Geology Exam 2

Front 1

Which of the following is most permeable?

Back 1

gravel

Front 2

What conditions are needed for the development of karst topography?

Back 2

humid climate and carbonate bedrock at a shallow depth

Front 3

Rocks such as limestone, granite, and gneiss cannot be groundwater reservoirs.

Back 3

False

Front 4

Subsidence can occur as the result of extraction of oil.

Back 4

True

Front 5

How can limestone be dissolved by groundwater when it is almost insoluble in pure water?

Back 5

Most groundwater naturally contains some carbonic acid and is slightly acidic.

Front 6

What is karst topography?

Back 6

The topography of regions underlain by limestone and having numerous rounded surface depressions and caves formed by groundwater erosion.

Front 7

The percentage of open space within a rock or sediment is known as its

Back 7

porosity

Front 8

A place where groundwater flows/seeps out of the ground is a(n) ____________________.

Back 8

spring

Front 9

What do the solid particles of a stream include?

Back 9

suspended load and solution load

Front 10

Streams do most of their erosion, transportation of sediment, and deposition of sediment during ____.

Back 10

flooding

Front 11

The average channel velocity increases downstream where the gradient is lower.

Back 11

true

Front 12

Mass wasting can be an important source of sediment carried in a stream.

Back 12

true

Front 13

Describe the hydrologic cycle.

Back 13

Water is evaporated from the ocean, lakes, and streams and becomes water vapor in the atmosphere. Then it precipitates and ends up back on land. On land it may end up in glaciers, in the oceans, in lakes or streams, or it may spend a long period of time underground as groundwater. Water also works its way through plants by evaporation and through animals, where it is used for many processes.

Front 14

Describe where flow velocity is highest in a semi-straight channel. Why is this the case?

Back 14

Flow velocity is highest in the center of the channel, just below the surface, where there is little friction. At the bottom and sides of the channel, the roughness of the channel bed, due to sediments, slows the water down. There is even some frictional resistance where the water meets the air.

Front 15

Distinguish sheet flow from channel flow.

Back 15

With sheet flow, water moves in a more-or-less continuous film over the surface. With channel flow, the runoff is confined to long, trough-like depressions.

Front 16

How is the gradient of a stream calculated?

Back 16

Stream gradient is calculated by dividing the difference between the highest and lowest elevations by the horizontal distance over which the stream flows.

Front 17

The outer bank of a meander in a meandering stream is called the ____________________ ____________________, where (erosion, deposition) ____________________ takes place. The deposit on the opposite side of the channel is called the ____________________, which is where (erosion, deposition) ____________________ occurs.

Back 17

cut bank, erosion, point bar, deposition

Front 18

The types of marine deltas that are recognized, based on the relative importance of the processes involved in their formation are ____________________-dominated, ____________________-dominated, and ____________________-dominated.

Back 18

stream, wave, tide

Front 19

Where are continental glaciers presently found?

Back 19

Greenland and Antarctica

Front 20

In a cross-section of a glacier, where do the greatest flow velocities occur?

Back 20

in the few tens of meters below the surface

Front 21

Glaciers are geologically important because they erode, transport, and deposit so much material.

Back 21

true

Front 22

Basal slip becomes a more important means of glacier movement in warmer months when more meltwater collects at a glacier's base.

Back 22

true

Front 23

How does the water bound in glaciers eventually re-enter the hydrologic cycle?

Back 23

by calving and melt water runoff

At high latitudes glaciers can flow directly into the ocean where they melt or create icebergs that break off and eventually melt back into the ocean water. At lower latitudes or areas remote from oceans glaciers flow to lower elevations where they melt and the water flows into the ground water or returns to the seas by surface runoff. In addition to melting glaciers lose water by sublimation as well.

Front 24

Name some erosional landforms that might help you recognize that a valley had previously been occupied by a valley glacier.

Back 24

U-shaped valley trough, truncated spurs, fiords, hanging valleys, cirques, tarns, arêtes, horns

Front 25

Finely laminated, alternating light and dark layers of sediment deposited in a glacial lake are known as glacial ____________________.

Back 25

varves

Front 26

The oceanic ridge system of which the Mid-Atlantic Ridge is a part is at least how long?

Back 26

65,000 km

Front 27

Where are submarine hydrothermal vents primarily found?

Back 27

near spreading ridges

Front 28

What are reefs?

Back 28

mound-like, wave-resistant structures composed of skeletons

Front 29

The continental shelf is always very wide, extending tens to hundreds of kilometers seaward.

Back 29

False

Front 30

Abyssal plains tend to be most common seaward of passive continental margins.

Back 30

True

Front 31

An active margin in the Western Hemisphere is the west coast of South America.

Back 31

True

Front 32

Briefly explain how atoll reefs develop.

Back 32

These reefs form first on the margins of emergent volcanic islands. As the islands sink by moving farther from the hotspot where they originated, and as the crust they are on cools and subsides, the coral reefs grow upward, maintaining a surface just below or at sea level. Meanwhile, the volcano is eroded below sea level, leaving a ring of coral around where it was.

Front 33

What causes submarine hydrothermal vents?

Back 33

Seawater seeps into cracks in the oceanic crust, is heated by hot rock at depth, and rises to the seafloor to be discharged as hot springs.

Front 34

A flat-topped seamount is called a(n) ____________________.

Back 34

guyot

Front 35

The apparent deflection of a moving object from its anticipated course resulting from Earth's rotation is called ____________________ ____________________.

Back 35

Coriolis effect

Front 36

Mass wasting does NOT occur on ____.

Back 36

no where

Front 37

Mass movement that occurs along a curved surface of a rupture is known as ____.

Back 37

slump

Front 38

Some mass wasting occurs at almost imperceptibly slow rates.

Back 38

true

Front 39

A loud thunderclap may be sufficient to trigger a landslide of an unstable slope.

Back 39

true

Front 40

Most large mass movements can be prevented given sufficient study and planning.

Back 40

false

Front 41

How does water content affect mass wasting?

Back 41

It adds weight to the slope material, decreases inter-grain friction, and can lubricate the base of the unstable slope.

Front 42

Briefly explain why a region that is tectonically active may be particularly vulnerable to mass wasting.

Back 42

Such a region is likely to contain faults and highly fractured bedrock, have young steep slopes, and experience many earthquakes.

Front 43

What human activities contribute to or cause mass wasting?

Back 43

Activities such as undercutting slopes (to build roads for example), overloading slopes by construction, adding water, and removing or replacing vegetation.

Front 44

Geologists call the down slope movement of material under the direct influence of gravity ____________________.

Back 44

mass wasting

Front 45

The material accumulated at the base of cliffs where rocks fall is known as ____________________.

Back 45

talus

Front 46

Which of the following is not a factor affecting earthquake intensity?

Back 46

the time elapsed since the last earthquake

Front 47

What does the magnitude of an earthquake measure?

Back 47

the energy released

Front 48

What is the composition of the core?

Back 48

iron and nickel metal

Front 49

The percentage of all earthquakes that occur along a plate boundary is nearly what?

Back 49

95 percent

Front 50

The Modified Mercalli Intensity Scale is a subjective scale to measure the destructive effects of an earthquake.

Back 50

true

Front 51

On the Richter Scale, an earthquake of 6.0 releases ten times as much energy as an earthquake of 5.0.

Back 51

False

Front 52

Explain why the portions of the San Andreas fault that are "locked" are or are not safer than the parts where the two plates slide more or less continually. What is the name of the theory that deals with this issue?

Back 52

The locked portions of a fault are probably less safe than those that slide regularly. The locked portions are storing energy in the surrounding rocks, which will ultimately be released in a large earthquake. The portions that slide frequently build up much less energy since they release it frequently. The name of the theory is seismic gap theory.

Front 53

Almost all intermediate- to deep-focus earthquakes occur along ____________________ plate boundaries.

Back 53

convergent

Front 54

For every integer increase of magnitude on the Richter Scale, ______ times more energy is released by the earthquake.

Back 54

thirty

Front 55

In a reverse fault, the ____.

Back 55

hanging wall goes up relative to the footwall

Front 56

The San Andreas Fault is a ____ fault.

Back 56

strike slip

Front 57

Where is the thickest crust found?

Back 57

beneath mountains

Front 58

Divergent plate boundaries are responsible for most orogenesis.

Back 58

False

Front 59

The Andes formed as result of oceanic-continental convergence.

Back 59

True

Front 60

An important means of continental accretion is plutonism.

Back 60

True

Front 61

Describe the plate tectonics processes and associated stresses that have led to the formation of the Himalayas, the world's largest mountain range?

Back 61

The Indian plate has moved northward into Eurasia, causing compression. First there was subduction of the seafloor that separated the two continents, which formed continental arc volcanoes. Then when the continental plates met, India continued to push into Eurasia. The motions resulted in thrust faulting, reverse faulting, and folding, which thickened the crust to make the mountains.

Front 62

What are the three types of stress?

Back 62

compression, tension, and shear

Front 63

Force applied to a given area is known as ____________________.

Back 63

stress

Front 64

A(n) ____________________ divides a fold into two halves.

Back 64

axial plane

Front 65

Small accreted lithospheric blocks of foreign origin that differ completely from the rocks in surrounding regions are called

Back 65

terranes

Front 66

hazard

Back 66

potentially dangerous event or process

Front 67

risk

Back 67

potential loss of life, property, or production capacity due to a hazard