Geology Test 1
terrestrial planets are mainly composed of _____ while Jovian planets are made dominantly of ____
rock and metals; volatiles
the rate of seafloor spreading exactly matches the rate of
subduction
what would happen if the rate of seafloor spreading was faster than the rate of subduction
the Earth would grow larger
younger oceanic crust will have ____ ocean sediments, while older oceanic crust will have ____ oceanic
thinner; thicker
Wegener's theory of continental drift proposed that the continents plowed through oceanic crust
true
as a descending plate reaches depths of 100 to 150 km, magma is generated and moves upward to form volcanic arcs
true
at transform plate boundaries, earthquakes are common but volcanoes are absent
true
beneath a blanket of sediments, oceanic crust is primarily composed of basalt
true
compared to typical oceanic crust, is about the same as the thickness of the mantle
true
continental coastlines that occur along the margin of a tectonic plate are called active continental margins
true
continental crust is less dense than oceanic crust
true
geomagnetic reversals present a source of information on the rate of sea floor spreading
true
hot spots can occur only within continental plates
true
in the heliocentric model, Earth orbits around the sun
true
the Himalayan Mountains were produced by a collision of India with Asia
true
the best estimate of when the Universe formed is 13.8 Ga
true
the current estimate of the age for the Earth is 4.57 Ga
true
the discovery of sea floor spreading finally provided a mechanism for continental drift
true
the distinction between the crust and the mantle is primarily on the basis of a difference in composition
true
the earth consists of shells or spheres composed of materials having different properties
true
the eruption of Mount St. Helens was associated with activity along a convergent plate boundary
true
the portion of a fracture zone between two offsets portions of a ridge crest is called a transform plate
true
the sun was created at the center of the accretionary disk when the temperature become high enough for the fusion to occur
true
which of the following statements about Earth's core is FALSE
by volume, it is the largest compositional layer of Earth
the discovery of the seafloor spreading finally provided a mechanism for
continental drift
slab pull occurs because subducting slabs are
cooler, and therefore less dense, than surrounding asthenosphere
sea-floor spreading
creates new oceanic crust
the lithosphere is composed of the
crust and the uppermost part of the mantle
with increasing distance from a mid-ocean ridge, the age of oceanic crust
increases
at a subduction zone, the down-going (subducting) plate
is always composed of oceanic lithosphere
according to the figure below, marine magnetic anomalies lay roughly _____ to mid-ocean ridges
parallel
continental coastlines that occur within the interior of a tectonic plate are called _____ margins
passive
the theory of ____ states that the lithosphere is broken into a series of plates that move relative to each other
plate tectonics
the apparent tendency of the north (or south) magnetic pole to vary in position over time is termed
polar wander
deformed (bent, stretched, or cracked) lithosphere occurs
primarily on the margins of tectonic plates
marine magnetic anomalies can be used to estimate the
rate of seafloor spreading
the Jovian planets are
Jupiter, Saturn, Uranus, and Neptune
during a journey to the center of the Earth, one would experience temperature
and pressure both increasing
the Earth's magnetic field is a
dipole, such as that produced by a bar magnet
under the theory of plate tectonics, the plates themselves are
discrete pieces of lithosphere at the surface of the solid Earth that move with respect to one another
seafloor spreading occurs at ____ boundaries
divergent
transform boundaries occur most frequently along ____ boundaries in order to break the ____ into segments so as to accommodate motion on a sphere
divergent; mid-ocean ridges
atoms that are heavier than iron are generally produced by
explosions of supernovas
Hawaii is an example of a volcanic island are formed by subduction
false
according to the Expanding Universe theory, our Universe is contracting
false
continental drift is the hypothesis that the sea floor forms at the crest of the mid ocean ridge, then moves horizontally away from the ridge crest
false
our sun belongs to a galaxy known as Andromeda
false
the distribution of volcanoes across the globe provides the primary indicator of boundaries between all tectonic plates
false
the lithosphere lies directly above the crust
false
the mid-ocean ridges are elevated above the surrounding seafloor because the lithosphere is thickest at the ridges so they stand up taller
false
the rate of the sea floor spreading averages about one meter (3 feet) per year
false
the sea floor is older than the Earth
false
the thickness of the crust is about the same as the thickness of the mantle
false
unlike the lithosphere, the atmosphere has a density similar to the sun
false
regions of the sea floor with positive magnetic anomalies were formed during times when Earth's magnetic field
had normal polarity
Wegener's idea of continental drift was rejected by geologists because
he could not conceive of a valid mechanism that would cause continents to shift positions
which of the following was NOT used as evidence for sea floor spreading
jigsaw puzzle fit of the continents
in the geologic past, the polarity of Earth's magnetic field is
known to have experienced numerous reversals, as shown by remnant magnetization of iron-rich minerals in rocks
in Wegener's evidence for continental drift, continents were proposed to fit together, such as the east coast of South America with the
lower west coast of Africa