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