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Details Title Planet Earth Test 2 Description Test 2! Total Cards 71 Subject Geology Created 11/03/2011

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Cards

Term Absolute Age Dating	Definition When you assign a numerical age date
Term Isotopes	Definition Different varieties of an element that differ in the number of neutrons in the nucleus (giving them a different atomic weight)
Term Atomic weight is determined by...	Definition The number of protons and number of neutrons
Term Why do some isotopes decay?	Definition They are unstable so shed material
Term Decay	Definition Loss of protons and/or neutrons and energy is released
Term Parent isotopes decay into...	Definition Daughter isotopes
Term Half Life	Definition Time required for a parent isotope to decay to half of its original amount
Term Describe the 3 steps required to date a rock	Definition 1- Measure the parent isotopes remaining and the daughter isotopes produced 2- Determine how many half lives have passed 3- Multiply the number of half lives by the years of the half life of the element
Term Plate tectonics	Definition Theory that describes the movement of plates of lithosphere over the top of the asthenosphere
Term In the 20th century, Wegner proposed...	Definition That continents moved through time (continental drift)
Term What evidence supported Wegner's idea of continental drift?	Definition -Matching coastline shapes -Same rocks (same age/deformation) are present on separated landmasses -Same fossils are present on separated land masses -Evidence of past continental glaciation at present day low lattitudes
Term What were a few problems with Wegner's idea of continental drift?	Definition There was no known driving mechanism and no knowledge of Earth's interior
Term Paleomagnetism	Definition Study of Earth's ancient magnetic field
Term How does Earth's magnetic field teach us about the Earth's past?	Definition The field can impart magnetism to iron-rich minerals, aligning them with the North Pole. These minerals then crystallize and keep a record of which way North was at the time of their formation
Term What have we learned from paleomagnetism?	Definition -Polar wandering curves verified continental motion -Magnetic anomalies were discovered in the ocean crust,showing that not just the continents are in motion
Term Harry Hess was interested in the history of ocean basins. What were a few things he proposed?	Definition -The formation of the ocean crust (lithosphere) was caused by sea floor spreading -Old oceanic lithosphere is recycled at subduction zones -Mantle convection is the driving force for tectonic movement
Term Harry Hess proposed that mantle convection was the driving force for plate tectonics, but the modern understanding is that...	Definition Tectonic plates are causing mantle convection
Term What is some confirming evidence for plate tectonics?	Definition -Absolute age dating of the ocean crust shows that it is young -Earth's heat flow -Earthquakes and volcanic eruptions correspond to plate boundaries -Plate motion now monitored from space
Term Tectonic plates are composed out of...	Definition Oceanic lithosphere and continental lithosphere
Term What are plate boundaries?	Definition Where plates interact
Term Divergent boundaries are where...	Definition The plates pull apart in opposite directions
Term Convergent boundaries are where...	Definition Plates move towards one another
Term Transform boundaries are where...	Definition Plates slide past one another
Term What are some features of divergent boundaries?	Definition -Reduces pressure on mantle material and causes melting -Melting causes volcanic activity -New oceans form and widen over time -Common but moderate earthquake activity
Term What are some features of a convergent boundary?	Definition -Subduction occurs where there's different plate densities -Suturing occurs if the two plates are the same densities
Term In a convergent boundary, what is involved in an ocean-continent collision?	Definition -Subduction of oceanic lithosphere -Very large earthquakes, sometimes forming tsunamis -Magma forms above subduction zone, creating a continental arc with explosive volcanism
Term In an ocean-ocean convergent plate boundary...	Definition -Subduction of oceanic plates with greater density (they're older and colder) -Very large earthquakes, sometimes causing tsunamis -Magma forms above a subduction zone -Island arcs can form
Term In a continent-continent convergent plate boundary...	Definition -No subduction zones are created due to the equal densities of the plates -Suturing of landmasses occur -Large earthquakes -Mountains can be formed
Term In transform plate boundaries, what is the slide and grind also known as?	Definition Slide- "creep" Grind- "stick slip"
Term Transform plate boundaries separate other plate boundaries. What are some features of this?	Definition -Occurs mostly on the mid ocean ridges -Many moderate earthquakes -There are more severe if plate boundary cuts through continental lithosphere
Term The Hadeon and Archean Eons covered how much of Earth's history?	Definition 45%
Term The Hadeon and Archean eons are difficult to study because...	Definition There is a very poor rock and fossil record
Term What are the most important things to happen during the Hadeon and Archean Eons?	Definition Formation of the Earth and it's oceans, atmosphere, moon, and the beginning of life
Term The formation of the solar system is described by the _______ hypothesis.	Definition Nebular
Term Nebula	Definition An interstellar cloud of dust and gas
Term Describe the nebular hypothesis	Definition Going from a cloud of particles to a recognizable solar system
Term Early Earth was described as a "________," what were some of it's features?	Definition "Protoearth;" -It was hotter, larger, and mostly liquid -It was well mixed (not layered) and lifeless
Term The cooling and solidification of the early Earth caused...	Definition Density differentiation until it became a layered Earth
Term What is the leading theory as to how our moon was formed?	Definition A glancing blow from a Mars-sized object hit Earth, and the resulting debris coalesced into the moon
Term What was the atmosphere like for the early Earth?	Definition ProtoEarth had leftover nebular gasses (mostly Hydrogen and Helium) which were blown away by solar wind
Term Our permanent atmosphere is mostly caused by...	Definition Volcanic outgassing (mostly water vapor, Hydrogen, Carbon Dioxide, Nitrogen, and Sulfur)
Term Our permanent oceans are from...	Definition Condensation
Term The first continents formed from...	Definition The separation of felsic and mafic magmas
Term Name and describe two Archean rocks	Definition -Greenstone Belts: old ocean crust, metamorphosed in continental collisions -Banded Iron Formations: Formed under weak oxidation conditions
Term The first life had to be __________, why?	Definition Less than 4 billion years ago, because our planet was inhospitable before that
Term When was the first isotopic evidence of life?	Definition 3.8 Ba
Term When do our oldest fossils date from?	Definition 3.5 Ba
Term Define "Abiogenesis"	Definition Study of the origin of life
Term The Miller-Urey experiments...	Definition Modeled conditions for first life
Term First life was _________ and lived by....	Definition Prokaryotic; absorbing organic compounds
Term Stromatolites are built by _______, and are important to know because....	Definition Cyanobacteria; Cyanobacteria require photosynthesis, which releases oxygen. They begin the process of making our atmosphere what it is today
Term What are the three most important things about the Proterozoic Eon?	Definition -Formation of large cratons -First eukaryotes and first multicellular organisms emerge -First record of major glaciations
Term Which was the first dominant life form in the Proterozoic eon?	Definition Cyanobacteria
Term How did the first eukaryote form?	Definition The absorption (but not digestion) of one prokaryote by another
Term What were the first multicellular organisms?	Definition Ribbon algae
Term Fossils of more complex animals occurred during the...	Definition Late proterozoic
Term Ediacaran fauna refers to...	Definition Soft part preservation
Term The assembly of Laurentia occurred when?	Definition About 1.85 Ba
Term Laurentia was the craton of which two landmasses?	Definition North America and Greenland
Term What is the current estimate for the number of times supercontinents formed in the Proterozoic?	Definition 3
Term The supercontinent Rodinia formed ____ and split around ______	Definition Around 1 Ba; 800 Ma
Term Rodinia split to form what four continents?	Definition 1-Laurentia 2-Siberia 3-Baltica 4-Gondwanaland
Term What is the idea of "Snowball Earth" and what evidence is there to support it?	Definition That the Earth at one point was completely covered in ice; there is good evidence for glacial deposition that is found globally
Term Name the layers of the Earth in order, starting at the innermost layer	Definition 1-Inner Core 2- Outer Core 3- Mesosphere 4- Asthenosphere 5- Lithosphere
Term Which layers of the Earth are rigid?	Definition Inner Core, Mesophere, and Lithosphere
Term What layer of the Earth is plastic?	Definition Asthenosphere
Term What layer of the Earth is liquid?	Definition Outer core
Term What is currently happening to the Earth's magnetic field?	Definition It's getting weaker as it prepares for a flip. Pockets of reverse polarity have appeared in the upper and lower lattitudes
Term What do scientists use to determine past strengths of the magnetic field?	Definition Iron-rich minerals, which align themselves with the current north pole then crystallize, keeping the alignment
Term What can be used to model the Earth's core?	Definition Liquid metal, Na being an excellent example because of it's low melting point
Term What do ancient lava flows in the continental US tell us about the rate of magnetic reversals?	Definition That they occur once every 200,000 years

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