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What is the ø of the earth?
8,000 miles
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What is the ø of the sun?
800,000 miles
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What is the earth circumference?
24,000 miles
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Describe Earth's 3 distinct, concentric layers:
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Describe 2 types of the Earth's Crust:
- Oceanic → Mafic → Basalt
- Continental → Felsic → Granitic
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Describe 3 sources of Earth's residual Heat:
- Gravitational energy
- Kinetic energy → planetesimal collisions
- Meteor impacts
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Heat from within the Earth is continually generated by:
Radioactive decay
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What is a Lithosphere and where is located?
Rigid outer layer containing "crust" & frozen part of the upper mantle
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What is the Asthenosphere and where is located?
- Partially melted upper mantle
- has plastic-like
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What is the Lower Mantle and where is located?
- Mesosphere
- Solid layer of rocks
- between the asthenosphere iron core
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What are the components of Earth's core and where are they located?
- Liquid Core
- Solid Iron Core
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What happened to most of the hydrogen and helium that accumulated with Earth's mass?
- Escaped
- Earth did not have enough gravity
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How much free oxygen was available very early in Earth's history?
Almost none
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What does the presence of pyrite grains in early sedimentary rocks imply?
Back then was no free oxygen because pyrite was not oxidized like in today's atmosphere.
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Describe the occurrence of "Banded Iron Formations" during early Earth times?
(2.5 - 2 billion yrs)
- BIF require abundant oxygen
- Therefore, during that time there must have been more free oxygen
- Became thick + cover vast areas
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Which ancient life forms were present at least 3.5 billion years ago that began creating Earth's fee oxygen?
Bacteria + Algae
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What is the approximate percentage composition of Earth's atmosphere today?
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What happened to most of the CO2 that was present in early Earth's atmosphere?
- small fraction converted to oxygen
- Seawater absorbed
- Microscopic plants + animals → skeletons → limestone
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How long did it take Earth's oceans to reach its current salinity levels?
early as the oceans formed
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Which scientific theory did Alfred Wegener proposed?
Continental Drift
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What is the current theory about the creation of Earth's magnetic field?
The solid core spins 2/3rd of a sec faster than outer liquid iron core
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What is paleomagnetism and why is an important tool?
The study of magnetic fields, as preserved in the magnetic properties of rocks
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Who proposed the theory of seafloor spreading?
Dr. H. H. Hess
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What are "Magnetic polarity stripes"?
parallel lines of polarity
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Compare the age of basalt at the oceanic ridge to its age at the edge far from the ridge
- older on both sides of the ridge
- youngest at the center of the ridge
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What is a tectonic plate?
A single block of lithosphere that moves about the Earth's surface
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Which tectonic zone can create an oceanic basin?
Divergent zones
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In which tectonic zone are all black smokers located?
- Mid-oceanic Ridge
- Spreading center
- Central rift zone
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What do we call a divergent zone on land?
Rift zone valley
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What are the three types of convergent zones?
- oceanic ↔ oceanic
- oceanic ↔ continental
- continental ↔ continental
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What is a subduction zone?
A locality where oceanic crust is being pushed or subducted into the mantle
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Where tectonically are the deep sea trenches located?
subduction zones
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What is the most favored theory today for plate tectonic movements?
Slab pull theory
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Give an example of a landmass created by a mantle plume or hotspot:
Hawaii
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Describe a super-continent cycle and who came up with the name?
- About every 500 million years, most of Earth's continents collide together, then later split apart.
- J. Tuzo Wilson
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How is science different from other fields of human endeavor?
Science searches for regularities and patterns in the natural world
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Why is that many aspects od being human are not amenable to scientific description?
Because of culture and opinion
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Which subjective "sciences" are not normally addressed by normal science?
- Justice + honor
- Esthetics + manners
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Questions that science can address are limited by...
- The proprieties of natural world
- Instrumentation
- Socially imposed missions
- The paradigm that guide scientific inquiry
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How absolute is scientific knowledge?
Not absolute
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