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What is the age of the oldest intact rocks that have been found on Earth?
4 Ga
How does the Doppler Effect tell us about the motion of galaxies?
Light from galaxies moving away from us has a lower frequency (I.e. looks redder) than light from galaxies that are moving towards us.
The earliest matter in the universe was composed of mostly
hydrogen and helium
The earth is referred to as a layered planet because
differentiation during and following planetary accretion allowed the materials making up the early Earth to separate based upon their density
What is the most probable origin of earth's moon?
condensed from material expelled from a gigantic collision between the proto-earth and a Mars-size impacting body
According to current scientific understanding, the age of our universe is
about three times older than the age of the earth
All of the following statements about the atmosphere of the early Earth are correct except one. Which statement is incorrect?
The development of Earth's magnetic field caused the atmosphere at that time to be driven off.
The Earth's layers are composed of which of the following, from outside to inside
(Si,Al,O); (Mg,Fe,Al,O); (Fe,Ni)
What information can meteorites provide about Earth?
the composition of Earth's core, Earth's age, the average composition of the whole Earth
According to nebular theory, the progression from planetesimal to full-fledged planet is propelled mainly by which of the following?
gravity
Alfred Wegner is best remembered for
being the first to put together a hypothesis for continental drift based on a variety of scientific data sources
Which part of the earth do geophysicists think generates it magnetic field? The earth's
core
Which statement about magnetic reversals is correct?
Reversals are random; we cannot predict when the next reversal will occur.
Magnetic declination refers to
the angular difference between a compass reading at a certain location and the direction of the True, or Geographic North Pole
Why can the earth's inner core not act as a permanent magnet?
Its temperature is far hotter than the Curie temperature for any magnetic material
If a flow of basalt were to cool and crystallize at the magnetic South Pole, what would be the orientation of its locked-in magnetic lines of force?
vertical to the earth's surface
Over the past 30 thousand years, what has been the relationship between the North magnetic pole and North geographic (rotational) pole?
Although the geographic pole is constantly moving in random directions, it always stays near to the magnetic pole
The geodynamo generates currents within the liquid outer core that are responsible for
generating most of the earth's magnetic field
Which one of the following is not a piece of evidence used by Wegner to argue for continental drift?
magnetic reversals in ocean floor basalts show a mirror imagine across mid ocean ridges
The difference between a theory and a hypothesis is
a theory is well tested
What takes place in convergent boundaries?
Deep and shallow earthquakes, recycling of old oceanic crust, and volcanic arcs
What takes place in divergent boundaries?
New oceanic crust and shallow earthquakes and volcanic activity
What takes place in transform boundaries?
Earthquakes but no volcanic activity
1st step of continental rift formation
The lithospheric mantle begins to stretch horizontally and thin vertically
2nd step of continental rift formation
The crust fractures, and faults develop
3rd step of continental rift formation
Large fault blocks of crust slide down into the widening rift
4th step of continental rift formation
Magma erupts as lava, creating volcanoes along and near the center of the rift
What is true about Hawaii's Hot Spot
It produced the Hawaiian Islands and it produced the Emperor Seamounts
What formed the Red Sea?
rifting followed by seafloor spreading
transfrom boundary
slides past each other
convergent boundary
moves toward each other; subduction
divergent boundary
moves away from each other; rifting/ seafloor spreading
1st event that occurs between the mid-ocean ridge and deep-ocean trench
oceanic crust created
2nd event that occurs between the mid-ocean ridge and deep-ocean trench
sediment accumulates on oceanic crust
3rd event that occurs between the mid-ocean ridge and deep-ocean trench
oceanic crust scraped off plate to form accretionary wedge
4th event that occurs between the mid-ocean ridge and deep-ocean trench
oceanic crust recycled into mantle
1st step on how scarps typically form at a mid-ocean ridge
asthenosphere rises beneath the ridge and begins to melt
2nd step on how scarps typically form at a mid-ocean ridge
magma rises and accumulates under the ridge axis
3rd step on how scarps typically form at a mid-ocean ridge
cooling causes the formation of gabbro and basalt dikes
4th step on how scarps typically form at a mid-ocean ridge
oceanic crust moves (spreads) away from the ridge axis
5th step on how scarps typically form at a mid-ocean ridge
tension causes breaks and results in the formation of faults
6th step on how scarps typically form at a mid-ocean ridge
slipping causes divergent-boundary earthquakes
The oldest seafloor is generally less than 200 million years old. Why?
All oceanic lithosphere eventually gets subducted beneath the continents by the time it is 200 million years old.
Three types of ion configurations
Tetragonal, octahedral, and cubic
Why do the minerals in a geode form euhedral crystals rather than anhedral grains?
The crystals have abundant room to grow within a rock cavity.
What is the prime characteristic that geologists use to separate minerals into classes?
Chemical composition - specifically, the anions in the chemical formula
Outer atoms in a silica-oxygen tetrahedron
4 oxygen
Inner atom in a silica-oxygen tetrahedron
silicon
the silica-oxygen tetrahedra is the building block of which chemical class of minerals?
Silicates
Which of the following classes of minerals are most abundant in the Earth's crust and mantle?
silicates; 95%
Adjectives for mineral luster
earthy, glassy, metallic
The hardness of a mineral is determined by
its ability to resist being scratched by other substances; Mohs hardness scale
Obsidian is a volcanic glass that forms when lava cools very quickly and consists of a solid mass of glass through and through. Why is obsidian not classified as a mineral?
The atoms or molecules in obsidian do not have a crystalline structure.
The smallest structural unit describing the repeating pattern in a minerals crystal structure is the unit cell. Is the following true or false? The chemical formula for the unit cell is the same as that of the mineral.
False
The structural arrangement of atoms in the crystal lattice of a mineral is most strongly determine by
the size of anions
Isomorphic minerals share which of the same properties
crystal structure
Compounds with the same chemical formula are always the same mineral
False
Of the bonds we talked about, the strongest in minerals is the
Covalent
Compounds made up of 2 nonmetals from which kind of bond?
covalent
Olivine, a high temperature mineral, is highly susceptible to weathering because
individual covalently bonded silicate structures are linked via weak, ionic bonds with metal ions
According to the periodic table, an element has the following electron shell configuration: {2, 8, 7}. Which type of bond is it most likely to form with a nonmetal?
covalent
Bowen's reaction series describes
the relationship between mineral crystallization from a melt and temperature and composition
The presence or absence of cleavage in a mineral indicates
whether there are planes through the crystal structure with relatively sparse and/or weak atomic bonds
What composition of magma is produced by melting at lower temperatures?
felsic and intermediate
What composition of magma is produced by melting at higher temperatures?
mafic and ultra-mafic
What happens when a rock moves up in the Earth?
It is subjected to slightly lower temperatures and much lower pressures, and it begins to melt.
Identify the factors that cause melting and thus the formation of magma.
addition of volatiles, heat transfer, and decompression
1st step in fractional crystallization
magma, after entering through the bottom of the magma chamber, reaches the top of the chamber
2nd step in fractional crystallization
magnesium- and iron-rich minerals begin to crystallize
3rd step in fractional crystallization
Mineral crystals, having a higher density than liquid magma, sink to the bottom of the magma chamber
4th step in fractional crystallization
The magma shifts toward a more intermediate composition
What does grain size generally indicate about the cooling of a melt?
larger crystals indicate the melt cooled gradually
Which factors control the cooling time of magma within the crust?
the volume of the intruded magma and the depth at which the magma cools
intrusive igneous rock
igneous rock that formed below Earth's surface
extrusive igneous rock
Rock that forms when magma cools above the surface of Earth
Four tectonic settings of igneous activity
continental rift, hot-spot volcano, mid-ocean ridge, and subduction zone
Pluton creates what kind of texture of igneous rock?
Crystalline texture
Explosive eruption creates what kind of texture of igneous rock?
Fragmental texture
Lava flow creates what kind of texture of igneous rock?
Glassy texture
The image shows Mount St. Helens two years after its 1980 eruption. Given the shape of the volcano and presence of a lava dome (source of the steam), what is the most likely composition of the associated magma?
felsic to intermediate
An explosive volcanic eruption does not produce lava flows because
the sudden release of accumulated gas pressure blasts the lava upwards, forming pyroclastic debris
Viscosity
A liquid's resistance to flowing
Scientists estimate the recurrence interval of eruptions at Yellowstone caldera is about 730,000 years. Which of the following statements best describes the recurrence interval of Yellowstone caldera?
Yellowstone erupts on average about every 730,000 years, but it may erupt sooner or later than that.
How can you tell when polarity reverses or moves?
Based on the polarity of old rocks; once rocks cool below the curie temperature, their polarity is locked in and can't change, making it relatively easy to connect the dots on when the magnetic field flipped or the poles moved.
Alfred Wegner is best remembered for
being the first to put together a hypothesis for continental drift based on a variety of scientific data sources
Which part of the earth do geophysicists think generates its magnetic field? The earth's:
core
3. Which statement about magnetic reversals is correct?
Reversals are random; we cannot predict when the next reversal will occur.
Magnetic declination refers to:
the angular difference between a compass reading at a certain location and the direction of the True, or Geographic North Pole
Why can the earth's inner core not act as a permanent magnet?
Its temperature is far hotter than the Curie temperature for any magnetic material
If a flow of basalt were to cool and crystallize at the magnetic South Pole, what would be the orientation of its locked-in magnetic lines of force?
vertical to the earth's surface;
The geodynamo generates electric currents within the liquid outer core that are responsible for:
generating most of the earth's magnetic field;
Over the past 30 thousand years, what has been the relationship between the North magnetic pole and North geographic (rotational) pole?
Although the geographic pole is constantly moving in random directions, it always stays near to the magnetic pole.
Which one of the following is not a piece of evidence used by Wegner to argue for continental drift?
magnetic reversals in ocean floor basalts show a mirror image across mid ocean ridges
the difference between a theory and a hypothesis is
a theory is well tested
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