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A disappearing (sinking) creek is ________. |
an influent stream in a karst area |
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A perched water table develops when ________. |
a horizontal aquitard above the regional water table lies below an aquifer |
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A ________ is the icicle-like speleothem that grows down from the roof of a cavern. |
stalactite |
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An aquifer is ________. |
a saturated, porous, and permeable layer or stratum |
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An artesian well is one in which ________. |
water rises above the top of the aquifer without any pumping |
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An unconfined water table is the ________. |
boundary between the aerated zone above and saturated zone below |
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Excessive groundwater withdrawals can cause ________. |
the water table to drop or decline in elevation |
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For unconfined aquifers, what hydrologic factor is approximated by the slope of the water table? |
hydraulic gradient |
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The Unsaturated zone ________. |
lies above the water table |
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The hot spring deposits at Mammoth Hot Springs, Yellowstone National Park, are travertine. What rock probably lies somewhere beneath the hot springs? |
limestone |
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The water table is ________. |
boundary between saturated rock below and unsaturated rock above |
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What force pushes groundwater from pore to pore below the water table? |
pressure gradient or hydraulic gradient |
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Which common, rock-forming mineral or mineral group is most readily dissolved by groundwater? |
Calcite |
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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. |
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Which of the following describes the configuration of an unconfined water table around a pumping well? |
cone of depression |
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Which one of the following concerning artesian wells is not true? |
When the well penetrates the aquifer, the water rises to the bottom of the aquitard above the aquifer. |
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Which one of the following concerning stalactites and stalagmites is not true? |
Stalagmites form on the floors of caves below the water table. |
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Which one of the following statements is true for an artesian aquifer? |
The water table in the recharge area is at a higher elevation than the top of the aquifer in the subsurface. |
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________ account for the largest usage of groundwater in the United States. |
Agriculture and irrigation |
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_______ are characteristics found in all good aquifers. |
High porosity and high permeability |
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________ are specific features of karst topography. |
Streams flowing into depressions and continuing underground |
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________ controls the ease (or difficulty) of groundwater transmission through a porous material. |
Permeability |
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________ is the volume of voids or open space in a rock or unconsolidated material. |
Porosity |
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________ would have the largest capacity to naturally remove sewage pollutants. |
Slightly clayey sand |
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Artesian groundwater conditions can develop in an inclined aquifer with aquitards above and below. |
True |
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In areas underlain by unconsolidated or weakly consolidated strata, lowering of the water table can cause the land to subside. |
True |
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In general, contaminated groundwater will be naturally cleaned faster by circulation through porous and permeable sands than by circulation through fractured, crystalline igneous and metamorphic rocks. |
True |
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In humid areas and for unconfined, groundwater conditions, the water table generally slopes toward the valley of a perennial stream. |
True |
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The water table is a surface separating the saturated and unsaturated zones. |
True |
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Water-saturated muds have low permeabilities but can have greater porosities than well-cemented sandstone. |
True |
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