Geology Unit 3

Which of the following lines of evidence was introduced by Alfred Wegener to support his hypothesis of continental drift?

1) Jig-saw fit of continents 2) Matching mountain belts 3) Paleoclimactic evidence 4) All of the above

On the average, lithospheric plates are ________ thick.

100 km

According to the design of earthquake magnitude scales, approximately how much more energy is released in a 6.5 Richter magnitude earthquake than in one with a magnitude 5.5?

30 times

In the early part of the 20th century, ________ argued forcefully for continental drift.

Alfred Wegener

__________ is the transfer of heat by mass movement or circulation in a substance.

Convection

Why are most of the Earth's earthquakes' foci located fairly close to the surface, and not farther down?

Earthquakes occur in places where rocks are "rigid," giving them an elastic quality. This is not the case deeper in the Earth.

For the following items, choose from one of the following answers: ____the big volcanoes of Hawaii ____large, fairly steep-sided cones composed of lavas and pyroclastic layers ____massive, gently sloping volcanoes built of successive, basaltic lava flows ____the volcanoes of southwestern Alaska and the Aleutian Islands ____small basaltic cones built during one, short, eruptive episode ____series of eruptions that coats large stretches of land or the ocean floor with lava 1.shield volcanoes 2.composite/stratovolcanoes 3.cinder cones 4.flood basalt

For the following items, choose from one of the following answers __1__the big volcanoes of Hawaii __2__large, fairly steep-sided cones composed of lavas and pyroclastic layers __1__massive, gently sloping volcanoes built of successive, basaltic lava flows __2__the volcanoes of southwestern Alaska and the Aleutian Islands __3__small basaltic cones built during one, short, eruptive episode __4__series of eruptions that coats large stretches of land or the ocean floor with lava

What does the hanging wall do in a reverse fault (and in a thrust fault)?

It moves up relative to the footwall.

Where would you expect to find more deep earthquakes?

Japan

Why do magmas rise toward Earth's surface?

Magmas are mainly liquid and contain dissolved fluids such as water; most are less dense than the adjacent solid rock.

The ___________ scale is based on observations of building damage.

Modified Mercalli Intensity

Comparing the different types of volcanoes (e.g., Hawaiian volcanoes and the Mt. St. Helens volcano), why does the difference in the composition of the magma that fed these volcanoes determine the type of volcano?

Mt. St. Helens was explosive because the magma was more viscous (more "sticky") and felsic.

When an earthquake occurs, people nearby often report that the first thing they notice are sharp raps or knocks -- in other words, sudden, abrupt shakes that rattle their surroundings. Those initial, sudden shocks are probably_______.

P-waves

Which type of seismic wave can travel through the core?

P-waves

The former, late Paleozoic super continent is known as ________.

Pangaea

What is the name given by Wegener to the supercontinent he deduced as existing during the Late Paleozoic-Early Mesozoic eras and then rifting apart into the present continents?

Pangaea

The ________ in California is the boundary between the North American and Pacific plates.

San Andreas strike-slip (transform) fault

Why do all magmas create dominantly silicate minerals upon cooling?

Si and O are the most abundant elements in the magma.

An important aspect of seismic waves is that they have different time gaps on seismograms from different locations. Why would a seismogram recorded closer to the epicenter have the P and S wave arrivals closer together than on a seismogram from farther away?

The arrival time of any wave is based upon its speed. P waves are faster, so they "pull away" form S waves with increasing distance from the epicenter.

Volcanic glass and coarse-grained igneous rocks differ by which of the following?

The glass is formed mostly when lava cools at earth's surface too fast for mineral to form whereas phaneritic rocks cool deep beneath the surface slowly enough for crystals to grow to a visible size.

In the diagram below, match the letter of each illustration to the correct type of plate boundary. Write the number in the box. ____transform 1.Figure (a) ____divergent 2.Figure (b) ____convergent 3.Figure (c)

Write the number in the box. __3__transform 1.Figure (a) __1__divergent 2.Figure (b) __2__convergent 3.Figure (c)

Carefully study the seismogram below and note the features labeled A through G. On the blanks provided beside each item below, write the NUMBER of that that corresponds to each item. Write the number in the box. __4__A surface wave 1.G __3__An S-wave 2.D __2__The first S-wave 3.C __1__The first P-wave 4.B B /\ F |\ /\ / \ ______|\|___________| \/ \/\ / \ G D C \/

Write the number in the box. __4__A surface wave__3__An S-wave__2__The first S-wave__1__The first P-wave 1.G2.D3.C4.B

On the blanks provided below, match the specific type of fault that have been labeled. ____Normal fault ____Reverse fault ____Transform fault 1.(a) left slides up; right is sliding down 2.(b)left slides down; right slides up 3.(c) left slides left; right slides right

__1__Normal fault __2__Reverse fault __3__Transform fault 1.(a) 2.(b) 3.(c)

On the blanks provided below, match the specific type of fold that have been labeled. Picture a wave - __a___ _______ / \ b / / \_______/ ____anicline ____syncline 1.(a) 2.(b)

__1__anicline __2__syncline

Pull-apart, rift zones are generally associated with ________.

a divergent plate boundary

In geologic terms, what are the Hawaiian-Emperor chain of islands and underwater seamounts?

a hot spot track

A transform fault is ________.

a strike-slip fault that forms the boundary between tectonic plates

The formation of a resurgent dome indicates that Mt. St. Helens is ______________.

active

For volcanoes formed over an oceanic hot spot, the volcano farthest from the hot spot will generally be: 1)coldest 2)oldest 3)most subsided (contracted due to loss of heat) 4)most eroded 5)all of the above

all of the above

Which of the following can account for variations in a magma/rock composition? 1) crystal settling 2) magma mixing 3) assimilation of "foreign" rocks by the magma 4) a. and c. only 5) All of these.

all of these

Volcanic bombs originate ________.

as erupted magma blobs that partly congeal before falling to the ground

What is the term for a broad, nearly circular downwarp with the youngest rock units exposed in the center?

basin

Which of the following foundation materials is most stable during earthquake shaking?

bedrock

In general, ___________ will be more likely to erupt explosively. 1)a highly viscous magma 2)a relatively low viscosity magma 3)high-silica magma 4)low-silica magma 5)both a. and b. 6)both b. and c. 7)both a. and c.

both b. and c.

Rapid application of stress on a rock may result in _____, while very slow application of stress over a long period of time may result in _____, respectively.

brittle failure, plastic deformation

What does the addition of water to rocks that are already quite tend to cause? (Hint: It is like adding salt to snow.)

cause the rocks to begin melting

Most folds are a result of which type of stress?

compressional

What plate tectonic process creates complex, non-volcanic mountain systems such as the Alps, Appalachians, and Himalayas?

continent-continent convergence

The fact that a rock is permanently folded or bent shows that it behaved as a _____ material.

ductile (plastic)

If pressure is released, which type of deformation will reverse itself?

elastic

When rocks under stress break and shift along the fracture, what is the resulting structure?

fault

Shield volcanoes are __________-topped, with very ___________ sloping sides

flat, gently

The ________ is the point of origination for an earthquake.

focus

When rocks under stress bend instead of break, what is the resulting structure?

fold

A ________ is a defined, recognizable, mappable, rock unit with a known age.

formation

A ____ uses standardized symbols and patterns to represent rock types and geologic structures.

geologic map

Which of the following rocks is likely to have the most quartz within it and how would it form?

granite; intrusive rock that formed from cooling of relatively high silica magma

What type of composition would result in a magma if basaltic and granitic composition magma were mixed completely at a 1 to 3 ratio?

granodioritic

A very long-lived magma source located deep in the mantle is called a ________.

hot spot

Where do the most powerful earthquakes occur?

in subduction zones like the one in the Pacific Northwest

The ________________ is the rigid layer that comprises the tectonic plates and the __________ is the soft, weak layer of the mantle underneath.

lithosphere, asthenosphere

The Hawaiian Islands are thought to have been formed over a

mantle hot spot

Which method gives reliable warning that an earthquake is about to occur?

no method does, even though all have been tried and tested

Oceanic lithosphere is subducted while continental lithosphere is not because

oceanic lithosphere is denser, especially as it gets older, than continental lithosphere is, so the oceanic lithosphere is able to sink into the mantle like a slowly sinking lead weight.

Most of Earth's seismic activity, volcanism, and mountain building occur along____________

plate boundaries

Which one of the following does NOT contribute to Earth's internal heat?

plate tectonics

Which of the following terms describes a fold with a dipping axis?

plunging

A seismic wave may change direction, without bouncing back, when crossing the boundary between two rock types. This phenomenon is called __________.

refraction

What is recorded on newly formed oceanic crust spreading from mid-ocean ridge to create the magnetic "stripes" that form symmetric patterns parallel to the ridges?

reversals of the earth's magnetic field

Which of the following plate tectonic processes will NOT cause a significant amount of melting of rocks inside the Earth?

rise of the asthenosphere beneath a divergent plate boundary ??

What causes a fold to occur in the earth?

rocks under stress undergo plastic strain, bending but not breaking

A fault occurs when

rocks undergo stress that drives them into plastic deformation??

Jointing in rocks is characterized by ________.

roughly parallel fractures separating blocks that show no displacement

Surface waves are ______ than body waves, and _______ responsible for much ground shaking and structural damage during major earthquakes.

slower, are

Deep-focus earthquakes, those between 300 and 700 kilometers below the surface, occur only in association with ________.

subduction zones

In thrust faulting, ________.

the crust is shortened and thickened

On a global basis, most of the world's magma is generated in which part of the Earth?

the upper mantle

In the cores of anticlines in the Yakima Fold Belt of central and south-central Washington State, faults have developed as a result of the compression of the upper crust. Which type of fault?

thrust or reverse

The San Andreas fault is a famous example of which type of fault?

transform

The San Andreas fault zone is a famous example of which type of plate boundary?

transform