Q&A Hero

Q: An alluvial fan ________. A) is another name for a small delta forming along a beach B) a fan-shaped mass of sediment deposited at the base of a mountain front due to an abrupt change in stream gradient C) a fan-shaped sediment mass generated by a distributary channel D) a plant that grows in deltas and is diagnostic of a delta

Q: Which of the following features characterize meandering streams and valleys? A) natural levees; broad floodplains B) rapids; channel bed potholes C) waterfalls; entrenched meanders D) V-shaped valley cross sections

Q: A natural levee is ________. A) an erosional feature B) a depositional feature C) essentially parallel to its stream channel D) both a depositional feature and essentially parallel to its stream channel

Q: 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 ________. A) endotributaries B) exotributaries C) distributaries D) cotributaries

Q: A meandering river is flowing in a broad, alluvial valley and the river is silt-laden but also moves sand and a small amount of gravel. The government decides to build a dam across the valley for power and flood control. What will happen to the river downstream of the dam? A) The river will start to deposit sand and gravel, frequently spilling out of its channel. B) The river will not change. C) The river will respond to the new temporary base level and cut laterally outside its valley, widening the valley. D) The trapping of silt in the reservoir will change the river to a braided stream because it will only have sand and gravel in its sediment load.

Q: Downcutting (also known as rejuvenation) of a stream may be due to ________. A) rising of sea level B) uplift of land C) a decreased gradient D) thermal expansion

Q: Which of the following must result in a lower base level for rivers and streams? A) sea level drops; land subsides B) sea level falls; land rises C) sea level rises; land subsides D) sea level rises; land rises

Q: A river emerges from a valley onto a flat plain, but the river itself lies in a narrow, shallow canyon as it crosses the plain, then plunges into a steep sided canyon as it flow past the plain. A geologist floating down the canyon headed for the whitewater in the canyon notices the river is flowing through lake deposits as it flows across the plain. What happened in this area? A) The river is at base level throughout its trace and has been for a long time. B) The river used to flow into a lake, which formed a temporary base level, but in recent geologic time the lakes dam broke, and the river is now downcutting in response to the change in local base level. C) The river has cut a deep canyon that crossed through a lake, and this process has been continuous for a long time. D) The geologist can't be right; this is an impossible scenario.

Q: Over time as erosion lowers the landscape a river valley will typically ________. A) deepen into a bigger and bigger canyon, like the Grand Canyon B) become steeper and discharge increases in the streams C) become narrower but with a lower gradient, entrenching meanders D) become broader and lower gradient

Q: A river is flowing in a broad, alluvial valley and the river is silt-laden but also moves sand and a small amount of gravel. The government decides to build a dam across the valley for power and flood control. What will happen to the river, upstream of the dam? A) The river will downcut. B) The river will start to deposit sand and gravel, frequently spilling out of its channel. C) The river will not change. D) The river will respond to the new temporary base level and cut laterally outside its valley, widening the valley.

Q: A stream meanders across a broad, flat valley with numerous swamps and lakes. This stream is ________. A) running well above base level B) running at base level or below base level C) running on bedrock D) responding to a fall in base level

Q: When a stream is in a v-shaped valley running on bedrock, the stream is ________. A) well above base level B) at base level C) below base level D) responding to a rise in base level

Q: ________ are characteristics of downcutting streams and a youthful stage of valley evolution. A) Rapids and lots of whitewater B) Wide floodplains C) U-shaped, cross-valley profiles D) Meandering channels and natural levees

Q: 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? A) The natural channel had a lower gradient and less friction than the modified channel. B) The straight channel has a higher gradient and more friction than the natural channel. C) The natural channel had a lower gradient and higher friction than the straight channel. D) All of the above statements are true.

Q: If you just want to go for a swim in a meandering river and want to find a sandy beach, where is the best place to look for your swimming hole? A) a point bar on the inside bend of a meander B) outside bend of the meander loops C) straight stretches between meander loops D) It isn't easy to predict, you'll just have to look around.

Q: People learned by trial and error years ago how to paddle a canoe upstream in meandering rivers, knowing where the strongest currents were located. Assuming you don't want to go backwards, what is the best paddling route to maximize your speed upstream? A) Keep on the outside bends, near the cut banks, as much as possible. B) Stay in midchannel. C) Stay on the inside bend of meanders, crossing over whenever the meander turns so you can stay on the inside bend. D) Always stay close to one bank or the other, regardless of how the river bends.

Q: The Mississippi River today is a classic meandering river. 20,000 years ago the Mississippi River was a major outwash channel for the Laurentide ice sheet, and was characterized by dramatic variations in flow with huge discharge during summer ice melt and a dramatic falloff in discharge during the winter. The river also carried coarser sediment than today, with abundant sand and even gravel in its upper reaches. What does this suggest about the ancient Mississippi? A) It probably looked similar to the river today, but was characterized by more dramatic summer floods that occurred every year. B) It probably resembled modern rivers in Alaska with a broad braided stream valley that dried up during the winter months, producing winter dust storms. C) It was probably a lush heavily vegetated valley due to the nutrients brought down by the glacial meltwater, producing a swampy landscape with numerous channels. D) It is impossible to predict what the river might have looked like.

Q: The Platte River crosses the Nebraska sandhills and carries little silt and clay, but moves large amounts of sand. What kind of stream would you predict from this characteristic? A) meandering stream B) braided stream C) bedrock stream D) none of the above

Q: Assuming rivers of comparable discharge, which type of stream would most likely be crossable by wading rather than having to swim? A) braided stream B) meandering stream C) bedrock stream D) There would be no difference.

Q: You are in a boat and concerned about shallow water in a meandering river. Where should you aim your boat to find the deepest water? A) along the inside of the curve B) midchannel C) on the outside of the curve, close to the cut bank D) It doesn't matter, as long as you remain a meter or two from either bank

Q: ________ is an abandoned, cutoff, meander loop. A) A bulltrail B) An oxbow C) A cowhock D) A gatorback

Q: At a bend in a river, the main erosion is ________. A) on the outside of the bend B) on the inside of the bend C) both outside and inside the bend D) at an oxbow lake

Q: The single most important erosional agent is ________. A) running water B) wind C) ice D) waves

Q: ________ generally constitutes the highest percentage of the annual sediment load moved by a stream. A) Bed load B) Dissolved load C) Suspended load D) Saltation load

Q: The suspended load of a stream ________. A) is deposited before the bed load B) is highly soluble substances C) moves along the bottom D) usually consists of fine particles

Q: ________ describes the total sediment load transported by a stream. A) Capacity B) Discharge C) Competence D) Hydro-load factor

Q: ________ make up the suspended loads of most rivers and streams. A) Dissolved ions and sand B) Dissolved salts C) Silt and clay-sized, detrital grains D) Sand and gravel that move during floods

Q: The type and amount of material carried in the suspended load of a stream depends on ________. A) turbulence and viscosity B) source accessibility and slope C) ground cover and channel shape D) flow velocity and discharge E) settling and flow velocities

Q: The main source of the dissolved load in a stream is ________. A) material along the sides of the stream channel B) material along the bottom of the stream channel C) groundwater D) salt flats E) cut bank soil

Q: The main power of water in a channel is related to its ________. A) velocity and temperature B) viscosity and velocity C) discharge and viscosity D) slope and discharge E) slope and temperature

Q: As stream discharge increases ________. A) velocity, width, and depth increase B) only velocity increases C) velocity, width, and depth decrease D) only depth increases

Q: If you were to examine the profile of a typical river, you would probably find that the gradient is ________. A) steepest near the mouth B) steepest near the head C) the same at both the head and mouth D) none of these

Q: As a stream changes from its headwaters to its mouth, which of the following is not likely to occur? A) Flow velocity decreases. B) The channel gets wider downstream. C) Sediment size gets smaller downstream. D) The channel gets smoother. E) The volume of water increases.

Q: The Mississippi River has an average discharge of 17,300 cubic meters per second but the ________ River discharges 12 times more water than the Mississippi River. A) Colorado B) Nile C) Yangtze D) Amazon E) Yukon

Q: A stream begins at an elevation of 200 meters and flows a distance of 400 kilometers to the ocean. What is the average gradient? A) 2 m/km B) 2 km/m C) 0.5 m/km D) 0.5 km/in

Q: Which of the following is the correct definition of stream gradient? A) the distance traveled by water in a channel times a drop in elevation B) the drop in elevation of a stream divided by the distance the water travels C) the water pressure at the bottom of the stream divided by the stream's width D) the increase in discharge of a stream per unit drop in elevation

Q: Which of the following is not a factor influencing a stream's flow velocity? A) channel slope B) channel sinuosity C) channel roughness D) channel width and cross sectional shape E) the amount of water in the channel

Q: A stream's turbulence is strongly influenced by its ________. A) temperature B) sediment load C) velocity D) viscosity E) sinuosity

Q: Laminar flow, where water moves in approximately straight-line paths, characterizes ________. A) fast-moving streams B) slow-moving streams C) the edges of channels D) the bottoms of channels E) all of the above

Q: The Trellis drainage pattern shown below develops ________. A) in areas of relatively uniform surface materials B) on isolated volcanic cones or domes C) on highly jointed bedrock D) in areas of alternating weak and resistant bedrock E) in areas of folded and fractured domes

Q: A ________ stream pattern is developed only on growing mountains like volcanoes or where the land surface is tectonically doming upward. A) radial B) dendritic C) boreal D) trellis

Q: A dendritic (tree-like) drainage pattern develops in regions where the underlying material is relatively uniform so the major control on the water movement is ________. A) vegetation B) slope C) saturation D) climate E) sediment load

Q: Sediment deposition occurs primarily in what part of a river system? A) the head waters B) the drainage divide C) the trunk stream D) near the outlet E) the flood plain

Q: Sediment is neither stored nor produced ________. It is primarily a zone of transport in a river system. A) in the head waters B) in the drainage divide C) in the trunk stream D) near the outlet E) in the flood plain

Q: Sediment production occurs primarily in ________ part of a river system. A) the head waters B) the drainage divide C) the trunk stream D) the outlet E) the flood plain

Q: Which of the following is not a significant factor in determining whether precipitation will soak into the ground or run off on the surfaces? A) steepness of the slope B) vegetation C) saturation level D) lithology E) amount and duration of precipitation

Q: Which of the following is not part of the water cycle? A) water evaporating from a lake B) water infiltrating into the soil and bedrock C) calcium carbonate dissolving in soil water and groundwater D) water moving into creeks and streams following a rainstorm

Q: Which one of the following statements is correct? A) Sea level drops when water is stored in expanding ice sheets and continental glaciers. B) Sea level rises when water is added to the oceans through increased rainfall and increased inflow from rivers. C) Sea level drops when evaporation rates increase over the oceans and when this extra atmospheric moisture falls on land as rain. D) Sea level rises when water is stored in expanding ice sheets and continental glaciers.

Q: The release of water vapor to the atmosphere by plants is called ________. A) evaporation B) degassing C) transpiration D) infiltration

Q: Water plays an important role in sculpting the landscape of continents because ________. A) water is a major cause of erosion on land B) water contributes to plant and animal life that strongly affects the landscape C) water deposits sediments in areas like the Grand Canyon and Yellowstone National Park where they landscape is changing rapidly D) water moves through streams that are a major cause of mass wasting E) ground water causes sinkholes and domes that change the landscape rapidly

Q: The main process that links water in the atmosphere with water on the Earth's surface is ________. A) transpiration B) infiltration C) evaporation D) condensation E) wind

Q: Approximately how much of the Earth's water supply is saline? A) 20% B) 43% C) 67% D) 98% E) 100%

Q: Most insurance companies will not insure property with a known landslide hazard. Why? A) The risk is negligible on human time spans, but they are unwilling to take the risk because of liability. B) The risk is high on human life time scales, and the hazard is difficult to assess. C) They are known to always occur during major disasters like earthquakes and hurricanes, and they don't want the exposure to a large disaster. D) They are just being cheap.

Q: Most stream valleys have a V shaped cross section because ________. A) water washing down the slope makes straight channels. B) vegetation on the slopes forces this profile. C) mass wasting of weathered rocks on the slope maintain an angle of repose slope. D) none of the above

Q: Which of the following mass movements is most likely to occur in a geologic setting where the rock strata are inclined? A) debris flow B) slump C) creep D) rockslide

Q: Consider a weathered rock or soil particle lying on a slope. How will the gravitational force pulling the particle downward along the land surface vary with the inclination of the slope? A) It will increase as the slope angle is lessened. B) It will decrease as the slope angle is lessened. C) It is not affected by the slope angle. D) It will possibly increase or decrease as slope angle is lessened, depending upon other factors.

Q: In terrain with steep hill slopes, which crop and cultivation technique will minimize soil erosion? A) corn; rows trending straight down the slope, frequent cultivation B) apples; land between the trees is planted in grass and not cultivated C) winter wheat; after the harvest, the field is plowed and left idle until next fall D) bean; rows are spaced wider than on a level field

Q: In North America "no till farming" has become a widespread practice made possible by genetically modified (GM) crops that can be sprayed with herbicide that kills everything but the GM plant. Evaluate the following statements on the role of GM crops on soil conservation issues? A) They are a disaster. By killing all plants except the GM organism they expose the soil to increased erosion. B) They have no effect one way or the other on soil erosion. C) The no till practice dramatically improves soil conservation by providing loose organic matter cover to the soil surface, breaking up wind and runoff, lowering erosion rates. D) The herbicides kill beneficial plants and animals and eventually will make the soil sterile.

Q: Climate change and human activity like overgrazing of grasslands is leading to large areas subject to "desertification" where native grass cover dies out during drought periods, exposing soil to erosion. What is potentially the greatest initial soil erosion potential during this type of an event? A) loss of topsoil by wind erosion on a large scale B) local gullying produced by intermittent rain storms C) sand blown in from adjacent deserts D) growth of shrubs shading the ground, further killing the grasses

Q: After the drought of the 1930's farmers in the Great Plains were encouraged to plant rows of trees across fields to decrease soil erosion. How would this reduce soil erosion? A) Tree roots would retard runoff and prevent erosion. B) The trees can serve as windbreaks to slow wind erosion. C) The trees helped shade the ground, retaining moisture. D) The trees had no effect; they were just used to improve the land appearance after the great depression.

Q: Water runoff is a major factor in soil erosion, what is a common land use practice on slopes to minimize soil erosion? A) planting trees B) adding a rock mulch layer to slow water runoff C) planting row crops with rows running downhill, to minimize channelization of flow D) terracing slopes to stop downslope runoff and rill formation

Q: As an erosional process, how is mass wasting unique compared to wind, water, and ice? A) Mass wasting affects particles of all sizes whereas the others affect only smaller particles. B) Mass wasting does not require a transporting medium. C) Mass wasting affects much larger geographic areas than does wind, water, and ice. D) All of the above make mass wasting unique compared to wind, water, and ice.

Q: Deforestation of rain forests exposes tropical soils that are famous for their low fertility, despite the fact that they had previously hosted a lush tropical forest. Which soil type would describe these soils? A) Andisolsyoung soils formed on volcanic ash and volcanogenic sediment B) VertisolsSoils containing large amounts of clay, which shrink upon drying and swell with the addition of water. Found in subhumid to arid climates C) HistosolsOrganic soils with little or no climatic implications. Can be found in any climate where organic debris can accumulate to form a bog soil. Dark, partially decomposed organic material commonly referred to as peat D) OxisolsSoils that occur on old land surfaces unless parent materials were strongly weathered before they were deposited. Rich in iron and aluminum oxides, Oxisols are heavily leached, hence are poor soils for agricultural activity

Q: Soil classifications, like biological classifications, use a taxonomy. The first syllable(s) gives a descriptive term and last syllable is ________. A) sol B) soil C) solt D) drt

Q: Which soil horizon represents the uppermost limit of the zone of accumulation, also referred to as the subsoil? A) A B) B C) C D) E

Q: Digging downward through a soil profile, how deep would you have to go before you found recognizable fragments of the parent rock for the soil? A) A B) B C) C D) E

Q: The word topsoil is commonly used, but not always correctly. The proper definition is ________. A) the A, E and B horizons B) the dark, organic rich layers of O and A C) the entire soil down to the base of the C horizon D) only the O horizon

Q: From the land surface downward to the unweathered bedrock, which of the following is the correct order of the different soil horizons? A) 0, A, E, B, C, bedrock B) A, B, C, D, E, bedrock C) E, A, B, C, 0, bedrock D) D, E, C, B, A, bedrock

Q: Which of the following best describes the process of eluviation? A) removal of very fine-sized silt and clay particles from the A and E soil horizons B) buildup of calcite in the B-horizon of pedocal soils C) removal of soluble chemical constituents from the A and B soil horizons D) feldspar decomposition and leaching of the soluble products from the C soil horizon

Q: Which of the following best describe the E soil horizon? A) regolith zone B) erosion zone C) residual zone D) leaching zone

Q: In much of what is now Canada, glaciers covered the land as little as 12,000 years ago and glacial erosion scoured the land surface leaving very thin soil or bare rock over large areas. The Midwestern United States was also covered in ice at this time, yet this area contains some of the richest farm land in the world with thick soils. These soils are formed on glacial sediments and windblown dust deposits from the ice age. Why are the soil conditions between these areas so different when the soils are virtually identical in age? A) It is much colder in Canada so chemical weather is much slower; thus and soils have not had time to form. B) The Midwestern soils are transported soils with soil development on materials that were already loose, unconsolidated materials. C) Sea level rose following the ice age and covered the Midwest with an inland sea, rapidly forming soil. D) The Midwestern U.S. is much flatter than Canada, allowing soils to develop more quickly.

Q: In the Rocky Mountain region of the United States, north-facing slopes (downhill direction is toward the north) are typically moister and more heavily forested than south-facing slopes. Why? A) North-facing slopes receive more sunlight in the summer; snow melts faster and more soil moisture is available for the trees. B) South-facing slopes receive more moisture and sunlight; rock weathering is slower. C) North-facing slopes receive about the same amount of precipitation as south-facing slopes; less moisture evaporates from north-facing slopes. D) South-facing slopes receive less moisture, yet rock weathering is faster.

Q: Organisms contribute to soils formation by ________. A) contributing organic matter to the soil B) degrading organic matter to form humus C) stirring the soil to allow air infiltration D) all of the above

Q: Which type of soil would typically be the richest soil? A) transported B) residual C) upland slope D) desert

Q: Given enough time, what factor is typically most important in soil formation? A) bedrock type B) slope direction C) climate D) months of snow cover

Q: Which term describes a soil formed by weathering of the underlying bedrock? A) transformational B) residual C) relict D) transported

Q: Engineers refer to any loose material on the surface of the Earth as soil. How does this differ from the definition used in Earth sciences? A) There is no difference, the definition is the same. B) Earth scientists use the term soil only for the organic part of the surface materials. C) Earth scientists only use the word soil to refer to the inorganic part of weathered, surface materials. D) An engineer's "soil" is equivalent to what Earth scientists call regolith; soil has a more specific meaning.

Q: A soil that has nearly equal amounts of clay, silt and sand is called ________. A) loam B) lane C) clayey D) rich

Q: Features like rock ledges in badlands or rock fins standing above adjacent valleys are all examples of ________. A) glacial erosion B) river erosion C) differential weathering D) chemical weathering

Q: Deep soils are characteristic of tropical regions whereas thin rocky soils are characteristic of high latitudes. This is a natural demonstration that ________. A) chemical wreathing rates are much higher in the tropics than high latitudes B) physical weathering and erosion rates are higher at high latitude, removing soil faster than it can form C) all of the high latitude regions lost their soil in recent times D) humans living at high latitudes have destroyed the soils by bad farming practices