How long has the world existed?
4.6 Billion Years
Biggest difference between Geology vs. other sciences
Time
- not much happens to the earth over the course of 1 human lifetime
Rates of Geologic Processes
um/year to cm/year
How old are some fossils?
3.5 billion years
Atmosphere and hydrosphere formed?
4 billion years ago
When did Dinosaurs go extinct?
65 million years ago
How did the universe expand after Big Bang Theory?
Formed galaxies, planets, stars
Big Bang Theory - universe began…
14 billion years ago
Nebular Hypothesis
A large gas (nebula) cloud begins to condense and small eddies collide and become solid chunks
Formula for the Sun
H + H = He + Energy
Protoplanets
Bigger than current planets, eventually contract due to gravitational pull
Protoplanets vs. Terrestrial Planets
Terrestrial grew from collision of Planetesimals
Protoplanets = gas accretion
Saturn, Uranus, Neptune, Jupiter, Pluto, are all which kind of planets?
Outer Planets
Venus, Earth, Mercury, Mars, are all which kind of planets?
Inner Planets
James Hutton (1785) believed Earth was like a …
Superorganism
Gaia Hypothesis (James Lovelock)
- Earth is an organism
- Life consciously controls the environment and changes it to benefit us
5 Fundamental Concepts
1) Population Growth
2) Sustainability
3) System and change
4) Hazardous Earth Processes
5) Scientific knowledge and values
Population Growth Formula (Doubling time)
D = 70/G
What are earth’s 2 heating sources?
Inner core + Sun
4 Subsystems of the earth
- Lithosphere
- Atmosphere
- Hydrosphere
- Biosphere
Average Resident Time (formula)
T = S(stock) / F(average rate of transfer)
When does a theory become a law?
When there is no sensible way to challenge the theory (which has been proven via many hypothesis tests)
What is the atmosphere?
- All the gases surrounding earth
- Wind, clouds
- Atmosphere spreads water around the earth
What is the hydrosphere?
All the water in the world
Lithosphere
The earth’s crust (rocks, plates)
- Erosion turns rocks into soil
Biosphere
All the plants and animals in the world
4 Factors that lead to heating and melting
- Accretion of meter-sized bodies
- Collisions
- Compression
- Radioactivity of elements (uranium etc.)
What is the Core made of (100-200 million years after initial accretion)
Iron - melted and pulled to core
Earth’s composition
Fe + O + Si + Mg = 93%
Crust’s composition
Si + O + Al = 92%
Asthenosphere
Part of the mantle beneath the lithosphere
How many plates make up the earth’s outer crust?
20
Evidence for Dynamic Earth Theory
Mountain ranges, earthquakes in space, volcanos in space,
Continental Drift
Unified super-continent, pangaea shifting apart
- same fossils across both sides of Atlantic ocean
- rock distribution (matches up like a puzzle)
Seafloor spreading
Not a single static piece
- Existence of mid-oceanic ridges
- Continents float over spreading seafloor
- Paleomagnetic data
- age of seafloor rocks
- thickness of seafloor sediment
Plate Tectonics Theory
Plates move in relation to each other
- No movements within plates, just at plate boundaries
Significance of tectonic cycle
Global distribution of resources
- Patterns of earthquakes/volcanoes
What are hot spots centers for?
Volcanos…which have lava and magma originate from the deep mantle
- Chain of volcanoes over a change of plate motion
Plate Subduction can lead to?
Island arc + volcanic arcs
How is a hazardous event (like earthquake) measured?
Magnitude and frequency (which are generally inverse)
Risk of Hazard Formula
Probability of occurrence X consequence
Annual Loss of life from hazardous earth processes
150,000
What is an earthquake?
Movement of rocks past one another
Earthquake Fault
Locus of earthquake movement
Earthquake focus
Where initial earthquake began
Earthquake epicenter
point on surface right ABOVE the focus
Seismology
Study of energy released from earthquakes
- Source of wiggly lines that describe earthquake
2 Types of Earthquake Waves
P waves (compressional parallel) S Waves (shear perpendicular)
Richter Scale
Amount of energy received from epicenter