Chapter 21 Conceptual Physical Science (Plate Tectonics and Earth's Interior)
Each step of 1 on the Richter scale corresponds to a change in energy release of
30.
Volcanoes do not form at which type of convergent plate boundary?
Continental-continental convergent boundaries.
The Himalayan Mountains formed at which type of plate boundary?
Continental-continental convergent boundary.
If seafloor spreading creates new lithosphere, does the size of the Earth change?
No, older crust is recycled back into the asthenosphere.
Which seismic waves produce a wave shadow?
P- and S- waves
Which of the following did Alfred Wegener NOT use to support his theory of continental drift?
Peleomagnetic data.
Why is it so important to survey the ocean floors?
To know topography and possible hiding places for submarines.
Where does a tsunami usually occur?
Underwater reverse fault.
Granite does not readily form near oceanic-oceanic convergent boundaries because
all of the above. (The magma formed at this type of boundary is not conductive to producing granitic type rocks. Granite forms from granitic magma and most oceanic materials is basaltic in origin. Oceanic-Oceanic convergence often results in the eruption of andesitic lavas.)
Magnetic surveys of the ocean floors reveal
alternating stripes of normal and reversed polarity paralleling the mid-ocean ridge.
Earth's core is probably composed of
an iron-nickle alloy.
Earthquake P-waves
are longitudinal vibrations similar to sound waves.
The theory of continental drift is supported by paleoclimatic data, the jig-saw fit of the continents
at their continental margins, and paleontology.
At divergent boundaries the dominate rock type is
basalt.
The ocean crust
becomes progressively older away from the mid-ocean ridge.
Compressive forces cause the crust to
buckle and fold, thereby shortening the crustal surface.
In a folded sequence of rocks we find younger rocks at the axis of the fold and older rocks away from the fold axis. The fold is
called a syncline.
In comparison to P-waves, S-waves
can travel only through solids - not in fluids.
Earth's magnetic field is not stable; throughout geological time it has changed direction. This change is attributed to
changes in the direction of fluid flow in the molten outer core of Earth.
Reverse fault are the result of
compression.
Isostasy is
crustal equilibrium relative to the mantle.
Divergent boundaries are areas of
crustal formation.
Volcanic activity is associated with
divergent and convergent boundaries.
Two boundaries associated with seafloor spreading centers are
divergent boundaries and transform fault boundaries.
Earthquake activity is associated with
divergent, convergent, and transform plate boundaries.
An anticline is a fold in which the limbs bend
downward.
The lithosphere rides on top of the asthenosphere. Lithosphere movement causes
earthquakes, volcanic activity, and mountain building activity.
In the 1950s a plot of the position of the magnetic north pole through time revealed that
either the magnetic poles had migrated through time or the continents had moved.
Detailed mapping of the ocean floors revealed
huge mountains ranges on the ocean floor, and deep trenches near some of the continents.
Continental crust is
less dense than oceanic crust.
Motion in a P-wave is
longitudinal.
The Richter scale measures an earthquake's
magnitude.
According to the theory of seafloor spreading, molten rock is rising up along
mid-ocean ridges.
Because S-waves do not travel trough Earth's outer core, scientists inferred that the outer core is
molten liquid.
As hot mantle 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.
A fault in which the footwall has moved down relative to the hanging wall is called a
normal fault.
We can say that the 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 regions of
plate collision, subduction, and mountain building.
Tectonic interaction between plate boundaries does NOT explain
polar wandering.
When rock is subjected to compressive force, it may fault. If rocks in the hanging wall are pushed up over rocks in the footwall, it is called a
reverse fault.
The Mohorovicic discontinuity was discovered by observing
seismograms of an earthquake.
Subduction occurs as a result of
slab pull-gravity pulls older and denser lithosphere downward.
The San Andreas fault
stretches from the Gulf of California to Cape Mendocino, California, and separates the Pacific Plate from the North American Plate.
The dominant force at divergent boundaries is
tension.
The theory of continental drift is supported by paleoclimate data, paleontology, and
the jig-saw fit of the continents at their continental margins.
The theory of plate tectonics states that
the lithosphere is broken up into several plates that move about as a result of convective motion in the asthenosphere.
The speed of a seismic wave depends on
the type of material it travels through.
Oceans are about four times as deep as mountains are high. At the bottom pf the ocean are
towering mountains, deep valleys, and deep trenches near the continental borders.
The outer core is thought to molten because it
will not transmit S-waves.
