3.1 Planetary Geology Flashcards
When was the earth formed?
The whole solar system is 4600 million years old
Earth is 4.5 billion years old
How was the earth formed?
The solar system formed from the same material
A cloud of dust and grains formed the rocky planets that circle closest to the sun
All the grains collided to form small planets
The asteroid belt is made up of the small rocks that didn’t form planets
Meteorites provide evidence of how earth formed and what earth formed from
What is the iron catastrophe and how does it help explain the earth’s formation?
The early earth was completely molten
Allowed elements like zinc and iron to sink and form the core
Lighter elements floated and formed the crust
The magnetic field from the iron protect the earth’s atmosphere
How does mars compare to earth?
It is smaller than earth
It cooled faster and its core solidified so lost its magnetic field and atmosphere due to solar radiation
Less active plate tectonic system
Formed at same time from same materials as earth
Likely to have same structure
How does the moon compare to the earth?
The moon is chemically identical to earth
Must have formed from same materials
Formed when a smaller planet collided with the earth causing the debris to be sent into orbit. This made the debris join together to form the moon
This impact also caused the earth to grow in size
How did the moon form?
A small planetesimal set on collision course with earth
Planetesimal collided with earth
Earth and planetesimal debris from collision starts to orbit
Earth now bigger and tilting.
Debris in orbit starts to join together
Largest piece of debris has gravitational force to attract all other pieces to form the moon
How is the moon structured?
- No atmosphere
- No running water
- No plate tectonics
- No rock cycle
Why does the moon surface have more craters than the earth?
Moon surface heavily cratered caused by meteorite impact over past 4 billion years
Expect earth to have even more due to size and gravity BUT
Rock cycle - weathering, erosion, transport, deposition fills in and wears down craters
Atmosphere - meteorites burn up due to friction and reduce in size
Plate tectonics- oceanic crust recycles and continental crust deforms removing evidence of craters
What can we assume about mars based on its size?
Mars is smaller - cooled more quickly than earth
Means no magnetic field
No atmosphere due to solar radiation
Less active plate tectonics
Formed same time as earth from same material
Same structure: crust, mantle and core
Explain the land forms on mars?
Rift Valley
Suggest rivers, faults or tectonics
Rivers fast flowing lots of erosion and high energy
Q - what if a Rift Valley?
Land forms on mars - cross bedding
Suggests rivers Slow flowing and low to moderate energy Asymmetrical ripples Wind blowing may caused cross bedding Interpretation -> mars had thicker atmosphere and flowing water
Land form on mars - lava flow/landslides/river
Lava suggests vents from volcanoes - volcanic activity
Landslide suggest plate tectonics- convergent plate boundaries
Rivers suggest rainfall or snow melting - lots of water
Land form on mars - volcano/crater
Volcano has viscous lava so could be lava flow -> volcanic activity
Crater formed by asteroid impact -> meteorite activity - must have had gravity that would pull the meteorites in
Valleys or channels
These create shadows from the sun which looks like cooled magma
Valleys - rivers and lots of erosion or weather eg rainfall
Cooled magma - lava flow, volcanic activity
Desiccation cracks
Sand dunes
Desiccation cracks - evaporation of solutions -> hot desert environment with lots of water
Sand dunes - wind blowing sand forms dunes - thicker atmosphere on mars
