific study of our planet -Earth's history -Earth's composition -Earth's internal structure -Earth's surface features Sustainable Development Earth is a "spaceship" with limited resources and a delicate life-support system. "Sustainable Development": Current generation must ensure hospitable planet for future generations. The Roles of Geologists -Find and manage NATURAL RESOURCES -Understand Earth processes well enough to predict NATURAL HAZARDS -Protect the environment by understanding ENVIRONMENTAL AND GLOBAL CHANGE The Scientific Method A procedure used to discover how the universe works through systematic observations and experiments Principle of Uniformitarianism Processes that occur on modern Earth have worked in much the same way during the geologic past. Earths layers outer core, inner core, mantle, and crust The Inner Core -Primarily IRON and NICKEL -Solid The outer Core -Primarily IRON and NICKEL with sulfur and oxygen -Liquid The Mantle -Primarily SILICATES (silicon and oxygen) with abundant magnesium -Plastic-like solid The Crust -Primarily SILICATES (silicon and oxygen) with abundant aluminum -Rigid solid Earth as a System -Open system: Exchange energy and mass -Two primary sources of energy: 1. Solar 2. interior Earth -Open and interacting geosystems -Positive and negative feedbacks between the systems Geodynamo System -Magnetic field generated by convection in the outer core -Magnetic reversals have occurred in the past. Cause: interaction between inner and outer cores Plate Tectonic System -Convection in the mantle drives the movement of Earth's surficial plates. Note: Plates are composed of lithosphere, which is the crust and upper, rigid mantle. Continental Drift -Alfred Wegener (1915) proposed that all of the continents were once part of a large supercontinent - Pangaea. Based on: -Similarities in shorelines -Terrestrial geologic evidence -Distinctive fossil groups found in Africa and South America Paleontological Evidence -No mechanism to transport across ocean -Divergence of species following break-up ex. Mesosaurus in Africa and South America Pangaea Early Jurassic, 195 Ma Late Jurassic, 152 Ma Late Cretaceous, Early Tertiary, 66 Ma Problems with Continental Drift -Wegener proposed a mechanism for drift: a.Continents plowed through solid ocean floor, b.Tidal forces drove the motion, -Tidal forces are know to be too weak to move continents. -However, the hypothesis was largely rejected due to an inadequate mechanism of continental movement. Seafloor Spreading -Original evidence for continental drift was from continental rocks. -Technological advances in the 1940s, 1950s, and 1960s allowed investigation of the seafloor. -New data provided intriguing new information! Geology of the Ocean Floor Bathymetry of the ocean basins: -Sonar revealed ridge system in ocean basins. -Ridge system is continuous around the entire globe. -There is a central rift VALLEY within the ridge. Seafloor Spreading: Testing the Hypothesis Magnetic anomalies record symmetric patterns of magnetism on either side of mid-ocean ridges. -Positive anomalies correspond with seafloor formed during times of NORMAL polarity. -Negative anomalies correspond with seafloor formed during times of REVERSED polarity. Plate Tectonic Theory -The surface of Earth (lithosphere) is divided into individual hard, continuous shells called plates. -The plates move about, with deformation confined to the boundaries of plates. Plate Tectonic As plates move around the globe, their edges interact with one another at the boundaries. There are three types of plate boundaries: -Divergent boundaries -Convergent boundaries -Transform margins Divergent Boundaries Two varieties: Oceanic plate separation -Mature Continental plate separation -Juvenile Divergent Boundaries (Oceanic) -As oceanic lithosphere spreads apart, new seafloor is created through volcanic processes. -Ocean basin gradually grows as volume of oceanic crust increases. -Shallow earthquake focus depths Divergent Boundaries (Continental) -Early stages of divergence -Continental rifting will lead to a break-up of continents and the formation of new oceans. -Shallow earthquake focus depths Convergent Boundaries Three varieties: Ocean - Ocean convergence -Subduction Ocean - Continent convergence -Subduction Continent - Continent convergence -Collision Convergent Boundaries (Ocean - Ocean) -Subduction (recycling) of denser oceanic plate -Volcanic island arc forms on non-subducting plate. -Earthquake focus depths range from shallow to deep. Convergent Boundaries (Ocean - Continent) -Subduction (recycling) of oceanic plate -Volcanic mountain belt forms on continent. -Earthquake focus depths range from shallow to deep. Convergent Boundaries (Continent - Continent) -Continental lithosphere cannot recycle. -Over-thickening of lithosphere and large mountain ranges result. -Severe earthquakes Transform Fault Boundaries Two varieties: -Mid-ocean ridge transform fault -Continental transform fault Mid-ocean Ridge Transform Due to the spherical nature of Earth, divergent boundaries are broken with a step-like pattern, resulting in transform motion. Continental Transform Plates slide against one another on land and lead to large earthquakes. How Fast Do the Plates Move? Typical relative plate velocities are between 5-150 mm/year. How do we know this? Velocity = Distance over Time Method #1: Seafloor Ages -Distance: Scale bar is used to determine distance between isochrons.