earth science
Geologic Time and Earth History
What is the difference between relative and absolute dating?
Relative dating determines the order of events without specific dates.
Absolute dating provides an exact age using techniques like radiometric dating.
What are the major principles that allow for relative dating of rock layers?
Law of Superposition: Older layers are below younger ones.
Original Horizontality: Layers are deposited flat.
Cross-Cutting Relationships: Features cutting through layers are younger.
Inclusions: Pieces within a rock are older than the rock itself.
Fossil Succession: Fossil assemblages succeed each other predictably.
What is the most common technique for absolute dating? How does it work?
Radiometric dating: Measures the decay of radioactive isotopes like Carbon-14 or Uranium-238 to calculate the rock’s age.
What does each Eon and Era generally look like?
Hadean: Formation of Earth.
Archean: First life (prokaryotes).
Proterozoic: Oxygen buildup, multicellular organisms.
Phanerozoic: Abundant complex life, divided into Paleozoic (marine life), Mesozoic (dinosaurs), and Cenozoic (mammals).
What are the major events, when (general period) did they occur, and what caused them?
Cambrian Explosion: ~540 MYA, rapid evolution of life forms.
Great Dying: ~252 MYA, volcanic activity.
Great Oxygenation: ~2.5 BYA, cyanobacteria.
K-T Extinction: ~66 MYA, asteroid impact.
The Great Ice Ages: ~2.5 MYA to now, periodic cooling cycles.
First Life on Earth: ~3.8 BYA, simple cells.
Extensive Coal Swamps: ~300 MYA, Carboniferous period.
Hydrologic Cycle, Rivers, and Glaciers
What are the major reservoirs and processes of the hydrologic cycle?
Reservoirs: Oceans, glaciers, groundwater, lakes, atmosphere.
Processes: Evaporation, condensation, precipitation, infiltration, runoff.
How is sediment transported by streams?
Solution: Dissolved materials.
Suspension: Fine particles in the water.
Bedload: Larger particles rolling or bouncing along the bottom.
How do gradient, velocity, discharge, and channel size/shape change from headwaters to the mouth of a river?
Gradient: Decreases.
Velocity: Increases.
Discharge: Increases.
Channel shape: From narrow and V-shaped to wide and U-shaped.
What are the depositional and erosional features that you can find in or around a river?
Depositional: Deltas, point bars, floodplains.
Erosional: Cutbanks, waterfalls, canyons.
What is a flood? What are they usually caused by?
A flood occurs when water overflows onto normally dry land, often caused by heavy rainfall, snowmelt, or dam failures.
How do glaciers form?
Glaciers form when snow accumulates, compresses into ice, and moves due to gravity.
What are the major differences between ice sheets and alpine glaciers?
Ice sheets: Large, continental, and flow outward.
Alpine glaciers: Smaller, in mountain valleys.
What are the main erosional and depositional features from glaciers? What do their valleys look like (compared to river valleys)? Which features tell you how big a glacier used to be?
Erosional: U-shaped valleys, cirques, arêtes.
Depositional: Moraines, drumlins, eskers.
U-shaped valleys show glacier size compared to V-shaped river valleys.
Groundwater, Oceans, and Coastal Processes
How is water stored underground? What are the zones of groundwater?
Water is stored in pores/fractures.
Zones: Saturated (below water table), unsaturated (above water table).
What is the difference between porosity and permeability?
Porosity: Space available for water.
Permeability: Ability of water to flow through.
What is the difference between an aquifer and an aquitard; confined and unconfined aquifer?
Aquifer: High permeability; stores water.
Aquitard: Low permeability; restricts water flow.
Confined: Sealed layers above and below.
Unconfined: Open to surface.
What are the major challenges associated with groundwater?
Overuse, contamination, and saltwater intrusion.
What are beaches made of?
Sand, gravel, shell fragments.
What are the major depositional and erosional shoreline features?
Depositional: Spits, barrier islands.
Erosional: Cliffs, wave-cut platforms.
How do we measure and map the ocean floor?
Sonar, satellite altimetry.
What are the provinces of the ocean floor?
Continental shelf, slope, abyssal plain, mid-ocean ridges.
What are the layers within the ocean? How are they defined? Do you find them everywhere or only in some areas?
Layers: Surface (mixed), thermocline (temperature drops), deep (cold). Found globally, but their thickness varies.
What sorts of data and research is done onboard the JOIDES Resolution?
Sediment cores for climate, plate tectonics, and ocean history.
Weather and Climate
What are the layers of the atmosphere? How does temperature and density change in the layers of the atmosphere?
Layers: Troposphere, stratosphere, mesosphere, thermosphere.
Temperature and density decrease with altitude, except in inversions (stratosphere).
What is albedo?
Albedo is the reflectivity of a surface (e.g., snow reflects more sunlight).
What is a front? How can we tell different types of fronts? How does each affect the weather?
Front: Boundary between air masses.
Cold: Thunderstorms.
Warm: Steady rain.
Stationary: Long-lasting clouds.
Occluded: Complex storms.
What are the natural drivers of climate change?
Orbital changes, solar activity, volcanic eruptions.
How do positive and negative feedback loops work?
Positive: Amplify changes (e.g., ice melt lowers albedo).
Negative: Stabilize systems (e.g., increased CO2 boosts plant growth).
How do geoscientists study paleoclimate? What is the type of data they use called and what are some examples of that type of data?
Proxy data: Ice cores, tree rings, sediment layers.
How is the climate currently changing in comparison to over geologic time?
Warming faster than in natural cycles, with human influence.
What effects can we see from the currently changing climate?
Melting ice, sea level rise, extreme weather events.
Astronomy
What is the difference between the heliocentric model and the geocentric model?
Heliocentric: Sun-centered.
Geocentric: Earth-centered.
What are Kepler’s laws of planetary motion?
Elliptical orbits, equal areas in equal time, period-distance relationship.
What are the two types of planets in our solar system? How do they differ? What are they made of? Where can you find them?
Terrestrial: Rocky, inner (e.g., Earth).
Jovian: Gas giants, outer (e.g., Jupiter).
Why might a planet have extreme changes in temperatures? Or very little changes in temperatures?
Atmosphere thickness and distance from the Sun.
Why is Pluto not defined as a planet?
Does not clear its orbit of other debris.
What is the difference between a meteoroid, meteor, and meteorite? What is an asteroid? A comet? Where are they typically found?
Meteoroid: In space.
Meteor: Burning in atmosphere.
Meteorite: Hits Earth.
Asteroid: Rocky, in asteroid belt.
Comet: Ice, in outer solar system.
What does the phase of the moon tell you?
Position relative to Earth and Sun (e.g., new moon, full moon).
How long have people been studying the stars?
Thousands of years.
What is a galaxy? What galaxy do we live in?
Galaxy: Large system of stars. We live in the Milky Way.
What are the different types of stars? What is the life cycle of a star? What type of star is our Sun? How far is it through its life? What will happen when it dies?
Types: Main-sequence, giants, dwarfs.
Sun: Main-sequence, halfway through its 10 billion-year life, will become a red giant, then a white dwarf.
Where do neutron stars come from? Where do black holes come from?
Neutron stars: Supernova collapse.
Black holes: Extreme collapse of massive stars.