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