M1L2 - Geologic Timelines and Processes Flashcards
Origins of Earth
- Over 4.6 billion years ago, dust and gas get drawn together due to gravity while orbiting around a young sun
- Dust particles moving at different speeds collide, smash together and grow into larger and larger objects until some are planet size
- Large impacts provide substantial energy and initiates warming event, causing moon to be cast off
Formation of crust
As earth grew, the available material to collide diminished
Formation of atmosphere
Formed as result of releases of gas, held in place due to gravity
Ocean and water formation
Due to condensing and comets –> Life
Snowball earth
- Rapid cooling led to snowball earth
- Led to massive extinction (also allowed/forced evolution of new species
- Warming due to volcanoes and presence of greenhouse gasses
- Ongoing change throughout Earth’s history (3 times)
Combination of factors that caused cooling
- Reduction in greenhouse gasses because of increases in photosynthesis and the weathering of limestone
- Reduced incoming solar radiation
- Increased snow/ice formed, increasing albedo (reflectance)
How long have humans been around in earths’ history
0.04%
Different temporal scales (geochronologic units) from smallest to largest
- Eons
- Eras
- Period
- Epoch
what are different temporal scales based on
Broadly based on biota
Anatomy of Earth
- Crust
- Mantle
- Outer core
- Inner core
Crust
Thin outer layer
Mantle
- Predominantly solid interior of planet
- 84% of Earth volume
Outer core
- Liquid
- Iron and nickel rich
- Creates earths magnetic field
Inner core
- Solid
- Predominantly iron
Uppermist mantle
Called lithosphere and is comprised of tectonic plates
Composition of the earth
- Continental and oceanic crust are different
- Convection in liquid outer core drives tectonic plate movement
Types of boundaries
- Divergent (rift valleys, ocean ridges)
- Convergent (subduction and mountain/island building)
- Transform (tension build up and slip)
- Hot spots (from thinner parts in the crust)
Geologic activity
- Creates Earth we live on today
- Important for creating a hospitable environment and unique regions of Earth
- Influences snow and ice distribution
- Creates geographic features and unique environments
- Main driver of environmental change over long time periods
Types of bias
- Confirmation
- Publishing
- Observation
- Selection
- Recall
Confirmation bias
Looking for patterns that support the idea already held
Publishing bias
Negative results are harder to get published in peer-review
Observation bias
Where participants are aware of being observed and act differently as a result
Selection bias
Under or over representation of groups or specific characteristics
Recall bias
Interviewees remember and recall events differently
