ch. 4 -- geology paper exam
the Wadati-Benioff zone extends down within the mantel to a maximum depth of ____________km
660
_____________ proposed the continental drift hypothesis
Alfred wegener
which the following statements is true concerning rock produced a mid-ocean ridge
basalt is produced at shallow depths and gabbros at deeper depths
deep-oceanic trenches are features of ___________ plate boundaries
convergent
which basic type of plate boundary is shown in the image below
convergent
slab pull occurs because subduction slabs are _____________, and therefore _______________ dense, than surrounding asthenosphere
cooler; more
seafloor spreading
creates new oceanic crust
the lithosphere of the Earth is generally thinnest at ________ plate boundaries
divergent
which basic types of plate boundary is shown in the image below
divergent
continental coastlines that occur within the interior of a tectonic plate are called _______________ margins
passive
hot-spot tracks result from moving
plates
the san Andreas fault zone in California is an example of a _____________ plate boundary
transform
which basic type of plate boundary is shown in the image below
transform
segments of mid-ocean ridge systems are offset. between the offset segments we observe
transform boundaries
the image below shows a cross-sectional view of a typical subduction zone, with earthquake locations shown with small dots. the band of earthquakes that follows the shape of the downing plate is termed the ___________- zone.
wadati-benioff
earthquakes occur most frequently near __________ margins
active
the youngest sea floor if typically found
along mid-ocean ridges
most of the pushing force driving plate motion is produced
at mid-ocean ridges
most of the pulling force driving plate motion is produced
at subduction zones
the image below shows a view of a typical segmented mid-ocean ridge. which letter below marks the location of the active transform fault
b
when two continental plates come together at a convergent boundary, the result is
collision and mountain formation
large, thick-crusted, non volcanic mountain belts, like the Himalayas, are associated with
continent-continent collisions
subduction zones are found at ____________ plate boundaries
convergent
mid-ocean ridges are segmented and contain which two basic types of plate
divergent and transform
seafloor spreading is most likely to occur at
divergent boundaries
the distribution of _____________ across the globe provides the primary indicator of boundaries between all tectonic plates
earthquakes
at transform plate boundaries
earthquakes are common but volcanoes are absent
summed over the entire surface of the Earth, the rate of spreading at divergent boundaries is ____________ lithospheric consumption at subduction zones
equal to
__________________ proposed seafloor spreading
harry hess
hawaii is an example of
hot-spot volcanism
the theory of plate tectonics
incorporates and explained both seafloor spreading and continental drift
with increasing distance from a mid-ocean ride, the age of oceanic crust
increases
unlike the lithosphere, the asthenosphere
is able to flow over long periods of time
at a subduction zone, the downing (subducting) plate
is always composed of oceanic lithosphere
the lithosphere of the Earth will not flow because it
is too cool
how does the lithosphere respond to stress
it bends or breaks
which of the following is true of the lithosphere
it is composed of the crust and the uppermost part of the mantel
the thickness of oceanic lithosphere is
least near the mid-ocean ridges and thickens away from the ridges
compared to typical oceanic lithosphere, the thickness of continental lithosphere is
less
a volcanic island arc forms when
oceanic lithosphere subducts beneath another oceanic lithospheric plate
under the theory of plate tectonics, the plates themselves are
pieces of lithosphere at the surface of the solid Earth that move with respect to one another
mid-ocean ridges are elevated above the surrounding seafloor because
ridge rocks are hot and therefore are relatively less dense than the surrounding seafloor
on either side of a mid-ocean ridge, the lithosphere begins to
sink because it cools and contracts
oceanic lithosphere thickens away from the mid-ocean ridge primarily due to
the addition of new lithospheric mantle as a result of cooling
a triple junction, like the one shown below, is a place on Earth's surface where
the boundaries of three lithospheric plates meet at a single point
hot spots can occur
within either continental or oceanic plates
