PHYSICAL SCIENCE CHAPTER 21
The theory of continental drift is attributed to
Alfred Wegener.
Compressive forces cause the crust to
Compressive forces cause the crust to
The S-wave shadow is a region where _______.
Earth's liquid outer core does not transmit S-waves
The theory of seafloor spreading is attributed to
Harry Hess.
If seafloor spreading creates new lithosphere, does the size of Earth change?
No, older crust is recycled back into the asthenosphere.
The primary evidence that the outer core is molten is an abrupt
The primary evidence that the outer core is molten is an abrupt
Why was it so important to survey the ocean floors?
To know the topography and possible hiding places for submarines.
If the path of polar wandering found from two continents are not the same, then we can say that
at least one of the continents has moved.
In an undeformed sequence of rocks, the youngest rocks are found
at the top of the rock sequence
At divergent boundaries the dominant rock type is
basalt.
The main types of seismic waves are _______.
body waves (P- and S-waves) and surface waves (Love and Rayleigh waves)
When stress exceeds a rock's elastic limit, the rock
can lose its original form and either break or flow.
In comparison to S-waves, P-waves
can travel through solid granite, magma, water and/or air.
Earth's magnetic field is not stable; throughout geologic time it has changed direction. This change is attributed to
changes in the direction of fluid flow in the molten outer core of Earth.
The Earth's lithosphere
consists of the crust and the uppermost part of the mantle.
Magma is generated at all of these plate boundaries EXCEPT: oceanic-oceanic convergent boundaries. continental-continental convergent boundaries. divergent boundaries. oceanic-continental convergent boundaries.
continental-continental convergent boundaries.
Volcanoes do not form at which type of convergent plate boundary?
continental—continental convergent boundaries
Lithospheric plates move in response to
convection cells generated by gravity and heat flow in the mantle.
The lithosphere rides on top of the asthenosphere. Lithospheric movement causes
earthquakes, volcanic activity, and mountain building activity.
An Earthquake occurs as
energy released from Earth's interior travels in the form of seismic waves to Earth's surface.
Earth's internal layers were discovered by studying the movement of P- and S- waves through Earth's interior. In comparison to S-waves, the movement of P-waves is
fast, compressing and expanding the rock as they move through it.
The Earth's magnetic field is attributed to the
flow of molten fluid in Earth's outer core.
Seafloor spreading provided the mechanism for continental drift because at the spreading center _______.
formation of new lithosphere pushes the continents
The hypothesis of continental drift was supported by the jigsaw fit of the continents, similar _______.
fossils, matching rock types, and ancient ice sheets
Granite does not readily form near oceanic-oceanic convergent boundaries because
granite forms from granitic magma and most oceanic material is basaltic in origin, the magma formed at this type of boundary is not conducive to producing granitic type rocks, oceanic-oceanic convergence often results in the eruption of andesitic lavas, (all of the above)
Convection in Earth's mantle is attributed to
gravity and heat flow.
A tsunami is unlike most other water waves mainly because it
has a very long wavelength.
The ultimate cause for tectonic plate movement is _______.
heat transfer away from Earth's interior, and gravity
Detailed mapping of the ocean floors revealed
huge mountain ranges on the ocean floor, and deep trenches near some of the continents
Continental crust extends farther down into the mantle than oceanic crust because
it is thicker than oceanic crust.
The majority of earthquakes occur where
lithospheric plates meet
Paleomagnetism from a rock gives information on the
magnetic field at the time the rock was formed.
Alfred Wegener supported his theory of continental drift by
making a connection between rocks, rock structures, and plant and animal fossils found in both Africa and South America.
The Earth's layer with plastic-like behavior is the
mantle.
The asthenosphere is part of the
mantle.
As hot mantle rock rises, it expands. As it expands it cools. This cooler rock is
more dense so it sinks. This contributes to the heat flow convection process.
Mountains tend to form in long narrow ranges because
of plate convergence—plates coming together.
The theory of seafloor spreading is supported by
paleomagnetic analysis of the ocean's floor.
Which of the following did Alfred Wegener not use to support his theory of continental drift?
paleomagnetic data
We can say that Earth's crust floats on the mantle because
part of the mantle is hot enough to flow as a plastic solid.
Most of Earth's seismic activity, volcanism, and mountain building occur along
plate boundaries.
Convergent boundaries are areas of
plate collision.
Tectonic interaction between plate boundaries does NOT explain
polar wandering.
Earth's internal layers were discovered by studying
seismic waves.
In a compressional fault, the land surface can be _______.
shortened as the hanging wall is pushed upward relative to the footwall
Subduction occurs as a result of
slab pull—gravity pulls older and denser lithosphere downward.
Earth's internal layers were discovered by studying the propagation of P- and S- waves through Earth's interior. In comparison to P-waves, the movement of S-waves are
slower and they can only travel through solids, not liquids.
Earth's internal layers were discovered by _______.
studying the changes in seismic wave velocities
The process in which one plate bends and descends beneath another plate is called
subduction.
Plate tectonics states that
tectonic plates are in slow, but constant motion.
According to the theory of seafloor spreading, molten rock is rising up along
the mid-ocean ridges.
Evidence to support that the inner core is solid and the outer core is liquid comes from
the wave shadow effect of P- and S-waves, and the increase in velocity of P-waves as they encounter the solid inner core.
The theory of plate tectonics states that the continents move because _______.
they are embedded within the drifting lithospheric plates
Oceans are about four times as deep as mountains are high. At the bottom of the ocean are
towering mountains, deep valleys, and deep trenches near the continental borders.
Both earthquakes and volcanic activity are common at the following plate boundaries with the exception of _______.
transform plate boundaries
The shaking during an earthquake can be amplified when the underlying surface is composed of _______.
unconsolidated sediments or artificial fill
Where does a tsunami usually occur?
underwater reverse fault
The thickness of Earth's crust
varies from 10 km under the oceans to 60 km under the continents.
Wegener's theory of continental drift
was not accepted by the scientific community of the early 1900s.
