GEOLOGY NOTE CONEDNCED
Most dry lands lie between ________ degrees north and south of the equator.
20 and 30
What percentage of Earth's total freshwater supply is groundwater?
30.1 percent
What share of Earth's liquid freshwater is groundwater?
96 percent
How might a wildfire influence mass movement?
Because plants on a slope bind the regolith with their roots and shield the soil surface from raindrops, a wildfire that destroys these plants would render the soil looser and more susceptible to the erosional force of rain.
Which of the following is a measure of a stream's ability to transport particles based on size, rather than quantity?
Competence
Which of the following best describes the climatic factors that cause low latitude deserts like the Sahara in Africa?
Cool, dry air aloft is descending; surface winds are blowing toward the equator.
How is a lahar different from a debris flow that might occur in southern California?
Debris flows are composed of soil and regolith, whereas lahars are composed of volcanic materials.
Which of the following factors affect a stream's flow velocity?
Gradient, cross-sectional shape, channel size and roughness, and discharge all affect a stream's flow velocity.
How might a stream channel become braided?
If a large portion of a stream's sediment load consists of coarse material and the stream has a highly variable discharge, a stream channel can become braided.
Which of the following best describes a graded stream?
It is basically in equilibrium, neither eroding nor depositing material
________ refers to the "bouncing" mode of sand transport in a windstorm or stream.
Saltation
Which of the following statements about mass movement is true?
Some mass movements occur with no discernible trigger.
Which one of the following concerning stalactites and stalagmites is NOT true?
Stalagmites form on the floors of caves below the water table.
Why doesn't sea level drop even though oceans have a higher rate of evaporation than precipitation?
Surface water running off into the oceans makes up the difference between evaporation from the oceans and precipitation into the oceans, creating a balance.
Which situations(s) would trigger the formation of incised meanders? Select all that apply.
The base level of a stream drops, causing the stream to begin downcutting. The land on which the stream is flowing uplifts, causing the stream to begin downcutting.
How does wind's suspended load differ from its bed load?
The bed load consists of sand-sized grains that move by saltation, whereas the suspended load consists of fine, silt- or clay-sized particles that can be carried far distances by the wind once they are initially ejected into the air.
What factors led to the massive rockslide at Gros Ventre, Wyoming? Please select all that apply.
The sandstone layer had almost no support at the bottom of the slope, where it had been undercut by the Gros Ventre River. Heavy rains and meltwater seeped through the sandstone and saturated the clay underneath.
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.
Under what circumstances will the front of a glacier advance, retreat, or remain stationary?
The terminus of a glacier advances if there is more accumulation than ablation, retreats if there is more ablation than accumulation, and remains stationary if accumulation is balanced with ablation.
Which of the following is true of earthflows?
They are viscous and move at slower rates than debris flows.
Valleys deeply eroded by alpine glaciers have what characteristic, cross-valley profile?
U-shaped
Which statement best describes the way vegetation affects slope stability?
Vegetation protects against erosion from raindrops and helps bind together soil and regolith
________ does the most erosional work in deserts.
Water
How does water affect mass-movement processes? Please select all that apply.
Water adds weight to the material on a slope. Water fills the pores between sediment, destroying the sediment's overall cohesion. When only enough water is added to make the sediment on a slope slightly damp, the sediment sticks together and resists downward pull.
The water table is ________.
a boundary between saturated rock below and unsaturated rock above
Which depositional feature would you find at the base of a mountain in an arid climate?
alluvial fan
What is an ephemeral stream?
an intermittent stream that carries water only in response to specific episodes of rainfall
Highly impermeable layers such as compacted clay or shale are known as ________.
aquitards
Which mass movement process has the slowest rate of movement?
creep
A drainage pattern that resembles the branching pattern of a deciduous tree is called ________.
dendritic
Which one of the following is the one best measure of the wetness or dryness of a region?
difference between annual precipitation and evaporation potential
Which example best demonstrates groundwater's power as an erosional agent?
dissolution of limestone leading to sinkholes and caverns
The process by which liquid water changes into water vapor is called ________
evaporation
A hydrothermal vent that periodically or occasionally erupts a column of steam and hot water is called a ________.
geyser
A(n) ________ is likely to host a waterfall or steep rapids today.
hanging valley
A ________ forms when stagnant, glacial ice melts after being buried by drift.
kettle
When water moves in nearly straight-line paths parallel to the stream channel, in slow moving streams, this is called ________.
laminar flow
The downslope movement of rock, regolith, and soil is called ________.
mass movement
Which of the following methods of flood control is the cheapest and most effective?
nonstructural floodplain management
Which of the following are considered triggers for mass movement events? Choose all that apply.
oversteepening of the slope oversaturation of the material ground vibrations
A drainage pattern comprised of streams that diverge from a central area like spokes is called ________.
radial
Of the following, which one would most likely be triggered by an earthquake?
rock avalanche
Which of the following sediments are unstable and at a high risk for mass movement?
sediments that are steeper than the angle of repose
What terms are used to describe how material moves during mass movement? Please select all that apply.
slide fall flow
Which type of mass movement involves a downward sliding mass of rock or unconsolidated material moving along a curved surface?
slump
A ________ is the icicle-like speleothem that grows down from the roof of a cavern.
stalactite
A ________ is a semiarid, transitional region.
steppe
Which type of glacial drift is deposited by glacial meltwater?
stratified drift
A stream is said to be a losing stream when ________.
the channel bottom is above the local water table
When rain falls on land, what factors influence the amount of water that soaks in? Select all that apply.
the intensity of rainfall the nature of the surface material the amount of vegetation on the surface the steepness of the slope
What type of material makes up loess deposits?
windblown silt
What are the three main zones of a river system from highest to lowest?
zone of sediment production, zone of transportation, and zone of deposition
