Earth Tectonics & Science
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What is the ø of the earth?
What is the ø of the sun?
What is the earth circumference?
Describe Earth's 3 distinct, concentric layers:
Describe 2 types of the Earth's Crust:
- Oceanic → Mafic → Basalt
- Continental → Felsic → Granitic
Describe 3 sources of Earth's residual Heat:
- Gravitational energy
- Kinetic energy → planetesimal collisions
- Meteor impacts
Heat from within the Earth is continually generated by:
What is a Lithosphere and where is located?
Rigid outer layer containing "crust" & frozen part of the upper mantle
What is the Asthenosphere and where is located?
- Partially melted upper mantle
- has plastic-like
What is the Lower Mantle and where is located?
- Solid layer of rocks
- between the asthenosphere iron core
What are the components of Earth's core and where are they located?
- Liquid Core
- Solid Iron Core
What happened to most of the hydrogen and helium that accumulated with Earth's mass?
- Earth did not have enough gravity
How much free oxygen was available very early in Earth's history?
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.
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
Which ancient life forms were present at least 3.5 billion years ago that began creating Earth's fee oxygen?
Bacteria + Algae
What is the approximate percentage composition of Earth's atmosphere today?
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
How long did it take Earth's oceans to reach its current salinity levels?
early as the oceans formed
Which scientific theory did Alfred Wegener proposed?
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
What is paleomagnetism and why is an important tool?
The study of magnetic fields, as preserved in the magnetic properties of rocks
Who proposed the theory of seafloor spreading?
Dr. H. H. Hess
What are "Magnetic polarity stripes"?
parallel lines of polarity
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
What is a tectonic plate?
A single block of lithosphere that moves about the Earth's surface
Which tectonic zone can create an oceanic basin?
In which tectonic zone are all black smokers located?
- Mid-oceanic Ridge
- Spreading center
- Central rift zone
What do we call a divergent zone on land?
Rift zone valley
What are the three types of convergent zones?
- oceanic ↔ oceanic
- oceanic ↔ continental
- continental ↔ continental
What is a subduction zone?
A locality where oceanic crust is being pushed or subducted into the mantle
Where tectonically are the deep sea trenches located?
What is the most favored theory today for plate tectonic movements?
Slab pull theory
Give an example of a landmass created by a mantle plume or hotspot:
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
How is science different from other fields of human endeavor?
Science searches for regularities and patterns in the natural world
Why is that many aspects od being human are not amenable to scientific description?
Because of culture and opinion
Which subjective "sciences" are not normally addressed by normal science?
- Justice + honor
- Esthetics + manners
Questions that science can address are limited by...
- The proprieties of natural world
- Socially imposed missions
- The paradigm that guide scientific inquiry
How absolute is scientific knowledge?
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