Quiz 1 Flashcards
Regions of the seafloor with positive magnetic anomalies were formed during times when Earth’s magnetic field ________.
- was exceptionally strong
- was exceptionally weak
- had normal polarity
- had reversed polarity
had normal polarity
The Moho (Mohorovičić discontinuity) represents a seismic velocity/density step within the Earth. Where is this discontinuity and what layers of the Earth’s structure does it separate?
- The Moho separates the crust from the mantle. It is globally present in the outer earth, deepest under high mountains and most shallow at oceanic ridges.
- The Moho exists as a separating layer within the middle regions of the crust of the Earth.
- The Moho is the boundary between the Earth’s mantle and core.
- The Moho represents a mineralogical phase change of minerals with olivine composition to perovskite.
- The Moho boundary separates the lithosphere from the asthenosphere.
The Moho separates the crust from the mantle. It is globally present in the outer earth, deepest under high mountains and most shallow at oceanic ridges
The Sun was created at the center of the accretionary disk when the temperature became high enough for ________ to occur.
- Combustion
- Fission
- Fusion
- Radiation
Fusion
The mid-ocean ridges are elevated above the surrounding seafloor because ________.
- ridge rocks are hot and therefore have relatively low density
- the lithosphere is thickest at the ridges so they stand up taller
- rising ocean currents create a vacuum that pulls ridges up
- ridge rocks are mafic, which are less dense than ultramafic ocean basin rock
ridge rocks are hot and therefore have relatively low density
The current estimate for the age of Earth of 4.567 Ga comes from ________.
- radiometric age dating of meteorites
- the amount of nuclear fuel in the Sun
- radiometric age dating of sedimentary rocks
- the light from distant galaxies
radiometric age dating of meteorites
In general, the mantle is made of the rock ________ and has a(n) ________ composition.
- basalt; mafic
- granite; intermediate
- gabbro; mafic
- peridotite; ultramafic
peridotite; ultramafic
In the whole Earth, the four most common elements (by mass) are oxygen, silicon, magnesium, and ________.
- Zinc
- Iron
- Water
- Copper
- Lead
Iron
Consult the figure below. Hawaii is an example of ________.
- a volcanic island arc formed by subduction
- transform margin
- mid-ocean-ridge volcanism
- hot-spot volcanism
hot-spot volcanism
In the geologic past, the polarity of Earth’s magnetic field is ________.
- unknown, but it is assumed to have been identical to today’s
- known to have stayed constant through time, based on theoretical calculations
- known to have stayed constant through geologic time, as shown by remnant magnetization of iron-rich minerals in rocks
- known to have experienced numerous reversals, as shown by remnant magnetization of iron-rich minerals in rocks
known to have experienced numerous reversals, as shown by remnant magnetization of iron-rich minerals in rocks
If a geologist discovered striations (scratches) on bedrock surfaces and small hills composed of poorly sorted sediment, what could he or she conclude about the area?
- that a fault used to run through the area
- that the area used to be a beach along an ocean
- that glaciers had once covered the area
- that mountains had once covered the area
that glaciers had once covered the area
Which basic type of plate boundary is shown in the image below?
- Transvergent
- Convergent
- Divergent
- Transform
Convergent
Seafloor spreading occurs at ________ boundaries.
- Divergent
- Convergent
- Transform
- Transvergent
Divergent
Which basic type of plate boundary is shown in the image below?
- Convergent
- Transvergent
- Divergent
- Transform
Divergent
T/F: A rock is a solid organic substance in which atoms are arranged either in an orderly pattern (crystalline) or as irregularly shaped grains; a mineral is an aggregate (mixture) of rocks.
False
According to the figure below, marine magnetic anomalies lay roughly ________ to mid-ocean ridges.
- Perpendicular
- At an obtuse angle
- Adjacent
- Parallel
Parallel
