Exam #3 - Geology 1403 with Dalman at Blinn College

A graben is an upraised block bounded by two reverse faults. T or F

False

A thrust fault is best described as ______________

A low angle, reverse fault

In thrust faulting, __________________

the crust is shortened and thickened

A(n) ___________________ is a thick accumulation of sediments and small, tectonic blocks formed of material scraped off a descending lithospheric plate

Accretionary-wedge complex

Accentionary wedges develop along subduction zones where sediments and other rocks are scraped off a descending plate and piled against the leading edge of the overriding plate. T or F

True

A good example of present day, passive continental margin is the _______________

east coast of North America

In a reverse fault, the hanging wall block moves up relative to the footwall block. T or F

True

Normal fault form in response to horizontal, tensional stresses that stretch or elongate the rocks. T or F

True

A(n) _____________ fault has little or no vertical movements of the two blocks

Strike-slip

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

San Andreas strike-slip fault

How do freezing, thawing, wetting, and drying contribute to soil creep?

The soil expands and contracts, lifting particles and dropping them a slight distance downslope.

Which of the following statements concerning mudflows is not true?

Mudflows deposit talus slopes.

Which of the following materials has the maximum sustainable slope angle as determined by the angle of repose?

Dry Sand

Where do the most rapid mass-wasting events occur?

Rugged, geologically young mountains

As an erosional process, how is mass wasting different from wind, water, and ice?

Mass wasting does not require a transporting medium; gravity is its controlling force.

Of the following, which one would most likely be triggered by an earthquake?

Rock Avalanche

How do the strength and the cohesion of clay-rich regolith or soil change with the addition of water?

Water reduces the strength and the cohesion.

A triggering mechanism, such as heavy rains or an earthquake, are necessary for mass wasting to occur. T or F

False

Which one of the following does not apply to stream turbulence and average velocity?

Laminar flow, dissolved load

Slump describes the very slow, downhill movement of soil and regolith

False

Consider a steep highway cut made by removing granite bedrock with conditions ranging from slightly weathered to fresh and fractured. Which of the following situations is the most stable against rockslides?

One set of widely spaced, subhorizontal fractures

For the same discharge, gradient, and channel cross section, a stream with a boulder-strewn bed would be more turbulent than one with a sandy bed. T or F

True

________________ are components of the hydrologic cycle that release water vapor directly into the atmosphere?

Evaporation and transpiration

A V-shaped valley and no floodplain indicate a youthful, downcutting stream. T or F

True

A _____________ drainage pattern is common in the Appalachian Valley and Ridge Providence

Trellis

In the absence of cutoff, how does a river meander loop behave over time?

The gradient is lowered as the channel lengthens and migrates towards the cut or outer bank of the loop

A water gap is ________________

A short segment of canyon formed where a river flows across the outcrop area of resistant, ridge-forming rock layer

____________ in a delta are essentially cross strata inclined towards deeper water

Foreset beds

Most precipitation in land areas originates by transpiration and by evaporation from lakes and rivers. T or F

False

Water infiltrates down to the water table from influent streams.

True

Alluvial fans develop at unusual locations where stream gradients abruptly increase for a short distance. T or F

False

Which of the following best describes how geysers erupt?

With a slight reduction in pressure, water in a saturated, natural conduit suddenly boils, sending a plume of steam and hot water into the air above the vent.

A stream is said to be perennial and effluent when ____________.

The local water table is above the channel bottom year round

In humid areas and for unconfined, groundwater conditions, the water table generally slopes toward the valley of a perennial stream. T or F

True

Warm springs in the Eastern United States are mainly heated by geologically young, igneous rocks below the surface. T or F

False

Which of the following is not a general characteristic of groundwater?

Rarely contains dissolved constituents

Speleothems generally form below the water table by water dripping from the roofs of caverns. T or F

False

In areas of karst topography, rare surface streams typically flow into depressions called sinkholes and continue to flow underground for some distance. T or F

True

Which of the following describes the configuration of an unconfined water table around a pumping well?

Cone of depression

___________ are characteristics found in all good aquifers.

High porosity and high permeability

Till is an unsorted sediment deposited directly from the melting glacial ice; stream action is not involved. T or F

True

Which type of glacial drift is deposited by glacial meltwater?

Stratified drift

The Pleistocene epoch of geological time began about 6 million years ago. T or F

False

Surges in glacial movement are probably related to usually fast rates of basal sliding. T or F

True

The ____________ of the geologic time scale represents the time of the most recent Ice Age?

Pleistocene epoch

Melting and evaporation are two forms of ablative calving. T or F

False

Fiords are glacier-cut valleys that flooded as sea level rose in post glacial times. T or F

True

_____________ are erosional features produced by valley/alpine glaciers.

Cirques

Crevasses are short, narrow cracks in the plastic flow zone of a glacier that alternately open and closes as the ice flows along. T or F

False

Which of the following factors did not contribute to climate change?

Changes in solar flares

The Black Hills of South Dakota are a good example of a(n) ________.

dome

Fractures in rock that have not involved any fault slippage are called joints.

True

A good example of a present-day, passive continental margin is the ________.

east coast of North America

The term ________ refers specifically to geologic mountain building.

orogenesis

Which one of the following is an example of an isostatic movement?

uplift of areas recently covered by thick, continental ice sheets

Tensional forces normally cause which one of the following?

normal faults

What caused the mudflows (1985) on the Nevado del Ruiz volcano?

All of these

( Hot ash fell onto snow near the summit.

A crater lake was broken during an eruption.

Warm weather caused rapid melting of snow and ice near the summit)

Solifluction occurs during the warmer summer months.

True

Slump describes the very slow, downhill movement of soil and regolith.

False

Which mass wasting process has the slowest rate of movement?

Creep

Of the following, which one would most likely be triggered by an earthquake?

Rock Avalanche

Solifluction is an important mass wasting process in areas of permafrost.

True

Why is a bird-foot delta like that of the present-day Mississippi below New Orleans likely to change naturally toward one with the shape of an equilateral triangle like the upper-case, Greek letter delta ()?

Potential, new, major distributary channels have steeper gradients than existing channels.

A natural, meandering, river channel is modified into a more or less straight and smooth, canal-like channel. Which of the following statements is correct?

The natural channel had a lower gradient and higher friction than the straight channel.

Alluvium refers to stream deposits, mainly sand and gravel.

True

At the head of a delta, the major channel splits into smaller channels that follow different paths to the sea. These smaller channels are known as ________.

distributaries

________ make up the suspended loads of most rivers and streams.

Silt and clay-sized, detrital grains

________ in a delta are essentially cross strata inclined toward deeper water.

Foreset beds

Which one of the following is not a speleothem?

geyserite

Which of the following best describes how geysers erupt?

With a slight reduction in pressure, water in a saturated, natural conduit suddenly boils, sending a plume of steam and hot water into the air above the vent.

In areas underlain by unconsolidated or weakly consolidated strata, lowering of the water table can cause the land to subside.

True

For unconfined aquifers, what hydrologic factor is approximated by the slope of the water table?

hydraulic gradient

Which of the following statements concerning unconfined aquifers on barrier islands and atolls is correct?

Any salty water in the aquifer will rise if the water table is lowered by pumping.

Which one of the following logically explains why parts of some cavern systems are aerated?

A nearby, downcutting stream lowered the water table after the caves had formed.

Which one of the following samples and experimental measurements would provide the most information about the Earth's climate over the last 100,000 years or so?

cores from the Greenland ice sheet; ratios of the oxygen isotopes (0-18/0-16)

Which one of the following prominent landforms, located from the Wasatch Range, Utah, westward to the Sierra Nevada, California, formed during the Pleistocene glacial episodes?

old shorelines of large, pluvial lakes

A ________ is an erosional feature specifically produced by alpine glaciation.

U-shaped valley

The volume of the Antarctic ice sheet is about equal to the total volume of ice in all alpine glaciers of the world.

False

A(n) ________ is similar in appearance to a sinkhole of a karst area.

Kettle

A cirque represents an erosional feature formed in what was an important accumulation zone for snow and ice at the upstream head of a glacier.

True

Which of these features would NOT commonly be found along a meandering stream? _

Waterfall

In meandering streams, the most erosion occurs at the _____.

cut banks

Which stream drainage pattern is associated with highly faulted or jointed terrain?

rectangular

The sequence of events (from earliest to latest) that created the Incised Meander seen at The Loop, Utah is _____.

Meandering; Uplift of the land (Drop in Base Level); Downcutting

Which channel type indicates lateral erosion is prominent? _____

meandering

Multiple sinkholes may merge together to form a _____

solution valley

In many areas of the U.S., the overuse of groundwater is causing the water table to drop, and in some places it is also causing ground subsidence.

True

Which rock type is commonly associated with Karst topography? _____

Limestone

Which feature is NOT associated with Karst topography?

Black Smokers

_____ is the ability of a rock to transmit fluids, such as water or oil.

Permeability

The Water Table is the top of the _____.

Saturated zone

Which is the greatest geologic hazard risk for Floridians who live on Karst topography? _____

Sinkhole

Groundwater moves_____.

downwards or upwards depending on gravity and pressure.

The greatest amount of unfrozen fresh water on earth is found in _____.

groundwater

Limestone caves are formed by _____.

Acid Dissolution

A mountain river cuts a ______ shaped valley in cross-section, but an Alpine Glacier cuts a ______ shaped valley in cross-section.

V, U

An Arête is _____.

a narrow knife-like ridge between two glacial valleys

A medial moraine is _____.

A moraine in the middle of an alpine glacier

Around the world, most glaciers are melting and sea level is ____.

Rising

Which is NOT an alternate term for an Alpine Glacier? _____

Ice sheets