Topic 2: Formation & Early evolution Flashcards
Describe the systems supporting life on Earth
- Located in a favorable orbit (Goldilocks Zone)
- Has liquid water
- Gravity (to keep water and gases near surface)
- Magnetosphere (protects hydrosphere and atmosphere from solar wind and radiation)
- Ozone layer (contributes to the positive feedback with photosynthesis)
- Plate tectonics (renewal of surface, water, gas)
What is the Goldilocks zone?
A habitable zone in our solar system in which temperature is not too low or too high for liquid water.
Describe the birth of our Sun
From a 1st generation star explosion, there was gas and dust cloud rotated by the impact of gravitational waves. Then, it went through extreme temperature and pressure, triggering condensation, ignitation, and fusion –> Sun (3rd generation star)
Describe the birth of our Solar System
At first, planets started out as liquid magma oceans. As they continued to orbit, the debris and dust were cleaned by solar wind, forming our solar system.
Describe the formation of the Moon
A Mars-sized planet collided with the Earth which made lots of materials get spilled out and essentially, formed the Moon.
Chemical segregation??
Heavy metals sank to form Earth core, and other rocks float to surface and form the layers of the Earth (mantle)
Where did water come from?
During convection, minerals in the mantle eject oxygen and hydrogen, which then recombine to form water at extreme depth. This water will lower the metling point of rocks which eventually melt. With lower density, these rocks float to surface to form volcanoes.
These volcanoes also pump lots of water vapour which condenses and form oceans.
Explain the positive feedback that generates ozone layer and oxygen.
Back then, there are only simple bacteria under the oceans, producing free oxygen molecules which much later, form the ozone layer. This ozone layer protects the Earth from solar wind and radiation, allowing in-land organisms and plants to appear. This presence of plants further increases the production of oxygen.
How was the magnetic field created and what is its role?
With the inner solid core super-rotation and outer liquid core convection, a phenomenon called geodynamo effect occured and created magnetic field.
This magnetic field protects our Earth from the Sun’s radiation
What are minerals?
Minerals are homogeneous chemical structure arranged in a crystal lattice.
What made up rocks and how many types of rocks are there?
A combination of different minerals create rocks.
3 types of rocks:
- Igneous: formed through melting and volcanic activity
- Metamorphic: formed with extreme heat and pressure
- Sedimentary: through deposit and erosion
What are fossils?
Fossils are remains or impression of once-living plants or animals. Fossils only preserve shape or impressions, NOT colour.
What can fossils be used for and in which environment can fossils be formed?
Functions of fossils:
1. Understand evolution
2. Needed in biostratigraphic dating and correlation
3. Paleographic reconstruction
For fossils to formed, they need to be buried quickly and be in an anoxic environment with no disturbance.
Describe paleogeography
Paleogeography is the study of the physical and biological geography of the geologic past.
What are trace fossils?
Trace fossils preserve animals’ behaviors (burrow, or tracks), act as “bioturbation indicators
