Understanding Earth EXAM 1
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Dr. Iqubal UNI
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67 Terms
Bybp meaning
billion years before present
When did the earth form?
4.6 bybp
Planetary differentiation
the earth changing, homogenous to layered
When did the big bang happen?
13.7 bybp
What was the big bang?
a cosmic explosion of all matter in the universe
Nebular hypothesis
the solar system formed from a rotating cloud of gas and dust that dispersed hydrogen/helium and the materials similar to Earth’s
What does a nebula form?
a disk of gas and matter with a proto sun
Planetesimals
kilometer sized chunks that will one day form planets
What comes after the disk with a proto sun in the nebula hypothesis
an enveloping disk of gas and dusts with platestimals
When Earth formed was it homogenous or layered?
homogeneous
What three mechanisms could have caused Earth to melt after being formed?
accretion, gravitational compression, radioactivity
Accretion
the planet was hit repeatedly and increased the temperature
Gravitational compression
gravity increases pressure as it pulls things towards the center
Radioactivity
atoms being broken spontaneously causes heat
Layers of the Earth
crust, mantle, core
Core
the heaviest elements
Crust
has the lightest elements
Mantle
a mix of both light and heavy elements
How did the atmosphere form?
planetary differentiation, trapped gas moved past the surface of the planet but were kept close by gravity
When did the atmosphere form (without oxygen)?
2.4 bybp
Continental distribution
tectonic plates shift and move and then move the continents with them
How did the moon form?
the earth was impacted and it launched matter into space, it formed its own gravity and continued to orbit the earth
Why is the earth tilted?
the impact that formed the moon caused a 23 degree tilt
Convection cell
the rotating movement under tectonic plates that influences the direction of their movement
Divergent plate boundary
movement of two plates away from each other, forms oceans (Africa and South America)
Convergent plate boundary
movement of plates together, forms mountains (indian plate to Eurasian plate)
How thick is the crust in the ocean?
7km
How thick is the crust on land?
40km
How thick is the mantle?
2850km
What are the two segments of the core?
inner and outer core
How thick is the outer core?
2260km
How thick is the inner core?
1220k
At what depth is the inner core/ center of the Earth?
6370km
At what depth is the bottom of the outer core?
5150km
At what depth is the bottom of the mantle?
2890km
Is the inner or outer core liquid?
outer core
Is the inner or outer core solid?
inner core
What is the sublayer of the mantle called?
Asthenosphere
Asthenosphere
a semi solid layer of rock within the mantle, what the tectonic plates sit on, movement is caused by local heat and pressure
Lithosphere
all the crust and part of the mantle, everything above the Asthenosphere
Element
pure substances found naturally
Mineral
elements combined
Rock
minerals combined
What percentage of the Earth is iron?
35%
What percentage of the Earth is oxygen?
30%
What percentage of the Earth is silicon?
15%
What percentage of the Earth is magnesium?
13%
What percentage of the Crust is oxygen?
46%
What percentage of the Crust is silicon?
28%
What percentage of the Crust is aluminum?
8%
What percentage of the Crust is iron?
6%