Physical Geology Final Exam Study Guide Notes

Physical Geology Final Exam Study Guide

Recurring Themes

• Uniformitarianism: The theory that changes in the Earth’s crust during geological history have resulted from the action of continuous and uniform processes.
• Plate Tectonics: The theory that Earth’s lithosphere is divided into large, rigid plates that move and interact, causing earthquakes and volcanic activity.
• Two Main Energy Sources Driving Earth's Processes: Sun and Earth’s core.
• Age of Earth: 4.6 billion years old.
• Geology: The study of Earth’s processes, history, physical features, and materials.

Groundwater

• Calculations: Be able to calculate porosity, permeability, and velocity for groundwater.
• Groundwater Movement: Primarily caused by gravity.
• Problems from Over-Withdrawal:
  • Lowered water tables
  • Decreased surface water levels
  • Increased pumping costs
  • Potential land subsidence
  • Cone of depression (dry well)
• Groundwater Flow Direction: High to low direction, perpendicular to contour lines.

Surface Water

• Stream Discharge: Be able to calculate stream discharge given the cross-section area and velocity.
• Velocity Calculation: V = \frac{distance}{time}
• Sediment Behavior with Velocity Changes:
  • Slows: Sediment deposited
  • Speeds up: Stream erodes and carries more sediment
• Valley Shape Cut by Stream: V-shape (downcutting).
• Rainshadow Effect: Mountain range blocks passage of moist air, resulting in lower precipitation on the downwind side of the mountain.

Mass Movements

• Mass Wasting Processes: Identify and describe processes in terms of water content, type of material moved, and speed (creep, slump, solifluction, earthflow, debris flow, rockfall, mudslide - slowest to fastest).
• Role of Water:
  • Increases weight of slope
  • Lubricates material
  • Faster movement
  • Reducing friction
• Triggers: Rainfall, earthquakes, human activity, volcanoes, snow melt.

Ocean and Coastal Geology

• Regions of the Continental Margin and Ocean Basins:
  • Continental Shelf: Shallow edge, starts at shore and goes out into the ocean.
  • Continental Slope: After the shelf, ocean floor drops, marks the edge of the continent.
  • Continental Rise: Bottom of slope, land flattens out, sediments pile up, making a gentle slope before the deep ocean floor.
  • Abyssal Plain: Flat, deep part of ocean floor, covered in mud.
  • Mid-Ocean Ridge: Underwater mountain range, formed by tectonic plates.
  • Seamount: Underwater volcanoes.
  • Ocean Trenches: Deepest part of the ocean, where one plate is pushed under another (subduction zone).
• Active vs. Passive Margin:
  • Active Margin: Tectonic plates move/converge past each other.
  • Passive Margin: Stable, distant from plate interactions.
• Longshore Current: Flows parallel to the coastline within the surf zone, moving water and sediment along the beach. Formed when waves approach shore at an angle, causing water to move in a zigzag pattern.
• Tidal Patterns: Differentiate tidal patterns (semi-diurnal, diurnal, mixed). Be able to calculate tidal range from a tide chart.
• Coastal Features:
  • Depositional: Beaches, spits and bars, barrier islands, dunes, mudflats, tombolos.
  • Erosional: Cliffs, headlands, wave-cut platforms.
  • Organic: Beaches, dunes, coral reefs, mangroves, marshes, wetlands.

Weather/Climate/Deserts

• Carbon Cycle: Process where carbon moves through Earth’s atmosphere, oceans, land, and living organisms.
  • Long-term Storage: Rocks and sediments.
  • Short-term Storage: Atmosphere, oceans, and living organisms.
• Greenhouse Effect: Warms the Earth’s surface; greenhouse gases trap heat from the sun, preventing it from escaping into space, keeping the planet at a sustainable temperature for life.
• Greenhouse Gases: Substances that trap heat in Earth’s atmosphere (methane, CO_2, water vapor, etc.).
• Proxy Data Used by Paleoclimatologists: Tree rings, ice cores, sediment from ocean and lakes, salt cores, and historical records.
• Desert Location by Latitude: Typically around 30 degrees north and south due to high pressure and near the equator (warm and dry).
• Atmospheric Circulation Influence on Deserts: Hadley cells circulate from the equator towards the poles, causing air to sink and dry out, creating high-pressure zones associated with deserts.
• Air Movement: High to low pressure.
  • High Pressure: Clockwise.
  • Low Pressure: Counterclockwise.

Glaciers

• Balance of Ablation and Accumulation: Accumulation and ablation (loss of ice) determine mass balance and whether or not a glacier shrinks, grows, or remains stable.
• Depositional and Erosional Features:
  • Depositional: Moraines, eskers, outwash plains, drumlins, glacial erratics, tills, arete
  • Erosional: U-shaped valley, cirque, aretes, horn, hanging valley, fjords, piedmont glacier.
• Types of Alpine Glaciers: Cirques, valley glaciers, piedmont glaciers, ice fields, and ice caps.
• Glacier Flow: Downslope due to gravity.
• Valley Shape Cut by Glacier: U-shape.
• Tools to Study Glaciers: Probes, GPS, cameras, ice cores, weather stations. Studied to understand climate change and sea level rise.

Cumulative Review

• Scientific Method: Distinguish between fact, hypothesis, theory, and law in earth science.
• Earth Systems: List and identify earth systems and how they interact.
• Plate Tectonics: Explain how plate tectonics accounts for the worldwide distribution of earthquakes, mountains, volcanoes, and trenches.
• Rocks and Minerals:
  • Rock Cycle: What is the rock cycle?
  • Rock Types: Name the different types of rocks, how do they form?
• Earth’s Resources: Renewable vs. Non-Renewable.
• Earthquakes: Evaluate the reasons for damage from a large earthquake. Identify types of earthquake damage.
• Volcanoes:
  • Types of Volcanoes:
    • Cinder: Small, steep-sided, cone shape with a bowl crater at the summit, single explosive eruptions made of ash and cinder.
    • Composite/Strato: Large, steep cone shape with hardened lava and volcanic ash, multiple eruptions over long periods, viscous lava.
    • Shield: Very large, broad gently sloping, effusive eruptions with fluid lava.
• Structures: Identify different types of faults and folds in pictures/diagrams. Which have brittle deformation? Ductile?
• Geologic Time: Be able to calculate half-life and identify relative ages/sequence of events of strata based on pictures/diagrams.

Concept Questions

1. Mass Wasting Events:
   • Triggers for Italy and Peru mass wasting events (at least 1 for each location).
   • Water's role in the Nevado Huascarán and San Fratello events.
   • Geological and climatological differences between the Nevado Huascarán and San Fratello sites.
   • How did geology and climate contribute to the development of the slide in both cases?
2. Rising CO_2:
   • Is rising CO_2 clearly a human-induced change?
   • Evidence to support that rising CO_2 may be natural (at least 1 discussed in class/videos).
   • Evidence to support that it is human-induced (at least 1 discussed in class/videos).
   • List 3 effects of global warming that we are seeing today.
3. Coastal Erosion Mitigation:
   • Describe 2 hard stabilization techniques and 1 soft stabilization technique used to mitigate coastal erosion/wave action.
   • Include why they are used (be specific to the technique) and the shortcomings of each technique listed.

Practice Problems

• Porosity:
  • \text{Porosity} = \frac{\text{amount of water}}{\text{amount of sediment}}
  • Each individual in the United States uses approximately 100 gallons of water each day for drinking, bathing, washing clothes, and other purposes. What volume of sand is in an aquifer that has 30% porosity and serves a community of 25,000 people? Hint: make sure to use all the numbers!
• Velocity:
  • V= k * i
  • \text{Velocity} = (\text{Permeability})(\text{Gradient})
  • Well X is 120m above stream level and 500 m away from the stream. How fast is the groundwater moving through sandstone with a (permeability of .2m/s) from the well towards the stream?
• Discharge:
  • Q=A*V
  • \text{Discharge} = \text{cross sectional area} * \text{velocity}
  • What is the discharge of a stream that is 10 feet across, 2 feet deep, and moving 25 feet/second?