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457. general location of most early cities and towns

near streams (USQRG:27,1,1)
458. two solutions of early humans after streams became insufficient for cities’ water needs

bring water through canals and dig wells (USQRG:27,1,1)
459. groundwater

all water contained in spaces within the bedrock and regolith (USQRG:27,1,3)
460. percentage of Earth’s water that is groundwater

less than 1% (USQRG:27,1,3)
461. amount of groundwater on Earth relative to amount of freshwater in lakes and streams

40 times more (USQRG:27,1,3)
462. amount of groundwater on Earth as a fraction of amount of water contained in glaciers and polar ice

1/3 (USQRG:27,1,3)
463. glacier

body of ice wholly or largely on land that shows evidence of flowing under gravity’s influence (USQRG:27,1,3; USQRG:102,1,3)
464. origin of most groundwater

rainfall (USQRG:27,2,1)
465. two ways by which groundwater moves toward the ocean

directly through the ground or by joining streams on the surface (USQRG:27,2,1)
466. scientist who determined groundwater comes from rainfall

Pierre Perrault (USQRG:27,2,2)
467. Pierre Perrault’s occupation

physicist (USQRG:27,2,2)
468. In what century was it established that groundwater comes from rain?

17th century (USQRG:27,2,2)
469. river that Pierre Perrault used to link rainfall and groundwater

Seine (USQRG:27,2,2)
470. factor that needs to be taken into account when comparing amounts of rainfall and stream runoff

evaporation (USQRG:27,2,2)
471. What land area has no water underneath it?

nowhere (USQRG:27,2,3)
472. depth to which most usable groundwater exists

750 meters (USQRG:27,2,3)
473. volume equivalent to that of all groundwater in the first 750 meters of Earth’s crust

a 55‐meter thick layer of water across the entire Earth (USQRG:27,2,3)
474. greatest depth at which an oil drill found water

9.4 kilometers (USQRG:27,2,3)
475. greatest depth at which groundwater has been found

11 kilometers (USQRG:27,2,3)
476. location at which groundwater has been found at its great depth

Kola Peninsula (USQRG:27,2,3)
477. ethnicity of scientists who discovered groundwater at its greatest known depth

Russian (USQRG:27,2,3)
478. first layer of ground passed through when digging a well

moist soil (USQRG:28,1,0)
479. second layer of ground passed through when digging a well

zone of aeration (USQRG:28,1,0)
480. zone of aeration

open space in regolith or bedrock mainly filled with air (USQRG:28,1,0)
481. another name for the zone of aeration

unsaturated zone (USQRG:28,1,0)
482. amount of water saturation present in the zone of aeration

none (USQRG:28,1,0)
483. third layer of ground passed through when digging a well

saturated zone (USQRG:28,1,0)
484. saturated zone

underground area in which all openings are filled with water (USQRG:28,1,0)
485. water table

upper surface of the saturated zone (USQRG:28,1,0)
486. typical orientation of the water table

sloping toward the nearest stream or lake (USQRG:28,1,0)
487. location of the water table in deserts

far underground (USQRG:28,1,0)
488. capillary attraction

adhesive force between a liquid and a solid that causes water to be drawn into small tube‐like openings (USQRG:28,1,1)
489. type of sediment that allows for a fringe on top of the water table

fine‐grained (USQRG:28,1,1)
490. maximum thickness of the fringe on top of the water table

60 centimeters (USQRG:28,1,1)
491. force that draws ink through blowing paper and kerosene through the wick of a lamp

capillary attraction (USQRG:28,2,0)
492. How does the water table appear in humid regions?

as a “subdued imitation of the land surface above it” (USQRG:28,2,1)
493. topographical location with the lowest pressure on the water table

low points, such as valleys (USQRG:28,2,1)
494. type of area to which water in the water table tends to move

low points (USQRG:28,2,1)
495. event that would occur in the water table if all rainfall ceased

flattening of the water table (USQRG:28,2,1)
496. level that the water table would reach if all rainfall ceased

level of the water table in valleys (USQRG:28,2,1)
497. How are changes in the water table manifested above ground during droughts?

drying up of wells (USQRG:28,2,1)
498. How does water seepage into the ground change if all rainfall ceases?

diminishes and then stops altogether (USQRG:28,2,1)
499. fact that scientists can infer from a dried‐up well

water table has dropped to a level below the well (USQRG:28,2,1)
500. three geological features that result from the water table intersecting the land surface

lakes, marshes, and streams (USQRG:28,fig)
501. How is the water table maintained at a normal level?

repeated rainfall (USQRG:28,2,1)
502. substance that forms a layer coinciding with surface soil

moisture (USQRG:28,fig)
503. upper limit that the water table represents

all readily usable groundwater (USQRG:29,1,1)
504. two groups that seek to determine the depth and shape of the water table

groundwater geologists and well drillers (USQRG:29,1,1)
505. hydrologic cycle

continuous process in which water evaporates from oceans, falls to land as rain, enters the groundwater, and re‐enters the ocean (USQRG:29,1,2)
506. two units commonly used to measure groundwater movement

centimeters per day and meters per year (USQRG:29,1,3)
507. reason for the disparity between the speed of rivers and groundwater

unimpeded path of rivers versus constricted passageways of groundwater (USQRG:29,1,3)
508. porosity

percentage of the total volume of a rock consisting of open spaces (USQRG:29,1,4; USQRG:103,2,21)
509. pores

open spaces in a rock (USQRG:29,1,4)
510. factor determining the amount of water a given volume of rock or sediment can contain

porosity (USQRG:29,1,4)
511. three factors that affect sediments’ porosity

size, shape, and compactness of particles (USQRG:29,1,5)
512. maximum porosity of well‐sorted sands and gravels

approximately 20% (USQRG:29,1,5)
513. maximum porosity of clay

approximately 50% (USQRG:29,1,5)
514. three factors affecting sedimentary rocks’ porosity

sorting and arrangement of particles and extent to which its pores are filled with cement (USQRG:29,1,6)
515. general porosity of igneous and metamorphic rocks

low (USQRG:29,1,6)
516. permeability

measure of how easily a solid allows fluids to pass through it (USQRG:29,1,7: USQRG:102,2,16)
517. expected permeability for a rock with very low porosity

low (USQRG:29,1,7)
518. force that exists between a solid surface and a film of water

molecular attraction (USQRG:29,2,0)
519. relationship between amount of cement present and porosity of a rock

more cement lowers porosity (USQRG:29,fig)
520. diameter of clay particles

less than 0.005 millimeters (USQRG:30,1,0)
521. permeability level of clay

low (USQRG:30,1,0)
522. relationship between pore size and permeability

smaller pore size lowers permeability (USQRG:30,1,0)
523. diameter of sand particles

0.06 to 2 millimeters (USQRG:30,1,1)
524. relative size of gravel pores

very large (USQRG:30,1,1)
525. Why do molecular forces of attraction not lower the permeability of sand?

films of water adhering to adjacent grains cannot span the wider pores, allowing water to move freely (USQRG:30,1,1)
526. Why does gravel make a good building material for wells?

has high permeability due to large pores, allowing large amounts of water into the well (USQRG:30,1,1)
527. process that resulted in the presence of clay in most soil

chemical weathering of bedrock (USQRG:30,1,2)
528. Why is most soil less permeable than its underlying rock?

presence of fine clay particles (USQRG:30,1,2)
529. force that keeps some rainwater in topsoil

molecular attraction (USQRG:30,1,2)
530. two processes through which the rainwater retained by topsoil returns to the atmosphere

evaporation and transpiration (USQRG:30,2,0)
531. force that channels most rainwater to the water table

gravity (USQRG:30,2,1)
532. underground zone that is mostly dry between rains

zone of aeration (USQRG:30,2,1)
533. percolation (in geology)

movement of groundwater in the saturated zone (USQRG:30,2,2)
534. process similar to the flow of water after gently squeezing a saturated sponge

percolation (USQRG:30,2,2)
535. type of path by which groundwater moves through small pores during percolation

parallel and threadlike (USQRG:30,2,2)
536. Why does percolation stop on the sides of pores in rocks?

molecular attraction (USQRG:30,2,2)
537. general direction of groundwater percolation

toward surface streams and lakes (USQRG:30,2,3)
538. two types of paths taken by groundwater during percolation

directly moving along the water table and flowing along long, curving paths deep underground (USQRG:30,2,3)
539. force that deep groundwater paths resist to flow into surface streams

gravity (USQRG:31,1,0)
540. altitudes at which upward flow of groundwater into streams is possible

all altitudes (USQRG:31,1,0)
541. Why is upward flow of groundwater into streams possible?

water in the saturated zone is under greater pressure beneath a hill than beneath a stream (USQRG:31,1,0)
542. type of path along which most of the groundwater that enters a stream travels

shallow path not far beneath the water table (USQRG:31,1,0)
543. recharge (of groundwater)

replenishment of groundwater through rainfall and snowmelt entering the ground (USQRG:31,1,1)
544. groundwater recharge areas

regions of the ground in which precipitation seeps beneath the surface to the saturated zone (USQRG:31,1,1)
545. groundwater discharge areas

regions in which subsurface water is discharged to streams, lakes, ponds, or swamps (USQRG:31,1,1)
546. surface area of groundwater recharge areas compared to that of discharge areas

larger (USQRG:31,2,0)
547. speed of groundwater as it moves from recharge to discharge areas

slow (USQRG:31,1,1)
548. two factors that affect the time it takes water to move from a recharge area to a discharge area

rates of flow and distance to be travelled (USQRG:31,2,1)
549. the minimum amount of time for water to travel from a recharge area to a discharge area

several days (USQRG:31,2,1)
550. the longest amount of time water could take to travel from a recharge area to a discharge area

thousands of years (USQRG:31,2,1)
551. parts of a humid landscape considered recharge areas

entire landscape beyond streams and their floodplains (USQRG:31,2,2)
552. alluvial fans
- loose rock material forming a sloping, fan‐shaped mass at the point where a stream emerges from an upland area into a valley (USQRG:31,2,2;
- USQRG:101,1,1)
553. three parts of an arid landscape encompassed by recharge areas

mountains, bordering alluvial fans, and river channels with alluvium beds (USQRG:31,2,2)
554. type of rock strata in which downward and upward percolation is more efficient

most porous (USQRG:31,fig)
555. How do river channels with permeable alluvium beds act as recharge areas in arid regions?

water leaks downward through the alluvium, recharging the groundwater (USQRG:31,2,2)
556. two common ways people obtain groundwater

natural springs or excavating wells that reach an underground body of water (USQRG:32,1,1)
557. frequency of direct recharge in arid regions

infrequently or minimally (USQRG:32,1,fig)
558. consequence of periods of low recharge flow in arid regions

streams lose water as it seeps downward to resupply groundwater (USQRG:32,1,fig)
559. spring

a flow of groundwater emerging naturally at surface level (USQRG:32,1,2)
560. simplest type of spring

one that issues at an intersection of the land surface and water table (USQRG:32,1,2)
561. kinds of rocks in which small springs are found

all (USQRG:32,1,2)
562. three most common rocks in which large springs are found

lava, limestone, and gravel (USQRG:32,1,2)
563. common reason for the localization of springs

vertical or horizontal change in permeability (USQRG:32,1,3)
564. result of a porous limestone layer above an impermeable shale layer at the water table

a spring (USQRG:32,2,fig)
565. aquiclude

layer of impermeable rock adjacent to a permeable layer (USQRG:32,1,3; USQRG:101,1,5)
566. fault (in geology)

plane within rocks along which movement has taken place (USQRG:32,1,3; USQRG:101,2,15)
567. result of water percolating downward through a porous sand and meeting an underlying impermeable clay

flows laterally, creating a spring where the sand‐clay boundary meets the land surface (USQRG:32,1,3)
568. condition that must be met for a well to supply water

intersects the water table (USQRG:33,1,1)
569. rate of withdrawal of water from a new well compared to the rate of local groundwater flow

greater (USQRG:33,1,2)
570. effect of water being pumped from a new well

cone of depression forms around the well (USQRG:33,1,2)
571. cone of depression

conical indentation in the water table surrounding a new well after it begins operating (USQRG:33,1,2)
572. How obvious are cones of depression in most small domestic wells?

“barely discernible” (USQRG:33,2,0)
573. Why does a cone of depression increase the flow of water to a well?

locally steepened slope of the water table (USQRG:33,1,2)
574. effect on hydraulic gradient once the rate of inflow of a new well matches the rate of withdrawal

stabilization (USQRG:33,2,0)
575. effect of the wet season on the rate of groundwater recharge

increases (USQRG:33,fig)
576. slope of the hydraulic gradient during the wet season

relatively steep (USQRG:33,fig)
577. effect of increased pumping of a well during the dry season on a cone of depression

increases in size (USQRG:33,fig)
578. Why are most igneous and metamorphic rocks not very permeable?

small and constricted mineral grains (USQRG:34,1,0)
579. feature of large masses of igneous and metamorphic rocks that allow free circulation of groundwater

openings, such as fissures and joints (USQRG:34,1,0)
580. perched water body

body of water that lies on top of an aquiclude, above the main water table (USQRG:34,1,1)
581. condition necessary for a perched water body to occur

impermeable layer of rock or sediment in the zone of aeration (USQRG:34,1,1)
582. aquifer

body of highly permeable rock lying in the zone of saturation (USQRG:34,1,2)
583. original language of the word “aquifer”

Latin (USQRG:34,1,2)
584. Latin meaning of the word “aquifer”

water carrier (USQRG:34,1,2)
585. three rock types that are generally good aquifers

gravel, sand, and sandstone (USQRG:34,1,2)
586. material whose presence reduces the quality of sandstone as an aquifer

cement (USQRG:34,1,2)
587. How does a cementing agent reduce the quality of sandstone as an aquifer?

reduction of the diameter of openings in the stone (USQRG:34,2,0)
588. unconfined aquifer

aquifer in direct contact with the atmosphere (USQRG:34,2,1)
589. confined aquifer

aquifer bounded by aquicludes (USQRG:34,2,1)
590. approximate percentage of groundwater used in irrigation obtained from the High Plains aquifer in the United States

30 (USQRG:34,2,2)
591. What type of aquifer is the High Plains aquifer?

unconfined aquifer (USQRG:34,2,2)
592. average depth of the High Plains aquifer

approximately 65 meters (USQRG:34,2,2)
593. number of wells that tap the High Plains aquifer

approximately 170,000 wells (USQRG:34,2,2)
594. two most common types of rocks in the High Plains aquifer

sandy and gravelly (USQRG:34,2,2)
595. two geological ages during which most of the rocks in the High Plains aquifer were formed

Tertiary and Quarternary (USQRG:34,2,2)
596. average rate of water flow through the High Plains aquifer

30 centimeters per day (USQRG:34,2,2)
597. orientation of the water table in the High Plains aquifer

west to east (USQRG:34,2,2)
598. Through what two means is the High Plains aquifer recharged?

direct precipitation and seepage from streams (USQRG:34,2,2)
599. first decade in which the groundwater High Plains aquifer was tapped for irrigation

the 1930s (USQRG:34,2,3)
600. original reason for the High Plains aquifer being used for irrigation

severe regional droughts (USQRG:34,2,3)
601. decade of the second peak in demand for irrigation water from the High Plains aquifer

the 1950s (USQRG:34,2,3)
602. rate of annual recharge of the High Plains aquifer compared to the rate of water being withdrawn

much less (USQRG:34,2,3)
603. inevitable result of the net yearly withdrawal of water from the High Plains aquifer

long‐term fall in the water table level (USQRG:34,2,3)
604. three American states in which the thickness of the saturated zone has fallen by more than 50% in the past 50 years

Kansas, New Mexico, and Texas (USQRG;34,2,3)
605. part of metamorphic and igneous rocks that must be penetrated by a well to produce water

fractures (USQRG:34,fig)
606. eight states lying within the High Plains aquifer

South Dakota, Wyoming, Nebraska, Colorado, Kansas, Oklahoma, New Mexico, and Texas (USQRG:35,fig)
607. Which state’s land area lies mostly within the High Plains aquifer?

Nebraska (USQRG:35,fig)
608. direction of water flow in the High Plains aquifer, in relation to contour lines

perpendicular (USQRG:35,fig)
609. three rivers in Wyoming and Nebraska contained within the High Plains aquifer

North Platte, North Loop, and Elkton (USQRG:35,fig)
610. two geological time intervals in which the bedrock found beneath the High Plains aquifer in Wyoming and Nebraska formed

Tertiary and Upper Cretaceous (USQRG:35,fig)
611. two direct effects of reduced thickness of the saturated zone on aquifers

decreased water yield and increased pumping costs (USQRG:36,1,0)
612. home state of the Dakota aquifer

South Dakota (USQRG:36,1,1)
613. What type of aquifer is the Dakota aquifer?

confined (USQRG:36,1,1)
614. mountain range to the west of the Dakota aquifer

the Black Hills (USQRG:36,1,1)
615. two geographical features forming the land surface of the Black Hills

permeable strata and bounding aquicludes (USQRG:36,1,1)
616. two types of stone in the aquifer units of the Dakota aquifer

sandstone and limestone (USQRG:36,fig)
617. location at which rain must fall to recharge the Dakota aquifer

permeable units at the surface (USQRG:36,1,1)
618. role of aquicludes in the Dakota aquifer

confining units (USQRG:36,fig)
619. river east of the Black Hills that is part of the Dakota aquifer system

Missouri (USQRG:36,fig)
620. uplift portion of the Dakota aquifer system

Sioux Uplift (USQRG:36,fig)
621. direction of groundwater flow in the Dakota aquifer

east (USQRG:36,1,1; USQRG:36,fig)
622. direction of water flow during percolation into a confined aquifer

downward (USQRG:36,1,2)
623. type of pressure that increases as water descends in a confined aquifer

hydrostatic (USQRG:36,1,2)
624. reason water rises in a well drilled into a confined aquifer

pressure difference between the water table in the recharge area and the well intake (USQRG:36,2,0)
625. maximum height of water in a well drilled into a confined aquifer

level of the water table in the recharge area (USQRG:36,2,0)
626. condition necessary for water to flow out of a well drilled into a confined aquifer without pumping

top of the well located at a lower altitude than the recharge area (USQRG:36,2,0)
627. artesian aquifer

aquifer in which the discharge area is lower than the recharge area such that water naturally rises to the surface when tapped (USQRG:36,2,0)
628. artesian well

well drilled into an artesian aquifer, allowing water to rise naturally to the surface (USQRG:36,2,0)
629. artesian spring

freely flowing spring supplied by an artesian aquifer (USQRG:36,2,0)
630. city from which the term “artesian” is derived

Artois, France (USQRG:36,2,0)
631. Roman name for the city of Artois

Artesium (USQRG:36,2,0)
632. Why was the term “artesian” derived from the name of a city?

Artesian flow was first studied in Artois. (USQRG:36,2,0)
633. maximum height of a fountain created by artesian water pressure under ideal conditions

60 meters (USQRG:36,2,0)
634. condition necessary for artesian springs and fountains to maintain their free flow of water

recharge to the system matches outflow (USQRG:36,2,0)
635. advantage of tapping artesian wells and springs

avoid the cost of pumping (USQRG:36,2,0)
636. major source of water in dry regions of western North America

groundwater (USQRG:37,1,1)
637. average discharge of aquifer systems in dry regions of western North America

low (USQRG:37,1,1)
638. two conditions necessary for an artesian system

confined aquifer and water pressure sufficient to make the water in a well rise above the surface (USQRG:37,fig)
639. height to which water in a nonartesian well rises

height of the water table in the recharge area, less water loss due to friction of percolation (USQRG:37,fig)
640. How is the amount of water available from groundwater sources in dry regions of western North America changing?

steadily diminishing (USQRG:37,1,1)
641. nonrenewable resources

natural supplies formed only over geologically long intervals of time (USQRG:37,1,1)
642. three nonrenewable resources being used at unsustainable rates

petroleum, minerals, and groundwater (USQRG:37,1,1)
643. time scale needed to restore some aquifers to their original state

centuries or millennia (USQRG:37,1,1,)
644. possible result if groundwater withdrawal from a spring exceeds recharge

drying up, if the water table no longer intersects the surface (USQRG:37,2,1)
645. process that can halt the fall of the water table

artificial recharge (USQRG:37,2,2)
646. method of artificial recharge of groundwater involving food processing plants

spraying biodegradable liquid waste from a food processing plant over the land surface (USQRG:37,2,2)
647. type of process that removes pollutants from biodegradable liquid waste as it percolates toward the groundwater

biological (USQRG:37,2,2)
648. method of artificial recharge of groundwater involving urban areas

channeling runoff from rainstorms in urban areas into basins for percolation into the groundwater (USQRG:38,1,0)
649. injection wells

wells used to pump groundwater back into the ground after being used for nonpolluting industrial purposes (USQRG:38,1,0)
650. zone recharged by injection wells

saturated zone (USQRG:38,1,0)
651. action that accelerated the tilting of the Leaning Tower of Pisa

withdrawal of groundwater from aquifers (USQRG:38,2,fig)
652. country of the Leaning Tower of Pisa

Italy (USQRG:38,2,fig)
653. force that supports the weight of overlying rocks or sediments in an aquifer

water pressure in the pores of an aquifer (USQRG:38,1,1)
654. effect on water pressure of the withdrawal of groundwater from an aquifer

reduction (USQRG:38,1,1)
655. effect on aquifer particles of the withdrawal of groundwater from an aquifer

slight shifting (USQRG:38,1,1)
656. effect on the land surface particles of the withdrawal of groundwater from an aquifer

subsiding (USQRG:38,1,1)
657. three factors affecting the amount of land subsidence when groundwater is withdrawn from an aquifer

reduction of water pressure, thickness of the aquifer, and compressibility of the aquifer (USQRG:38,1,1)
658. region of the United States with widespread land subsidence due to withdrawal of groundwater

southwestern (USQRG:38,1,1)
659. effect on land subsidence in areas subject to flooding in the United States

increase (USQRG:38,1,1)
660. type of area in which land subsidence is “especially damaging,” according to Skinner

regions in which water is pumped from beneath cities (USQRG:38,1,2)
661. ancient Aztec capital

Tenochtitlan (USQRG:38,1,2)
662. modern‐day city on top of the ancient Aztec capital Tenochtitlan

Mexico City (USQRG:38,1,2)
663. unique geographic feature of the ancient Aztec capital

situated in the middle of a shallow lake (USQRG:38,1,2)
664. effect of rapid withdrawal of groundwater around Mexico City on porous lake sediments

compression (USQRG:38,1,2)
665. year in which construction on the Leaning Tower of Pisa began

1174 (USQRG:38,1,2)
666. type of sediments on which the Leaning Tower of Pisa was built

unstable fine‐grained floodplain (USQRG:38,1,2)
667. century in which the tilting of the Leaning Tower of Pisa rapidly increased

20th (USQRG:38,1,2)
668. recent improvement to the Leaning Tower of Pisa to keep it stable

strengthening of the foundation (USQRG:38,1,2)
669. action necessary to keep the Leaning Tower of Pisa stable

strict controls on the withdrawal of groundwater (USQRG:38,1,2)
670. three causes for contamination of drinking water

natural dissolved substances, human waste products, and industrial waste products (USQRG:38,1,3)
671. seven most common compounds dissolved in groundwater

chlorides; sulfates; calcium, magnesium, sodium, potassium, and iron bicarbonates (USQRG:38,1,4)
672. origin of dissolved compounds in groundwater

weathered rocks (USQRG:38,2,0)
673. chief determinant of the composition of groundwater

composition of the rock in which water occurs (USQRG:38,2,0)
674. two rocks containing much of the groundwater of the central United States

limestone and dolostone (USQRG:38,2,0)
675. two compounds found in high amounts in groundwater of the central United States

calcium and magnesium bicarbonates (USQRG:38,2,0)
676. hard water

water rich in calcium and magnesium bicarbonates (USQRG:38,2,0)
677. two reasons bathing in hard water is frustrating

soap does not lather easily and a crustlike ring forms in the tub (USQRG:38,2,0)
678. depositions made by hard water in pipes

scaly crusts (USQRG:38,2,0)
679. soft water

water with little dissolved matter and no appreciable calcium (USQRG:38,2,0)
680. two rocks commonly associated with soft water

greywacke sandstone and volcanic rocks (USQRG:38,2,0)
681. region of the United States with generally soft water

northwestern (USQRG:38,2,0)
682. What event occurs when groundwater flows through rocks containing noxious elements?

Particles from the rocks dissolve into the water, making it unsuitable for consumption. (USQRG:38,2,1)
683. chemical formula of hydrogen sulfide

H2S (USQRG:39,1,0)
684. odor of hydrogen sulfide

rotten eggs (USQRG:39,1,0)
685. type of rock from which hydrogen sulfide in groundwater is derived

sulfur‐rich (USQRG:39,1,0)
686. two compounds that are highly concentrated in arid regions, occasionally making groundwater non‐potable

sulfates and chlorides (USQRG:39,1,0)
687. type of compound groundwater releases from porous sedimentary rocks in very dry regions

salts (USQRG:39,1,0)
688. zone in which groundwater deposits salts in very dry regions

zone of aeration (USQRG:39,1,0)
689. effect of salt on soil with regard to agriculture

makes soil unsuitable for agriculture (USQRG:39,1,0)
690. most common source of water pollution in wells and springs

sewage (USQRG:39,1,1)
691. size of pores in coarse gravel or cavernous limestone

large (USQRG:39,1,1)
692. four potential sources of groundwater contamination from sewage

septic tanks, broken sewers, privies, and barnyards (USQRG:39,1,1)
693. minimum distance needed for sewage‐contaminated groundwater to be purified

30 meters (USQRG:39,2,0)
694. mineral that purifies sewage‐contaminated groundwater relatively quickly

sand (USQRG:39,2,0)
695. distance for which sewage‐contaminated groundwater remains polluted in coarse gravel, relative to sand

long distance (USQRG:39,1,1)
696. substance used by purification plants to treat municipal water supplies and sewage

sand (USQRG:39,2,0)
697. three ways in which sand purifies groundwater

mechanically filtering out bacteria, oxidizing bacteria, and placing bacteria in contact with other organisms that will consume them (USQRG:39,2,0)
698. effect of oxidation on bacteria

They are rendered harmless. (USQRG:39,2,0)
699. substance forming a barrier between fresh groundwater and seawater along coasts

brackish water (USQRG:39,2,1)
700. thickness of the barrier between fresh groundwater and seawater along coasts

thin (USQRG:39,2,1)
701. effect of pumping an aquifer near the coast on the flow of fresh groundwater to the sea

reduction (USQRG:39,2,1)
702. effect of pumping an aquifer near the coast on the flow of saltwater to the sea

increase landward toward permeable strata (USQRG:39,2,1)
703. eventual result of excessive pumping from aquifers near the coast

seawater intrusion (USQRG:40,1,0)
704. seawater intrusion

salt water encroaching inland and contaminating freshwater supplies (USQRG:40,1,0)
705. difficulty of reversing seawater intrusion

very difficult (USQRG:40,1,0)
706. two types of landfills

open basins and excavations (USQRG:40,1,1)
707. step taken after a landfill reaches capacity

covered with dirt (USQRG:40,1,1)
708. process allowed to take place after a landfill reaches capacity

revegetation (USQRG:40,1,1)
709. How are waste products in covered landfills mobilized?

water seepage carries away soluble substances in the waste products (USQRG:40,1,1)
710. factor determining the direction of flow of contaminated water from landfills

regional groundwater flow pattern (USQRG:40,1,1)
711. rate at which contaminated water from landfills disperses

same rate as percolating water in groundwater systems (USQRG:40,1,1)
712. two goals of a United States government program tackling pollution from landfill waste

clean up landfills and render them environmentally safe (USQRG:40,1,2)
713. number of United States landfill sites identified to be creating pollution

tens of thousands (USQRG:40,2,0)
714. two aspects of plants pesticides and herbicides are used to improve

quality and productivity (USQRG:40,2,1)
715. two chief problems pesticides and herbicides can cause in humans

cancer and birth defects (USQRG:40,2,1)
716. event that marked a dramatic drop in the United States population of bald eagles

introduction of pesticides into the natural food chain (USQRG:40,2,1)
717. pesticide mainly responsible for the reduction of the United States population of bald eagles

DDT (USQRG:40,2,1)
718. reason pesticides reach groundwater

precipitation flushes them into the soil (USQRG:40,2,1)
719. zone that disappears during excessive pumping of a coastal well

brackish transition zone (USQRG:40,fig)
720. point at which salt water and fresh water come into contact during limited pumping of a coastal well

right before pumping (USQRG:40,fig)
721. leading environmental concern of industrialized countries

necessity of dealing with highly toxic industrial wastes (USQRG:40,2,2)
722. two short‐term results of surface dumping of highly toxic industrial waste

contamination of surface and subsurface water supplies (USQRG:40,2,2)
723. long‐term result of surface dumping of highly toxic industrial waste

serious and potentially fatal health problems (USQRG:40,2,2)
724. environmental problem unique to nuclear‐capable countries

disposal of radioactive waste products (USQRG:40,2,2)
725. two especially radioactive isotopes

90Sr and 137Cs (USQRG:40,2,2)
726. amount of 90Sr required in the surface environment to be fatal to humans

“minute quantities” (USQRG:41,1,0)
727. two categories of hazardous wastes

toxic and radioactive (USQRG:41,1,1)
728. conclusion of most feasibility studies of the disposal and storage of hazardous wastes

Underground storage is appropriate, assuming safe sites can be found. (USQRG:41,1,1)
729. maximum time span high‐level nuclear wastes can remain dangerous

hundreds of thousands of years (USQRG:41,1,1)
730. reason high‐level nuclear wastes remain dangerous for extended very long time

the long half‐lives of some radioactive isotopes (USQRG:41,1,1)
731. primary requirement for sites for high‐level nuclear waste disposal

stability over a very long time span (USQRG:41,1,1)
732. three criteria for completely safe sites for high‐level nuclear waste disposal

immune from chemical changes by groundwater, physical changes by earthquakes, or disruptions by humans (USQRG:41,1,1)
733. most immediate area of concern in placing hazardous wastes underground

groundwater (USQRG:41,2,0)
734. What type of solvent is water?

nearly universal (USQRG:41,2,0)
735. How acidic or basic is most groundwater?

weakly acidic (USQRG:41,2,0)
736. Why is any underground container of hazardous waste likely to corrode?

the acidity of passing groundwater (USQRG:41,2,0)
737. rate of circulation of water present in crustal rocks

1 to 50 meters per year (USQRG:41,2,0)
738. ideal level of fracturing in the rock enclosing an underground radioactive waste storage site

very low (USQRG:41,2,2)
739. ideal permeability of the rock enclosing an underground radioactive waste storage site

low (USQRG:41,2,3)
740. ideal economic mineral potential of the rock enclosing an underground radioactive waste storage site

none (USQRG:41,2,3)
741. relative rainfall in the area of an ideal underground radioactive waste storage site

low (USQRG:42,1,3)
742. relative thickness of the zone of aeration in an ideal underground radioactive waste storage site

thick (USQRG:42,1,4)
743. relative erosion rate in an ideal underground radioactive waste storage

very low (USQRG:42,1,5)
744. ideal probability of earthquakes or volcanic activity in an underground radioactive waste storage site

very low (USQRG:42,1,6)
745. knowledge needed by geologists to predict future geological events

local and regional groundwater conditions (USQRG:42,1,8)
746. three areas that geologists need to understand to predict future conditions in a underground waste storage site
- response of groundwater systems to crustal movements, local and global climatic change, and other factors affecting the site’s stability
- (USQRG:42,1,8)
747. feature in surface landfill which makes it safer than an open waste pond

fully lined, preventing downward seepage of wastes (USQRG:41,fig)
748. type of rock unit required in the injection method of waste management

deep and confined (USQRG:41,fig)
749. structure that must be above a rock unit utilized in the injection method of waste management

aquifers used for water supplies (USQRG:41,fig)
750. Why is constant monitoring needed at injection wells used for waste management?

The injection method is not foolproof. (USQRG:41,fig)
751. When does rainwater begin to chemically weather regolith and bedrock?

as soon as it infiltrates the ground (USQRG:42,2,1)
752. dissolution

process of chemical weathering in which minerals and rock materials pass directly into solution (USQRG:42,2,1; USQRG:101,2,9)
753. type of rock in Earth’s crust that most easily undergoes dissolution

carbonates (USQRG:42,2,1)
754. three most common carbonate rocks

limestone, dolostone, and marble (USQRG:42,2,2)
755. solubility of carbonate minerals in pure water

nearly insoluble (USQRG:42,2,2)
756. relative proportion of the Earth’s surface underlain by limestone, dolostone, and marble

large majority (USQRG:42,2,2)
757. acid present in rainwater that dissolves carbonate minerals

carbonic (USQRG:42,2,2)
758. cations present in groundwater from the dissolution of carbonate minerals

calcium (USQRG:42,2,2)
759. anions present in groundwater from the dissolution of carbonate minerals

bicarbonate (USQRG:42,2,2)
760. portions of carbonate rocks that are most affected by groundwater weathering

joints and other partings (USQRG:42,2,3)
761. granite mineral largely resistant to weathering

quartz (USQRG:42,2,3)
762. result of limestone weathering

Nearly all the minerals dissolve away into slowly moving groundwater. (USQRG:42,2,3)
763. rate at which carbonate landscapes drop in temperate regions with high rainfall, vegetation level and water table

10 millimeters per 1,000 years (USQRG:43,1,0)
764. two processes through which the dissolution rate may exceed the average rate of surface erosion

mass‐wasting and sheet erosion (USQRG:43,1,0)
765. geological feature that may cause the dissolution rate to exceed the average rate of surface erosion

streams (USQRG:43,1,0)
766. substance responsible for most conversion of sediment in sedimentary rock

groundwater (USQRG:43,1,1)
767. most common type of iron compound in sedimentary rocks

hydroxides (USQRG:43,1,1)
768. saturated zone

region of the ground in which sediment is saturated with water (USQRG:43,1,1)
769. process by which loose sediment transforms into firm rock

substances in a groundwater solution are precipitated as cement between rock and mineral particles of sediment (USQRG:43,1,1)
770. three chief cementing substances in sedimentary rocks

quartz, calcite, and iron compounds (USQRG:43,1,1)
771. most common cementing substance in sedimentary rocks

calcite (USQRG:43,1,1)
772. replacement (in geology)

process in which a fluid dissolves existing matter and deposits an equal volume of a different substance (USQRG:43,1,2)
773. How do geologists know that replacement takes place on a volume‐for‐volume basis?

New material preserves the minutest textures of the material it replaces. (USQRG:43,1,2)
774. two types of substances that can undergo replacement

mineral and organic (USQRG:43,1,2)
775. common example of the replacement of organic matter

petrified wood (USQRG:43,1,2)
776. sinkhole

depression in the surface of the ground, often connecting to a cavern or other subterranean passage (USQRG:43,1,3; USQRG:103,1,9)
777. identifying characteristic of rocks in regions with many caves and sinkholes

exceptionally soluble (USQRG:43,1,3)
778. drainage pattern in regions with many caves and sinkholes

disrupted (USQRG:43,2,0)
779. geological features streams reappear as in landscapes with numerous caves and sinkholes

large springs (USQRG:43,2,0)
780. Karst topography

landform developed in areas underlain by easily dissolved rock; with many caves and sinkholes (USQRG:43,2,0; USQRG:102,1,11)
781. former country in which the Karst region lies

Yugoslavia (USQRG:43,2,0)
782. characteristic feature of the Karst region’s landscape

closely spaced sinkholes (USQRG:43,2,0)
783. most common type of rock in karst landscapes

carbonate (USQRG:43,2,0)
784. four types of rock in which karst landscapes may develop

carbonate, dolomite, gypsum, and salt (halite) (USQRG:43,2,0)
785. four criteria for a karst landscape

steep hydraulic gradient, sufficient precipitation, adequate soil and plant cover, and dissolution‐promoting temperatures (USQRG:43,2,1)
786. Why is a steep gradient necessary for a karst landscape?

allows groundwater to flow through soluble rock by the force of gravity (USQRG:43,2,1)
787. best climate and landscape for the development of a karst terrain

moist temperate to tropical regions with many thick, soluble rocks (USQRG:43,2,1)
788. most common type of karst landscape

sinkhole karst (USQRG:43,2,2)
789. sinkhole karst

landscape dotted with sinkholes of various sizes and shapes (USQRG:43,2,2)
790. three American states in which sinkhole karst landscapes are most common

Indiana, Kentucky, and Tennessee (USQRG:43,2,2)
791. island nation on which sinkhole karst landscapes are commonly found

Jamaica (USQRG:43,2,2)
792. cone karst

closely spaced conical‐ or pinnacle‐ shaped hills separated by deep sinkholes (USQRG:43,2,3)
793. tower karst

isolated tower‐like hills separated by expanses of alluvium (USQRG:43,2,3)
794. rock underlying cone and tower karst landscapes

thick, well‐jointed limestone (USQRG:43,2,3)
795. eventual result in a tower karst if the local drainage system does not remove sediment

Areas between towers form a flat alluvial surface. (USQRG:43,2,3)
796. two world regions in which cone and tower karst landscapes are most commonly found

Central America and the South Pacific (USQRG:43,2,3)
797. two Caribbean islands on which cone and tower karst landscapes are found

Cuba and Puerto Rico (USQRG:43,2,3)
798. Guilin’s country

China (USQRG:43,2,4)
799. type of karst landscape found near Guilin, China

tower karst (USQRG:43,2,4)
800. height of vertical‐sided peaks of limestone in the karst landscape near Guilin, China

200 meters (USQRG:45,1,6)
801. pavement karst

areas of bare limestone in which dissolution has etched and widened joints and bedding planes (USQRG:45,1,7)
802. What high‐latitude process increases the probability of a pavement karst forming?

Continental glaciations stripping away regolith, leaving carbonate bedrock exposed to weathering. (USQRG:45,1,7)
803. Greenland city known for its pavement karst landscapes

Spitzbergen (USQRG:45,1,7)
804. region of Ireland known for its pavement karst landscapes

Burren (USQRG:45,1,7)
805. element with atomic number 34

selenium (USQRG:43,1,4)
806. government agency that released the 1983 report on the devastation of wildlife in the Kesterson National Wildlife Refuge

U.S. Fish and Wildlife Service (USQRG:43,1,5)
807. What THREE effects did selenium poisoning have on Kesterson National Wildlife Refuge’s nesting waterfowl in the early 1980s?

high death rates, birth defects, and decreased hatching rates (USQRG:43,1,5)
808. Kesterson National Wildlife Refuge’s state

California (USQRG:43,1,5)
809. valley in which Kesterson National Wildlife Refuge is located

San Joaquin Valley (USQRG:43,1,5)
810. climate of western San Joaquin Valley

arid (USQRG:45,1,1)
811. effect of irrigation on the water table in San Joaquin Valley

rose significantly (USQRG:45,1,1)
812. method by which excess water due to irrigation in the San Joaquin Valley was removed

system of subsurface drains (USQRG:45,1,1)
813. natural source of selenium near San Joaquin Valley

Coast Ranges (USQRG:45,1,2)
814. annual rainfall of the Coast Ranges

less than 250 millimeters (USQRG:45,1,2)
815. annual evaporation rate of the Coast Ranges

approximately 2,300 millimeters (USQRG:45,1,2)
816. Why has selenium concentrated in the Kesterson Reservoir?

The reservoir has no outlet. (USQRG:45,1,2)
817. two chemical properties of the shallow groundwater of the San Joaquin Valley

alkaline and slightly to highly saline (USQRG:45,1,3)
818. relative solubility of selenium in the shallow groundwater of the San Joaquin Valley

high (USQRG:45,1,3)
819. depth of a clay layer beneath the San Joaquin Valley

3 to 23 meters (USQRG:45,1,4)
820. geographic feature resulting from the clay layer beneath the San Joaquin Valley

perched water body (USQRG:45,1,4)
821. paleogeography

geography of the past (USQRG:45,2,1)
822. record used to reconstruct ancient environments

stratigraphic (USQRG:45,2,1)
823. organisms whose skeletons form calcareous ooze on the deep sea floor

single‐celled plankton (USQRG:46,fig)
824. type of location at which coarse‐grained alluvial fans form

emergence of streams from mountains (USQRG:46,fig)
825. stone released by icebergs

dropstone (USQRG:46,fig)
826. climate of lakes in which seasonal varves form

cold (USQRG:46,fig)
827. geological feature that clogs braided streams

bar (USQRG:46,fig)
828. type of sand that accumulates in braided streams

cross‐bedded gravelly sand (USQRG:46,fig)
829. type of water from which evaporites precipitate in dry climates

hypersaline (USQRG:46,fig)
830. geological feature resulting from winds in barrier islands

cross bedded sand dunes (USQRG:46,fig)
831. geological feature on which oolites form in shallow tropical seas

shoals (USQRG:46,fig)
832. How does a tempestite form?

Sediment stirred up by a storm settles on the continental shelf or in a shallow sea. (USQRG:47,fig)
833. process by which cycles of graded beds form in a turbidite

Coarse‐grained sediments settle before fine‐grained sediments as turbidity currents slow down. (USQRG:47,fig)
834. animal category that creates mottled textures in sandy lagoon muds

burrowers (USQRG:47,fig)
835. two goals of paleogeography

understand the distribution of land and sea at a given time and identify localized environmental features of the past (USQRG:48,1,0)
836. lagoon

shallow pond or lake on the edge of the ocean but separated from it (USQRG:48,1,0; USQRG:102,1,13)
837. mammal once considered extremely similar to the largest dinosaurs

hippopotamus (USQRG:48,1,1)
838. object in soil around which white nodules of calcium carbonate form

plant roots (USQRG:48,1,fig)
839. type of sediment in which petroleum and natural gas tend to accumulate

porous (USQRG:48,2,0)
840. reef

sedimentary rock aggregate formed from skeletons of colonial organisms that lived below the surface of the ocean (USQRG:48,2,0; USQRG:103,1,1)
841. organisms that often construct limestone reefs in shallow seas

coral (USQRG:48,2,0)
842. actualism

studying modern deposition patterns to reconstruct ancient deposits in similar environments (USQRG:48,2,1)
843. coring

driving a tube into a sedimentary deposit to withdraw the contents (USQRG:48,2,1)
844. type of location at which coring is especially useful for examining deposits

center of a large body of water such as a lake, lagoon, or deep ocean (USQRG:48,2,1)
845. two pieces of information a core of sediment provides

sequence of deposition and a three‐dimensional picture of the deposit (USQRG:48,2,1)
846. two means by which geologists can examine a meandering river’s depositional record

dig pits in the adjacent valley floor or core the valley floor (USQRG:48,2,1)
847. animal whose burrows fossilized into “devil’s corkscrews”

beavers (USQRG:48,2,fig)
848. state whose grasslands were inhabited by beavers 20 million years ago

Nebraska (USQRG:48,2,fig)
849. type of environment that produced most coal deposits

swamps choked with vegetation (USQRG:48,2,2)
850. two types of locations in which swamps choked with vegetation are found

banks of rivers and marine lagoons (USQRG:49,1,0)
851. How do geologists conclusively determine the environment in which coal deposits were formed?

by evaluating the beds above and below the coal deposits (USQRG:49,1,0)
852. geological find in a coal deposit rock bed that indicates a marine lagoon lay near a swamp

fossils of marine animals (USQRG:49,1,0)
853. Lake Louise’s Canadian province

Alberta (USQRG:49,fig)
854. soil

loose sediment that contains organic matter accumulated in contact with the atmosphere, not underwater (USQRG:49,1,1)
855. two types of substances on which soil can rest

sediment or rock (USQRG:49,1,1)
856. two ways in which soil benefits plants

supplies essential nutrients and physically supports plants (USQRG:49,1,1)
857. two processes by which most soil forms

weathering and decay of plant material (USQRG:49,1,1)
858. topsoil

upper zone of many soils (USQRG:49,1,1)
859. three main components of topsoil

sand, clay, and humus (USQRG:49,1,1)
860. humus

organic matter that gives topsoil its dark color (USQRG:49,1,1)
861. process that creates humus

bacteria‐caused decay of plant debris (USQRG:49,2,0)
862. caliche

calcium carbonate precipitated as massive deposits due to groundwater evaporation (USQRG:49,2,1)
863. type of climate in which caliche forms

warm climates that are dry for part of the year (USQRG:49,2,1)
864. process that destroys humus

oxidization (USQRG:49,2,1)
865. type of climate in which humus is destroyed by warm water percolation

moist and tropical (USQRG:49,2,1)
866. laterites

soils rich in iron and aluminum oxides (USQRG:49,2,1)
867. color of laterites

rusty red (USQRG:49,2,1)
868. type of mineral that breaks down quickly under warm water percolation, creating laterites

silicate (USQRG:49,2,1)
869. process by which most soil is destroyed

erosion (USQRG:49,2,2)
870. reason ancient buried soils can be difficult to recognize and interpret

Chemical components are often altered beyond recognition. (USQRG:50,1,0)
871. type of location likely to contain an ancient soil

beneath an unconformity (USQRG:50,1,0)
872. two epochs in which “devil’s corkscrews” formed

Oligocene and Miocene (USQRG:50,1,0)
873. greatest distance underground that ancient beavers lived

10 meters (USQRG:50,1,0)
874. environmental role of freshwater lakes and glaciers

supply reservoirs on land (USQRG:50,1,1)
875. geological epoch in which lakes occupied a large fraction of Earth’s surface

none (USQRG:50,1,2)
876. Why are lake deposits more likely to survive erosion than soils?

Lakes form in basins that lie at lower elevations than most soils. (USQRG:50,1,2)
877. event indicated by historical presence of large freshwater lakes

abundant precipitation (USQRG:50,1,3)
878. method by which large freshwater lakes receive a substantial portion of their water

runoff from land (USQRG:50,1,3)
879. characteristic of large freshwater lakes that stabilizes the temperature of nearby land areas

high heat capacity of water (USQRG:50,1,3)
880. texture of sediments around the margins of a freshwater lake compared to those at the center

coarser (USQRG:50,1,4)
881. varves

alternating coarse‐ and fine‐grained layers resulting from seasonal depositions (USQRG:50,1,4)
882. type of season in which a freshwater lake receives almost all of its coarse sediment

moist (USQRG:50,1,4)
883. area of deep lakes at which wind‐driven waves touch the lake bottom

only approaching the shore (USQRG:50,1,4)
884. two types of exclusively marine fossils

corals and echinoderms (USQRG:50,1,5)
885. relative strength of waves and currents in lakes

generally weak (USQRG:50,2,0)
886. abundance of burrowing animals in marine environments compared to lakes

more frequent (USQRG:50,2,0)
887. continental shelf

gently sloping zone of shallowly submerged land surrounding the continents (USQRG:50,2,1; USQRG:101,1,17)
888. barrier commonly present in between deep‐sea deposits and lake deposits

unconformity (USQRG:50,2,1)
889. Why do glaciers formed in mountain valleys seldom leave enduring geologic records?

Mountains standing above the surrounding terrain erode rapidly. (USQRG:50,2,2)
890. time span for which records of continental glaciers survive

hundreds of millions of years (USQRG:50,2,2)
891. two modern continental glaciers

one occupying most of Greenland and one covering nearly all of Antarctica (USQRG:50,2,2)
892. natural method by which a glacier’s movement is recorded

Rocks embedded in the base of the glacier leave deep scratches in underlying rock. (USQRG:50,2,3)
893. till

unconsolidated, unsorted sediments deposited by glaciers (USQRG:50,2,4; USQRG:103,2,5)
894. tillite

lithified till (USQRG:50,2,4)
895. moraine

accumulation of sediment deposited at the farthest reach of a glacier (USQRG:50,2,4)
896. meltwater

streams issuing from the front of a retreating glacier (USQRG:50,2,4)
897. outwash

well‐stratified sediment found in meltwater consisting of gravel, cross‐bedded sand, and mud (USQRG:50,2,4)
898. geological feature often formed in front of a retreating glacier

lake (USQRG:50,2,5)
899. season in which coarse sediment layers form in glacial lakes

summer (USQRG:50,2,5)
900. material carried into glacial lakes by meltwater in the summer

sand (USQRG:51,1,0)
901. season in which fine layers of sediment form in glacial lakes

winter (USQRG:51,1,0)
902. process by which fine layers of sediment form in glacial lakes

Suspended clay and organic matter settle slowly in the lake’s still water. (USQRG:51,1,0)
903. How does abundant organic matter in glacial lakes’ sediment layers affect the lakes’ color?

darkens (USQRG:51,1,0)
904. time span represented by a pair of sediment layers in a glacial lake

1 year (USQRG:51,1,0)
905. pieces of glacier that break off into lakes or oceans

icebergs (USQRG:51,1,1)
906. two characteristics of glacial till

tightly packed and coarse (USQRG:51,1,1)
907. dropstone

glacial sediment dropped into a lake or ocean (USQRG:51,1,1)
908. ice rafting

icebergs breaking off from glaciers, resulting in the deposition of large stones in lakes or oceans (USQRG:51,1,1)
909. frequency of organic matter in desert soils

low (USQRG:51,1,2)
910. source of organic matter in soils

vegetation (USQRG:51,1,2)
911. two processes caused by desert rain

erosion and deposition of sediment (USQRG:51,1,2)
912. geological feature that carries chemical products of weathering to desert basins

temporary streams (USQRG:51,1,2)
913. exterior drainage

runoff water and sediment from beyond a region’s borders (USQRG:51,1,2)
914. type of region that experiences exterior drainage

humid (USQRG:51,1,2)
915. interior drainage

pattern in which streams dry up through evaporation, seepage into dry terrain, or drainage into lakes (USQRG:51,1,2)
916. type of region that experiences interior drainage

arid (USQRG:51,1,2)
917. playa lakes

lakes in areas with interior drainage (USQRG:51,1,2)
918. How permanent are playa lakes?

temporary (USQRG:51,1,2)
919. dune

hill of loose sand formed by the wind (USQRG:51,1,3; USQRG:101,2,11)
920. type of region in which dunes form

dry and sparsely vegetated (USQRG:51,1,3)
921. percentage of deserts occupied by dunes

less than 1 (USQRG:51,1,3)
922. direction in which a dune crawls

downwind (USQRG:51,1,3)
923. method by which a dune crawls

the wind sweeps sand up and over the top of the dune, depositing it downwind (USQRG:51,1,3)
924. trough cross‐stratification

new sets of sediment beds accumulating on a curved surface, cutting through older sets (USQRG:51,2,0)
925. part of a dune at which a windstream becomes compressed

just above (USQRG:51,fig)
926. point at which a dune stops growing

The height causes the windstream to move rapidly enough to transport sand. (USQRG:51,fig)
927. Which side of a dune has a steep slope?

downwind or leeward (USQRG:51,fig)
928. climate typified by Death Valley

arid basin (USQRG:52,1,1)
929. Death Valley’s state

California (USQRG:52,1,1)
930. geological belt in which dry climates are commonly found

trade wind (USQRG:52,1,0)
931. mountain feature that creates dry climates

rain shadow (USQRG:52,1,0)
932. alluvial fans

loose rock material forming a sloping, fan‐shaped mass where streams emerge into a valley (USQRG:52,1,1; USQRG:101,1,1)
933. type of particles that form alluvial fans

poorly sorted and sedimentary (USQRG:52,1,1)
934. type of material in alluvial fans near the source area

range from boulders to sand (USQRG:52,2,0)
935. type of material in alluvial fans on low, gentle slopes

range from sand to mud (USQRG:52,2,0)
936. braided stream

stream in which sand bars cause a series of separating and uniting channels (USQRG:52,2,0)
937. direction of flow of a braided stream in an arid basin

toward the center (USQRG:52,2,1)
938. minerals accumulated as a playa lake dries up

evaporite (USQRG:52,2,1)
939. three chief evaporites in Death Valley

halite, gypsum, and anhydrite (USQRG:52,2,1)
940. salt pans

large polygonal mudcracks formed in arid basins by alternate wetting and drying (USQRG:53,1,0)
941. geological feature formed by calcium carbonate deposition near salt pans

caliche (USQRG:53,1,0)
942. type of drainage normally present in areas with abundant rainfall

exterior (USQRG:53,1,1)
943. location of alluvial fans in moist regions

at the foot of mountains and steep hills (USQRG:53,1,2)
944. slope of alluvial fans in moist regions compared to those in arid regions

gentler (USQRG:53,1,2)
945. level of vegetation on alluvial fans

poor (USQRG:53,1,2)
946. reason for the level of vegetation present on alluvial fans

steep slopes (USQRG:53,1,2)
947. two events that trigger the formation of braided streams in alluvial fans in moist regions

heavy rainfall or snowmelt (USQRG:53,1,2)
948. type of glaciers that form braided streams

those that experience substantial melting in summer (USQRG:53,1,2)
949. meandering rivers

streams that occupy solitary channels, winding back and forth like ribbons (USQRG:53,1,3)
950. two large meandering rivers

Mississippi and Thames (USQRG:53,1,3)
951. amount of sediment in meandering rivers compared to that in braided streams

significantly lower (USQRG:53,1,3)
952. Why are meandering rivers not choked with sediment?

Sediment enters the river at a much slower rate than the flow of water (USQRG:53,1,3)
953. cause of curvature in a meandering river

any irregularity in the local terrain (USQRG:53,1,3)
954. speed of flow near the inside of a bend in a meandering river compared to that of the outside

significantly lower (USQRG:53,1,3)
955. Which bank does a meandering river cut into when rounding a bend?

outer (USQRG:53,1,3)
956. point bar

deposition of sediment in the inside of a bend in a meandering river (USQRG:53,1,3)
957. most common substance in point bars

sand (USQRG:53,1,4)
958. arrangement of minerals in point bars

cross‐bedded (USQRG:53,1,4)
959. two minerals commonly found on the riverbed of deep meandering rivers

gravel and sand (USQRG:53,1,3)
960. Why does mud not settle in a meandering river?

consists of very fine particles (USQRG:53,2,1)
961. floodplains

lowlands adjacent to a meandering river (USQRG:53,2,1)
962. backswamps

lowlands adjacent to a meandering river (USQRG:53,2,1)
963. rate of flow of floodwaters in floodplains

slow (USQRG:53,2,1)
964. change in flow rate of floodwaters further away from floodplain channels

decreasing (USQRG:53,2,1)
965. first two materials deposited by floodwaters in floodplains

sand and silt (USQRG:53,2,1)
966. natural levee

gentle ridge of sand and silt beside a river channel and floodplains (USQRG:53,2,1)
967. geological feature that eventually forms over point‐bar depositions

floodplains (USQRG:53,fig)
968. frequency of flooding for natural levees and floodplains

only periodically (USQRG:53,fig)
969. geological feature formed when floodplains and natural levees dry out

mudcracks (USQRG:54,1,0)
970. What record shows the earlier existence of moisture‐loving plants on floodplains?

traces of roots in the rock record (USQRG:54,1,0)
971. mineral formed by deposits of plants

coal (USQRG:54,1,0)
972. type of sequence in which sediments are deposited by a meandering river

vertical (USQRG:54,1,0)
973. sediment at the bottom of deposits made by a meandering river

coarse channel deposits (USQRG:54,1,1)
974. sediment at the middle of deposits made by a meandering river

cross‐bedded point‐bar sands (USQRG:54,1,1)
975. sediment at the top of deposits made by a meandering river

muddy backswamp deposits (USQRG:54,1,1)
976. location of levee sediments in the deposits of a meandering river

between cross‐bedded and backswamp deposits (USQRG:54,1,1)
977. Walther’s law

If deposition areas migrate laterally, sediments of one area settle on top of sediments of an adjacent area. (USQRG:54,1,1)
978. subsiding basin

basin sinking relative to the surrounding terrain (USQRG:54,1,2)
979. sedimentary cycle

coarse‐to‐fine composite depositional unit from a meandering river (USQRG:54,1,2)
980. Why are many cycles of migrating channels only partially preserved?

A channel can cut deeply, removing the uppermost and some lower deposits. (USQRG:54,1,2)
981. location that a river in a moist region deposits its entire load of sediment

a lake or the sea (USQRG:54,1,3)
982. pattern of sediment deposition at the end of a river

fanlike (USQRG:54,1,4)
983. result of a current reaching the end of a river

dissipation (USQRG:54,1,4)
984. delta

depositional body of sand, silt, and clay formed when a river deposits it sediment (USQRG:54,1,4; USQRG:101,2,7)
985. How did a delta get its name?

resemblance to the Greek letter delta (Δ) (USQRG:54,1,4)
986. type of area in which most large, well‐preserved deltas formed

points at which sizable rivers emptied into ancient seas (USQRG:54,1,4)
987. three deposits of a delta structure

delta‐plain, delta‐front, and prodelta (USQRG:54,2,0)
988. delta‐plain beds

delta deposits consisting mostly of sand and silt (USQRG:54,2,1)
989. orientation of delta‐plain beds

horizontal, except for a few cross‐bedded areas (USQRG:54,2,1)
990. distributary channels

smaller channels branched from the main river channel that radiate outwards in a delta (USQRG:54,2,1)
991. material that forms the floor of distributary channels

cross‐bedded sand (USQRG:54,2,1)
992. two geological features found between distributary channels

natural levees and swamps (USQRG:54,2,1)
993. delta‐front beds

delta deposits sloping seaward from the delta plain (USQRG:54,2,2)
994. two main materials in delta‐front beds

silt and clay (USQRG:54,2,2)
995. environmental system in which delta‐front beds fully lie

marine (USQRG:54,2,2)
996. type of organisms found in delta‐front muds

marine fauna (USQRG:54,2,2)
997. fragments often found in delta‐front muds

waterlogged wood (USQRG:54,2,2)
998. prodelta beds

farthest delta bed, spreading seaward at a low angle (USQRG:55,1,1)
999. material that forms most prodelta beds

clay (USQRG:55,1,1)
1000. event that causes silt to be deposited in delta‐front beds, even during floods

the abrupt slowdown of distributary channels (USQRG:55,2,0)
1001. density of freshwater compared to sea water

less dense (USQRG:55,2,0)
1002. progradation

seaward growth of a delta (USQRG:55,2,1; USQRG:57,1,1)
1003. progression of delta deposits in a core sample, according to Walther’s law

delta‐plain, delta‐front, and prodelta (USQRG:55,2,1)
1004. the Mississippi River’s final destination

Gulf of Mexico (USQRG:55,2,2)
1005. Why does the Mississippi River delta spread far out into the sea?

The area is protected from strong wave action. (USQRG:55,2,2)
1006. river‐dominated delta

delta constructed from river‐borne sediment, not forces of the sea (USQRG:55,2,2)
1007. active lobe of a delta

portion of the delta that is growing (USQRG:55,2,2)
1008. location of distributary channels in a river‐dominated delta

the active lobe (USQRG:55,2,2)
1009. dating method used for previously active lobes of the Mississippi River delta

carbon‐14 dating (USQRG:55,2,2)
1010. another name for delta lobe growth

depositional activity (USQRG:55,2,2)
1011. How do sediments in an abandoned delta lobe change over time?

compact under their own weight (USQRG:55,2,3)
1012. Why are delta structures always sinking?

isostatic response of the crust to the constantly increasing mass of sediment (USQRG:55,2,3)
1013. location at which young delta lobes form

atop abandoned delta lobes (USQRG:55,2,3)
1014. superimposition

layering of one delta lobe over another previously formed (USQRG:55,2,4)
1015. difficulty of erosion of previously constructed delta lobes

easy (USQRG:55,2,4)
1016. two valuable commodities found in the porous sand of the upper parts of some deltaic cycles

petroleum and natural gas (USQRG:55,2,4)
1017. two factors affecting the size of a delta lobe

rate of sinkage and supply of sediment (USQRG:55,2,5)
1018. current rate of growth of the Mississippi River delta

rapid shrinkage (USQRG:56,1,0)
1019. two events that have reduced the rate of sediment deposition in the Mississippi River delta

construction of levees on the Mississippi and dams on its tributaries (USQRG:56,1,0)
1020. How many times higher is the rate of subsidence in the Mississippi River delta due to removal of groundwater for human use?

5 (USQRG:56,1,0)
1021. number of square miles of the Louisiana coast lost every year

approximately 40 (USQRG:56,2,0)
1022. location of the United States’ largest waterfowl population

the Mississippi River delta (USQRG:56,2,0)
1023. effect of the Gulf of Mexico on the Mississippi River delta

increasing encroachment on the delta (USQRG:56,2,0)
1024. percentage of the annual United States seafood harvest supplied by the Mississippi River delta

nearly 30% (USQRG:56,2,0)
1025. barrier islands

land masses that border long stretches of shoreline without large river deltas (USQRG:56,2,1)
1026. main component of barrier islands

clean sand (USQRG:56,2,1)
1027. Where is the sand that forms barrier islands derived from?

the sea (USQRG:56,2,1)
1028. longshore currents

shallow currents that flow along the coast (USQRG:56,2,1)
1029. How are barrier islands formed?

Waves and longshore currents sweep sand parallel to the shoreline. (USQRG:56,2,1)
1030. type of beaches that have barrier islands with nearly horizontal bedding

those washed by breaking waves (USQRG:56,2,1)
1031. type of beaches that have cross‐bedded barrier islands

those with irregular surfaces and that experience periodic change (USQRG:56,2,1)
1032. type of sediment trapped by lagoons

fine‐grained (USQRG:56,2,2)
1033. two materials typically found in lagoon floors

mud and muddy sands (USQRG:56,2,2)
1034. geological feature often constructed by small rivers along the landward margins of lagoons

deltas (USQRG:56,2,2)
1035. barrier island‐lagoon complex

barrier island and the lagoon behind it (USQRG:56,2,2)
1036. geographical feature separating adjacent barrier islands in a chain

tidal channels (USQRG:56,2,3)
1037. type of bedding in tidal deltas

cross‐bedded (USQRG:56,2,3)
1038. tidal flats

depositional environment found along lagoon shores (USQRG:56,2,3)
1039. two main materials that form tidal flats

sand or muddy sand (USQRG:56,2,3)
1040. geological feature that periodically exposes and floods tidal flats

the ocean’s tide (USQRG:56,2,3)
1041. altitude of tidal flats compared to lagoon marshes

much lower (USQRG:56,2,3)
1042. material formed by rapid plant material decomposition

peat (USQRG:56,2,3)
1043. Which deltaic cycle receives the lowest number in a numbering of several superimposed cycles?

the lowest/oldest (USQRG:56,fig)
1044. Why is most of the water in lagoons in moist climates brackish?

Water remains trapped for some time. (USQRG:56,2,4)
1045. factor affecting the salinity of lagoon water

rate of freshwater runoff from land (USQRG:56,2,4)
1046. climate of the lagoon Laguna Madre

warm and arid (USQRG:56,2,4)
1047. state in which the lagoon Laguna Madre is located

Texas (USQRG:56,2,4)
1048. salinity of the lagoon Laguna Madre

hyper‐saline (USQRG:56,2,4)
1049. two reasons for the hyper‐salinity of the lagoon Laguna Madre

little freshwater flow from rivers and a high rate of evaporation (USQRG:56,2,4)
1050. Why are many forms of marine life excluded from lagoons?

abnormal and fluctuating salinity (USQRG:57,1,0)
1051. relative diversity of fossil fauna in ancient sediments of lagoons

sparse (USQRG:57,1,0)
1052. common burrower in ancient lagoons

segmented worms (USQRG:57,1,0)
1053. effect of burrowers on lagoons

mottled sediments devoid of bedding structure (USQRG:57,1,0)
1054. effect of high sedimentation rates on a barrier island‐lagoon complex

progradation (USQRG:57,1,1)
1055. key difference between progradation of a barrier island‐lagoon complex and that of a delta

A barrier island‐lagoon complex takes place along a broad belt of shoreline. (USQRG:57,1,1)
1056. horizontal sequence of depositional environments in a barrier island‐lagoon complex

barrier island, marsh or tidal delta, lagoon, tidal flat, and marsh (USQRG:57,1,1)
1057. process by which the horizontal sequence of a barrier island‐lagoon complex becomes a vertical sequence

progradation (USQRG:57,1,1)
1058. effect of strong tidal currents on open continental shelves with abundant sand

Currents pile sand into large ridges or dune‐like structures. (USQRG:57,2,0)
1059. effect of strong tidal waves on open continental shelves with abundant sand

Sand spreads out into sheets. (USQRG:57,2,0)
1060. tempestites

sandy beds produced by storms (USQRG:57,2,1)
1061. thickness of most tempestites

a few centimeters (USQRG:57,2,1)
1062. two materials that typically accumulated on quiet continental shelves

mud and muddy sand (USQRG:57,2,1)
1063. direction of Wales relative to central England

west (USQRG:57,2,3)
1064. orientation of mid‐Silurian marine invertebrate fossils found in Wales relative to the shoreline then

roughly parallel (USQRG:57,2,3)
1065. Lingula

inarticulate brachiopod genus (USQRG:57,2,3)
1066. amount of species found in mid‐Silurian fossils in Wales

few (USQRG:57,2,3)
1067. type of water found in ancient Wales near the site of mid‐Silurian fossils

brackish (USQRG:57,2,3)
1068. two types of coastal environments tolerated by Lingula today

brackish and of variable salinity (USQRG:57,2,3)
1069. stability of the center and seaward margin of a lagoon, compared to the shoreline

more stable (USQRG:57,2,4)
1070. Why have geologists inferred a barrier island was present in Wales near the findings of mid‐Silurian Lingula?

Fossils of brachiopods adapted to barrier island conditions have been discovered seaward of sandy deposits. (USQRG:57,2,4)
1071. area of lagoon deposits to which trilobites fossils are restricted

finer‐grained sediments far offshore (USQRG:57,2,5)
1072. identifying characteristic of a stable offshore shelf environment

high diversity of species (USQRG:57,2,5)
1073. stabilizing feature of offshore shelf environments

removal from the influence of river water (USQRG:57,2,5)
1074. Why did ancient offshore shelf environments have a low food supply?

far from the algae and primitive plants flourishing in the lagoon (USQRG:58,1,0)
1075. planktonic graptolites

fragile colonial animals (USQRG:58,1,0)
1076. prevailing type of sedimentation in tropical shallow marine settings lacking siliciclastic sediments

carbonate (USQRG:58,2,1)
1077. geological feature often present in tropical shallow marine settings lacking siliciclastic sediments

coral reefs (USQRG:58,2,1)
1078. type of rock in which reefs form their depositional records

limestone (USQRG:58,2,1)
1079. How do reefs form their own depositional records?

secretion of calcium carbonate by reefs’ own organisms (USQRG:58,2,1)
1080. type of water in which modern reefs grow

shallow water with high clarity and normal marine salinity (USQRG:59,1,0)
1081. type of host water for ancient reefs, compared to that for modern reefs

none (USQRG:59,1,0)
1082. substance used in the basic framework of a reef

calcareous skeletons or organisms (USQRG:59,1,1)
1083. primary organism incorporated into a reef’s structure

coral (USQRG:59,1,1)
1084. How is the framework of a reef strengthened?

cementation of organisms that encrust the surface of the reef (USQRG:59,1,1)
1085. main component of carbonate sediment of reefs

skeletons of reef‐dwelling organisms (USQRG:59,1,1)
1086. How does a reef fill its voids during construction?

trapping carbonate sediment in the porous framework (USQRG:59,1,1)
1087. degree of bedding of reef limestone

nonexistent or poorly bedded (USQRG:59,1,1)
1088. valuable commodity often trapped by ancient buried reefs

petroleum (USQRG:59,1,1)
1089. Why do reefs alter nearby patterns of sedimentation?

stand above the surrounding seafloor (USQRG:59,1,2)
1090. position of the leeward side of a reef, relative to the rest of the reef

side nearest the land (USQRG:59,1,2)
1091. geological feature typically on the leeward side of a reef

relatively calm lagoon (USQRG:59,1,2)
1092. reef flat

horizontal upper surface of a reef that can reach close to sea level (USQRG:59,1,2)
1093. structure of a reef below its living surface

limestone core consisting of dead skeletal framework and trapped sediment (USQRG:59,2,0)
1094. talus

pile of rubble in a reef’s limestone core that has fallen from the reef front (USQRG:59,2,0)
1095. effect on reef height, relative to sea level, of rapid sinking of the seafloor around the reef

none, as the reef builds upward rapidly (USQRG:59,2,1)
1096. two basic structural features of modern reefs

seaward talus deposits and leeward back‐reef strata (USQRG:59,2,1)
1097. time at which the reef flat of a reef growing up to sea level is exposed

low tide (USQRG:59,fig)
1098. two areas near barrier reefs at which sediment accumulates

back‐reef area and in the lagoon (USQRG:59,fig)
1099. patch reefs

isolated reefs formed in lagoons behind elongate reefs (USQRG:59,2,2)
1100. barrier reefs

elongate reefs at the edge of lagoons facing the open sea (USQRG:59,2,2)
1101. fringing reefs

reefs that grow along the coastline without a lagoon behind them (USQRG:59,2,2)
1102. eventual effect of fringing reefs growing seaward

become barrier reefs (USQRG:59,2,2)
1103. atoll

island reefs made of coral (USQRG:59,2,3; USQRG:101,1,8)
1104. two possible atoll shapes

circular or horseshoe‐shaped (USQRG:59,2,3)
1105. geological location at which atolls form

volcanic islands (USQRG:59,2,3)
1106. region known for its atolls

tropical Pacific (USQRG:60,1,0)
1107. scientist who developed the modern explanation for Pacific atolls

Charles Darwin (USQRG:60,1,0)
1108. first stage in the development of a Pacific atoll

volcano rises from the ocean floor (USQRG:60,fig; USQRG:60,1,0)
1109. second stage in the development of a Pacific atoll

fringing reef colonizes an extinct volcano (USQRG:60,fig; USQRG:60,1,0)
1110. third stage in the development of a Pacific atoll

island begins sinking, the fringing reef becomes a barrier reef, and a lagoon forms in the center (USQRG:60,fig; USQRG:60,1,0)
1111. final stage in the development of a Pacific atoll

island sinks completely, leaving a circular reef (USQRG:60,fig; USQRG:60,1,0)
1112. type of stone that accumulates in the central lagoon of an atoll

limestone (USQRG:60,1,0)
1113. side of a horseshoe‐shaped atoll broken the most often

leeward (USQRG:60,2,0)
1114. maximum diameter of horseshoe‐shaped atolls

approximately 40 miles (USQRG:60,2,0)
1115. function of atolls’ lagoons during World War II

natural harbors for ships (USQRG:60,2,0)
1116. How can ancient atolls lying beneath younger sediments be identified?

studying cores of rock brought up from drilling operations (USQRG:60,2,1)
1117. carbonate platform

broad calcium carbonate structure rising above the seafloor on at least one side (USQRG:60,2,2)
1118. Why do organic reefs often grow near carbonate platforms?

Windward margins contain abundant food sources. (USQRG:60,2,2)
1119. type of water body from which calcium carbonate in carbonate platforms precipitates

shallow tropical waters near the site of accumulation (USQRG:60,2,2)
1120. solubility of carbon dioxide in cold water compared to that in warm water

more soluble (USQRG:60,2,3)
1121. chemical formula of carbonic acid

H2CO3 (USQRG:60,2,3)
1122. two compounds that react to form carbonic acid

carbon dioxide (CO2) and water (H2O) (USQRG:60,2,3)
1123. relationship between temperature of seawater and the concentration of carbonic acid

the warmer the water, the lower the concentration of carbonic acid (USQRG:60,2,4)
1124. chemical formula of calcium carbonate

CaCO3 (USQRG:60,2,5)
1125. chemical formula of a calcium ion

Ca2+ (USQRG:60,2,5)
1126. chemical formula of a bicarbonate ion

HCO3‐ (USQRG:60,2,5)
1127. chemical equation of the process of calcium carbonate being broken down by carbonic acid

H2CO3 + CaCO3 = Ca2+ + 2HCO3‐ (USQRG:60,2,5)
1128. relationship between carbonic acid concentration in seawater and precipitation of calcium carbonate

lower the concentration of carbonic acid, the higher the precipitation (USQRG:60,2,6)
1129. level of carbonic acid in warm tropical seas favoring organic reef growth

low (USQRG:60,2,6)
1130. coast of the United States that once housed carbonate platforms

eastern (USQRG:60,2,7)
1131. Why are carbonate platforms geographically restricted today?

coolness of Earth’s climate compared to much of history (USQRG:60,2,7)
1132. peninsula in the western Atlantic and Caribbean region that houses a large carbonate platform

Yucatan (USQRG:60,2,7)
1133. island chain in the western Atlantic and Caribbean region bordered by small carbonate platforms

Antilles (USQRG:60,2,7)
1134. two carbonate platforms that border Florida

Little Bahama Bank and Great Bahama Bank (USQRG:61,1,0)
1135. number of years ago the mid‐Jurassic time period occurred

170 million (USQRG:61,1,1)
1136. length of carbonates that have accumulated on the Bahama banks and in southern Florida since mid‐Jurassic times

10 kilometers (USQRG:61,1,1)
1137. last time period in which the Bahama banks and southern Florida were part of the same carbonate platform

Cretaceous (USQRG:61,1,1)
1138. distance below sea level some shallow‐water Jurassic deposits now lie near southern Florida

10 kilometers (USQRG:61,1,1)
1139. main component of oolites

ooliths (USQRG:61,1,2)
1140. ooliths

spherical grains consisting of aragonite needles precipitated from seawater (USQRG:61,1,2)
1141. geological feature that piles ooliths into shoals

strong currents (USQRG:61,1,2)
1142. type of bedding of oolith shoals in the Bahama banks

cross‐bedding (USQRG:61,1,2)
1143. condition for individual ooliths to form

ability for the ooliths to roll around (USQRG:61,1,2)
1144. stromatolites

layered structures built up over a long time by cyanobacteria (USQRG:61,2,1; USQRG:103,1,12)
1145. How do cyanobacteria form sticky mats?

trapping carbonate mud (USQRG:61,2,1)
1146. action of cyanobacteria after forming a stromatolite layer

growing up through it (USQRG:61,2,1)
1147. time span of the fossil record of stromatolites

3 billion years (USQRG:61,2,1)
1148. two types of environments in which stromatolites are almost exclusively found

supratidal and high intertidal (USQRG:61,2,2)
1149. three characteristics of settings in which stromatolites are almost exclusively found

above sea level most of the time, hot, and dry (USQRG:61,2,2)
1150. two events that usually occur after an underwater cyanobacteria mat is formed

Grazing marine animals eat it or burrowers damage it. (USQRG:61,2,2)
1151. What feature allows large column‐shaped stromatolites to grow in some subtidal channels in the Bahamas?

very strong currents (USQRG:61,2,2)
1152. country in which Shark Bay is located

Australia (USQRG:61,2,2)
1153. two features of Shark Bay that make it conducive to stromatolites

hypersaline waters and few animals (USQRG:61,2,2)
1154. land feature that mudcracks on coastal sands resemble

mudcracks in a mud puddle that has dried up (USQRG:61,2,3)
1155. two types of environments indicated by mudcracks in ancient marine deposits

intertidal or supratidal (USQRG:61,2,3)
1156. approximate time period that geologists recognized turbidity currents had produced certain sedimentary rocks

mid‐20th century (USQRG:61,2,4)
1157. turbidity current

flow of dense, sediment‐charged water moving down a slope due to gravity (USQRG:61,2,4)
1158. geological feature in which turbidity currents were first noticed

clear lakes (USQRG:61,2,5)
1159. From where are turbidity currents in clear lakes formed?

muddy river water hugging the lake floor (USQRG:61,2,5)
1160. Philip Kuenen’s home country

the Netherlands (USQRG:62,1,0)
1161. decade in which Philip Kuenen demonstrated turbidity currents can attain great speeds

the 1930s (USQRG:62,1,0)
1162. two characteristics that help turbidity currents gain speed

being heavily laden with sediment and moving down steep slopes (USQRG:62,1,0)
1163. maximum percentage increase in the density of turbidity currents due to the presence of sediment

100% (USQRG:62,1,0)
1164. behavior of sediment suspended in a turbidity current

act as part of the moving fluid (USQRG:62,1,0)
1165. effect of a flattening slope on a turbidity current

slows and spreads (USQRG:62,1,1)
1166. type of sedimentary bed deposited by turbidity currents

graded (USQRG:62,1,1)
1167. two types of materials found on the bottom of sedimentary beds deposited by turbidity currents

poorly sorted sand and granules (USQRG:62,1,1)
1168. turbidite

graded bed deposited by a slowing turbidity current (USQRG:62,1,1)
1169. continental slope

steeply sloped zone between the continental shelf and the ocean depths (USQRG:62,1,2; USQRG:101,2,1)
1170. two locations at which turbidity currents flowing down continental slopes deposit turbidites

along continental rises and on the abyssal plain (USQRG:62,1,2)
1171. consequence of turbidity currents originating near the continental shelf

erosion of the continental slope and part of the continental rise (USQRG:62,1,2)
1172. feature formed by turbidity currents at the mouths of submarine canyons

deep‐sea fans (USQRG:62,1,2)
1173. geological feature superficially resembling deep‐sea fans formed by turbidity currents

alluvial fans (USQRG:62,1,2)
1174. type of rock most commonly found in the sandy portion of lithified turbidites

greywacke (USQRG:62,1,4)
1175. typical thickness of a single turbidite

a few centimeters (USQRG:62,1,4)
1176. maximum thickness of a single turbidite

1 meter (USQRG:62,1,4)
1177. minimum thickness of a meandering‐river cycle

2 or 3 meters (USQRG:62,1,4)
1178. Why is the base of a turbidite commonly irregular?

The depressions in the sedimentary surface laid down earlier are filled in by the first sediments to settle. (USQRG:62,1,4)
1179. “sole marks”

irregularities in the base of a lithified turbidite (USQRG:62,1,4)
1180. information about turbidity currents that sole marks reveal

direction of water flow (USQRG:62,1,4)
1181. typical rate of sediment accumulation in the abyssal plain

one millimeter per 1,000 years (USQRG:62,2,1)
1182. material that forms most sediment in the deep ocean

clay (USQRG:62,2,1)
1183. two sources of clay in the deep ocean

weathering of rocks from oceanic volcanoes and settling from the water above (USQRG:62,2,1)
1184. ocean with the most abundant supplies of clay due to the weathering of rocks from oceanic volcanoes

Pacific (USQRG:62,2,1)
1185. pelagic sediment

fine‐grained sediment that settles to the deep‐sea floor (USQRG:62,2,1)
1186. pelagic forms of life

organisms occupying the water just above the deep‐sea floor (USQRG:62,2,1)
1187. two biologically produced sediments found on the deep‐sea floor

calcium carbonate and silica (USQRG:62,2,2)
1188. calcareous ooze

calcium carbonate sediment consisting of skeletons of single‐celled planktonic organisms (USQRG:62,2,2)
1189. relative grain size of calcareous ooze

fine (USQRG:62,2,3)
1190. foraminifera

amoeba‐like protozoans whose skeletons form calcareous ooze (USQRG:62,2,3)
1191. nannoplankton

single‐celled floating algae that helps form tropical phytoplankton (USQRG:62,2,3)
1192. maximum depth of calcareous ooze

approximately 4,000 meters (USQRG:62,2,4)
1193. Why does calcareous ooze not exist at depths of 8,000 meters?

dissolves at great depths (USQRG:62,2,4)
1194. Why is carbonic acid more concentrated in ocean depths?

temperature decreases, increasing the concentration level of carbon dioxide and thus carbonic acid (USQRG:62,2,4)
1195. siliceous ooze

biologically formed silica sediment carpeting the ocean floor in certain regions (USQRG:62,2,5)
1196. two regions with siliceous ooze covering the deep‐sea floor

those at high latitude and in the tropical Pacific (USQRG:62,2,5)
1197. two organisms that form siliceous ooze

diatoms and radiolarians (USQRG:62,2,5)
1198. diatoms

highly productive phytoplankton group found in non‐tropical waters (USQRG:62,2,5)
1199. radiolarians

single‐celled planktonic protozoans related to foraminifera (USQRG:62,2,5)
1200. type of silica forming the skeletons of diatoms

opal (USQRG:62,2,5)
1201. Why is it impossible to discern individual skeletons of diatoms and radiolarians?

Opal tends to recrystallize. (USQRG:63,1,0)
1202. diatomaceous earth

soft sediment that forms siliceous ooze before recrystallization (USQRG:63,1,0)
1203. substance found on ocean floors that is used as the abrasive in many scouring powders

diatomaceous earth (USQRG:63,1,0)
1204. geological period in which diatoms first formed

Mesozoic (USQRG:63,1,1)
1205. Why has the composition of pelagic sediments changed markedly through the course of history?

Sediment‐contributing organisms have evolved and gone extinct. (USQRG:63,1,1)
1206. annual monetary cost of landslides in the United States

1.5 billion (USQRG:63,1,2)
1207. deaths caused annually by landslides in the United States

25 to 50 (USQRG:63,1,2)
1208. type of damage that comprises most of the economic cost of landslides

road (USQRG:63,1,2)
1209. maximum potential death toll of a landslide

hundreds of thousands (USQRG:63,1,2)
1210. How can geologists minimize the economic and human costs of landslides?

identifying geologically unstable areas that should be avoided or properly engineered (USQRG:63,1,2)
1211. five indications of geological instability

recent landslides, clay‐rich soils, planes of weakness in rocks, frequent earthquakes, and slope undercutting (USQRG:63,1,2)
1212. example of poor engineering exacerbating natural vulnerability to a landslide

oversteepening a slope (USQRG:63,1,2)
1213. landslide

earth materials moving rapidly under gravitational force (USQRG:63,2,1; USQRG:102,1,14)
1214. two types of movement typically involved in a landslide

downward and lateral (USQRG:63,2,1)
1215. avalanche

movement of snow and ice that is similar to a landslide (USQRG:63,2,1)
1216. number of lives lost annually to avalanches in the United States

approximately 20 (USQRG:63,2,1)
1217. two factors that make downslope movement of soil and rock inevitable

constant stress of gravity and gradual weakening of earth materials through weathering (USQRG:63,2,2)
1218. criteria for a downslope movement of material to be classified as “hazardous”

likely to threaten man‐made structures (USQRG:63,2,2)
1219. smallest volume of material that can be involved in a landslide

1 boulder (USQRG:63,2,2)
1220. country in which the largest landslide on earth occurred prehistorically

Iran (USQRG:63,2,2)
1221. dimensions of the largest landslide on earth

14 kilometers wide by 19 kilometers long (USQRG:63,2,2)
1222. annual monetary cost of landslide damage to buildings and building sites in the United States

approximately $500 million (USQRG:63,2,3)
1223. major California city near which Big Rock Mesa is located

Malibu (USQRG:63,2,3)
1224. number of people killed annually in the United States by small flows and landslides

approximately 25 (USQRG:63,2,4)
1225. number of people killed annually worldwide by landslides

600 (USQRG:63,2,4)
1226. state in which the Kootenai River Valley is located

Montana (USQRG:64,1,2)
1227. dam near the Kootenai River Valley whose construction started in 1967

Libby (USQRG:64,1,2)
1228. major city near the Pierre Formation in the United States

Denver, Colorado (USQRG:64,1,2)
1229. equipment needed to detect old landslides with the potential to reoccur

aerial photography equipment with remote sensing techniques (USQRG:64,1,2)
1230. particular type of clay whose presence indicates natural instability

swelling (USQRG:64,1,3)
1231. season in which movement of soil rich in silt‐to‐clay‐sized material occurs

spring (USQRG:64,1,3)
1232. loess soil

fine soil developed on fine wind‐blown material (USQRG:64,1,3)
1233. city in which 200,000 lives were lost in 1920 during a loess landslide

Kansu, China (USQRG:64,1,3)
1234. event that destroyed the Roman city of Herculaneum in 79AD

mudflow (USQRG:64,1,3)
1235. mountain overlooking the ancient city of Herculaneum

Mount Vesuvius (USQRG:64,1,3)
1236. two formations notorious for landslides triggered by flowage during liquefaction

Rissa Clay in Norway and Leda Clay in Ontario, Canada (USQRG:64,1,3)
1237. general time period in which the Rissa Clay and Leda Clay formations were deposited

late glacial periods (USQRG:64,1,3)
1238. orientation of planes of weakness in bedrock that indicates instability

downslope (USQRG:64,1,4)
1239. schistosity

platy and rod‐shaped minerals in metamorphic rocks (USQRG:64,1,4)
1240. joint orientation relative to slope direction that is vulnerable to landslides

parallel (USQRG:64,1,4)
1241. state in which the Gros Ventre landslide occurred

Wyoming (USQRG:64,1,4)
1242. South Dakota city near a Cretaceous landslide triggered by a plane weakness that dipped steeply downslope

Rapid City (USQRG:64,1,4)
1243. country of the Vaiont Reservoir landslide

Italy (USQRG:64,2,0)
1244. year in which the Vaiont Reservoir landslide occurred

1963 (USQRG:64,2,1)
1245. immediate result of the 1963 landslide plunging into the Vaiont Reservoir

a 300‐foot high wave (USQRG:64,2,1)
1246. number of deaths that occurred in the Vaiont Reservoir landslide

3,000 (USQRG:64,2,1)
1247. four geological features near which landslides are particularly common

stream banks, reservoir shorelines, large lakes, and seacoasts (USQRG:64,2,2)
1248. location that exemplifies of soft glacial sediment and slope undercutting

shores of the Great Lakes (USQRG:64,2,2)
1249. state in which the 1959 Madison Canyon landslide occurred

Montana (USQRG:64,2,3)
1250. event that triggered a 1965 British Columbia landslide that covered Highway 3 with 130 million tons of debris

two small earthquakes (USQRG:64,2,3)
1251. 1965 British Columbia landslide that covered Highway 3 with 130 million tons of debris

Hope Mountain slide (USQRG:64,2,3)
1252. event that triggered a Brazil landslide that killed 600 people in 1967

a three‐hour cloudburst (USQRG:64,2,4)
1253. two events in the southern and central Appalachian Mountains that often coincide with increased landslides

severe local summer cloudbursts and thunderstorms (USQRG:64,2,4)
1254. two geological events correlated by studies of the Canadian Rockies

rainstorms and rockfalls (USQRG:64,2,4)
1255. type of season in which landslides are particularly abundant along the West Coast of North America

rainy (USQRG:64,2,4)
1256. angle of repose

maximum angle that can be measured on a slope when material is stable and at rest (USQRG:65,1,2)
1257. natural angle of repose of stable materials

approximately 40° (USQRG:65,2,0)
1258. location of a 1966 flow of fine‐grained mine waste that killed 144 people

Aberfan, Wales (USQRG:65,2,0)
1259. state in which a failed dam made up of coal mine wastes triggered a 1972 landslide

West Virginia (USQRG:65,2,0)
1260. immediate result of the flow of coal mine wastes caused by a failed dam in 1972 in Buffalo Hollow

a 15‐foot high wave entering Buffalo Creek Valley (USQRG:65,2,1)
1261. type of site in which landfills piled near their angle of repose present safety risks

those subject to earthquake tremors (USQRG:65,2,1)
1262. What action at the base of a slope can set the whole slope in motion?

removal of material (USQRG:65,2,2)
1263. 2006 landslide that blocked California Highway 140 near the Merced River

Ferguson Slide (USQRG:65,fig)
1264. three ways in which humans may load an unstable slope from above

construction of a building, storage tank, or highway on materials that cannot bear the additional load (USQRG:66,1,0)
1265. range of seasonal water level variations in flood‐control reservoirs in steep valleys

more than 100 feet (USQRG:66,1,2)
1266. season in which flood‐control reservoirs in steep valleys lower quickly

spring (USQRG:66,1,2)
1267. mass wasting

downslope movement of materials (USQRG:66,2,1)
1268. the most prevalent geologic process

mass wasting (USQRG:66,2,1)
1269. creep (geologic process)

mass wasting that is too slow to be detected by direct observation (USQRG:66,2,1)
1270. three manifestations of creep

misaligned utility poles, out‐of‐plumb houses, and bulges in stone retainer walls (USQRG:66,2,1)
1271. analogy used by Nuhfer to illustrate the process of mass wasting and creep

melting of a snowman (USQRG:67,1,0)
1272. Why do more landslides occur in spring?

Soils are wet from recently melted snow. (USQRG:67,1,1)
1273. method of determining the likelihood of landslides in areas prone to landslide‐triggering earthquakes and storms

mapping the geological conditions that make an area prone to movement (USQRG:67,1,2)
1274. four groups of people helped by maps of geological conditions that make an area prone to landslides

planners, lenders, homeowners, and insurers (USQRG:67,1,2)
1275. maximum speed of massive landslides

upwards of 100 miles per hour (USQRG:67,1,3)
1276. most infrequent type of land‐wasting events

massive landslides involving hundreds of tons of material (USQRG:67,1,3)
1277. For what TWO reasons should the 1963 Vaiont Reservoir landslide have been anticipated?

The valley contained multiple landslide scars and the geological conditions indicated the likelihood of massive failures. (USQRG:67,1,3)
1278. sturzstorm

landslide involving billions of cubic yards of material (USQRG:67,1,4)
1279. California region with evidence of a sturzstorm

Shasta (USQRG:67,1,4)
1280. planet that contains evidence of sturzstorms

Mars (USQRG:67,1,4)
1281. three indicators of mass wasting over a long time period

gradual movement as creep, seasonally increased landslide activity, and irregular rainstorm or earthquake‐triggered landslides (USQRG:67,2,0)
1282. relationship between size and frequency of a landslide

the larger the landslide, the more infrequently it occurs (USQRG:67,2,0)
1283. two factors that increase the need for a complete geologic investigation of an area

susceptibility to landslides and encroachment by humans (USQRG:67,2,1)
1284. criterion that should mandate a complete geologic investigation of an area, according to Nuhfer

a structure whose failure may endanger human lives (USQRG:67,2,1)
1285. three topographic features examined during a complete geologic investigation of an area

relief, steepness, and shape of slope (USQRG:67,2,3)
1286. two bedrock features examined during a complete geologic investigation of an area

types and conditions of bedrock underlying the slope (USQRG:67,2,4)
1287. two soil features examined during a complete geologic investigation of an area

type and thickness (USQRG:67,2,5)
1288. two features of bedding planes or rock fabric examined during a complete geologic investigation of an area

angle and direction (USQRG:67,2,6)
1289. four features of discontinuities examined during a complete geologic investigation of an area

frequency, direction, extent, and type of infilling material present (USQRG:67,2,7)
1290. two vegetation features examined during a complete geologic investigation of an area

amount and types present on the slope (USQRG:67,2,8)
1291. two aspects of moisture examined during a complete geologic investigation of an area

sources of moisture and moisture‐retaining properties of the earth materials (USQRG:67,2,9)
1292. three types of drainage examined during a complete geologic investigation of an area

surface, subsurface, and any human‐made drainage (USQRG:67,2,10)
1293. four events whose past occurrences are traced during a complete geologic investigation of an area

earthquakes, slides, flows, and rockfalls (USQRG:67,2,11; USQRG:67,2,12)
1294. three features of materials susceptible to failure examined during a complete geologic investigation of an area

volume of such materials, ways in which they may fail, and area that may be affected by such a failure (USQRG:67,2,13)
1295. three roles of geologists at the regional level

data gatherers, compilers, and organizers of basic information (USQRG:67,2,14)
1296. federal government body in charge of geological surveys

U.S. Government Survey (USQRG:67,2,14)
1297. job scope of geologists employed by state geological surveys

construct geological and slope stability maps (USQRG:67,2,14)
1298. main source of information for mapping completed by geologists

field study of soils and rock formations (USQRG:67,2,14)
1299. two types of remote sensing photography that aid geologists in mapping

satellite and high‐altitude (USQRG:68,1,0)
1300. factor of safety

quantitative estimation of slope safety (USQRG:68,1,1)
1301. prerequisite of most engineering design projects involving construction on a sloping terrain

calculating of a factor of safety (USQRG:68,1,1)
1302. two professions that make use of slope stability research

mining and civil engineering (USQRG:68,1,1)
1303. country supporting a vigorous research program studying massive earth movements

Russia (USQRG:68,1,2)
1304. How does the use of computers affect factor of safety calculations?

faster and less tedious results (USQRG:68,1,3)
1305. science most essential to understanding good land use, according to Nuhfer

geology (USQRG:68,1,5)
1306. Why should citizens understand slope hazards, according to Nuhfer?

Many homes and developments are built on slopes. (USQRG:68,1,5)
1307. fraction of civil engineers who take at least one geology course before graduation

one‐half (USQRG:68,2,0)
1308. year in which one of the most expansive landslides in history occurred near Thistle, Utah

1983 (USQRG:68,2,1)
1309. cost of the relocation of a major highway and railroad near Thistle, Utah, after a major landslide occurred

$200 million (USQRG:68,2,1)
1310. newspaper whose reporter coined the term Dust Bowl

Washington Evening Star (USQRG:68,2,2)
1311. total cultivated land in the United States in the 1930s, in acres

530 million (USQRG:68,2,3)
1312. type of crop most prevalent in the Great Plains in the 1930s

cereal (USQRG:68,2,3)
1313. summer fallow

only planting on cultivated land on alternate seasons (USQRG:68,2,3)
1314. fallow period

time when a plot of land remains uncropped (USQRG:68,2,3)
1315. dust mulching

process in which the soil is frequently clean tilled (USQRG:68,2,3)
1316. three purposes of dust mulching

leave no crop residues on the surface, control weeds, and preserve moisture evaporation (USQRG:68,2,3)
1317. two factors that optimized conditions for wind erosion during the Dust Bowl

frequent cultivation and lack of crop canopy and residues (USQRG:68,2,3)
1318. two materials that are removed from topsoil during wind erosion

silt and clay (USQRG:68,2,4)
1319. four states hit hardest by wind erosion during the Dust Bowl

Texas, Oklahoma, Colorado, and Kansas (USQRG:69,1,1)
1320. westernmost state majorly affected by Dust Bowl wind erosion

Montana (USQRG:69,1,1)
1321. group of Canadian provinces affected by the Dust Bowl wind erosion

Canadian Prairie Provinces (USQRG:69,1,1)
1322. How did the Dust Bowl wind erosion make travel difficult?

Airborne dust reduced visibility. (USQRG:69,1,1)
1323. general maximum amount of topsoil removed from some places during the Dust Bowl

3 to 4 inches (USQRG:69,1,2)
1324. maximum height of dunes formed by topsoil during the Dust Bowl

15 to 20 feet (USQRG:69,1,2)
1325. percentage of land affected by wind erosion in a Soil Conservation Service survey of 20 Dust Bowl counties

80 (USQRG:69,2,0)
1326. percentage of land seriously affected by wind erosion in a Soil Conservation Service survey of 20 Dust Bowl counties

40 (USQRG:69,2,0)
1327. event that caused the disappearance of many small Great Plain towns and community institutions during the Dust Bowl

mass migration (USQRG:69,2,1)
1328. three examples of non‐detrimental tillage and agricultural management practices

use of windbreaks, maintenance of surface crop residues, use of better machinery (USQRG:70,1,0)
1329. three methods of conservation tillage

stubble mulch, mulch, and residue tillage (USQRG:70,1,0)
1330. crops used in a three‐year agricultural rotation

wheat and sorghum (USQRG:70,1,0)
1331. areas in which a three‐year agricultural rotation is especially common

humid regions in the West (USQRG:70,1,0)
1332. four states in 1982 with the most serious erosion per unit area

Texas, Colorado, Nevada, and Montana (USQRG:70,1,1)
1333. three geological features that plagued the United States during the 1930s

strong winds, drought, and clouds of dust (USQRG:70,1,2)
1334. percentage of the United States affected by the Dust Bowl

nearly 75% (USQRG:70,1,2)
1335. Dust Bowl

area of the Great Plains where drought and inappropriate farming practices resulted in severe soil erosion in the 1930s (USQRG:70,2,0; USQRG:102,2,12)
1336. time period in which the seeds of the Dust Bowl were sown, according to Colenso

early 1920s (USQRG:70,2,2)
1337. event that led farmers to try new mechanized farming techniques in the years before the Dust Bowl

post‐World War I recession (USQRG:70,2,2)
1338. total area of United States farmland that was plowed for the first time between 1925 and 1930

5 million acres (USQRG:70,2,2)
1339. size of the 1931 United States crop compared to that of previous years

record high (USQRG:70,2,2)
1340. two factors that severely depressed wheat prices in the early 1930s United States

the Great Depression and overproduction of wheat (USQRG:70,2,2)
1341. What event occurs if plow‐based farming is implemented in prairies?

erosion of topsoil (USQRG:70,2,2)
1342. two characteristics of land without topsoil

vulnerable to drought and inhospitable for growing crops (USQRG:70,2,3)
1343. black blizzards

dust storms occurring in the Dust Bowl caused by drought and the loss of topsoil (USQRG:70,2,3)
1344. number of black blizzards reported in 1932

14 (USQRG:70,2,3)
1345. number of black blizzards reported in 1933

40 (USQRG:70,2,3)
1346. year the Dust Bowl ended due to the end of drought

1939 (USQRG:70,2,4)
1347. tilling

turning over the top layer of soil or removing weeds and adding fertilizers and pesticides (USQRG:70,1,3)
1348. soil nutrient that escapes topsoil during tilling

carbon dioxide (USQRG:70,1,3)
1349. no‐till

sustainable farming method that keeps nutrients in the soil (USQRG:70,1,3)
1350. location of organic matter in topsoil farmed with no‐till

at the surface (USQRG:70,1,3)
1351. two processes reduced by the presence of healthy topsoil

water runoff and erosion (USQRG:70,1,3)
1352. Okies

nickname given to poor migrants from the Southwestern United States during the Dust Bowl (USQRG:71,1,1)
1353. percentage of Okies that actually came from Oklahoma

approximately 20% (USQRG:71,1,1)
1354. fraction of Great Plains farmers who left their homes during the Dust Bowl

one‐third (USQRG:71,1,1)
1355. state to which most migrating farmers during the Dust Bowl moved

California (USQRG:71,1,1)
1356. United States president during the Great Depression and Dust Bowl

Franklin D. Roosevelt (USQRG:71,1,3)
1357. year in which the first mortgage and farming relief act was passed under the New Deal

1933 (USQRG:71,1,3)
1358. purpose of the first mortgage and farming relief act of the New Deal

reduce foreclosures and keep farms afloat (USQRG:71,2,0)
1359. number of acres of United States farmland ruined by the end of 1934

approximately 35 million (USQRG:71,2,0)
1360. number of acres of topsoil that had blown away in the United States by the end of 1934

approximately 100 million (USQRG:71,2,0)
1361. purpose of the 1934 Taylor Grazing Act

designated 140 million acres as protected federal land (USQRG:71,2,1)
1362. two activities monitored on federal lands under the Taylor Grazing Act

grazing and planting (USQRG:71,2,1)
1363. New Deal program known as the CCC

Civil Conservation Corps (USQRG:71,2,1)
1364. time period in which the government created the CCC

early 1930s (USQRG:71,2,1)
1365. number of young men who volunteered for work with the CCC

3 million (USQRG:71,2,1)
1366. nickname for CCC workers

Rooseveltʹs ʺForest Armyʺ (USQRG:71,2,1)
1367. three purposes of the CCC’s work

control floods, conserve water, and prevent further soil erosion (USQRG:71,2,1)
1368. period in which the Farm Security Administration, Drought Relief Service, and Resettlement Administration were established

between 1933 and 1935 (USQRG:71,2,2)
1369. New Deal program known as the WPA

Works Progress Administration (USQRG:72,1,1)
1370. act under which the WPA was created

Emergency Relief Appropriation Act (USQRG:72,1,1)
1371. number of people employed by the WPA

over 8.5 million (USQRG:72,1,1)
1372. work completed by WPA employees

construction of roads, bridges, airports, public parks, and buildings (USQRG:72,1,1)
1373. Black Sunday

day on which million of tons of dirt from the Great Plains blew into Washington, D.C. (USQRG:72,1,2)
1374. government agency once known as the SCS

Soil Conservation Service (USQRG:72,1,2)
1375. federal department that housed the SCS

Department of Agriculture (USQRG:72,1,2)
1376. federal act that established the SCS

Soil Conservation Act (USQRG:72,1,2)
1377. successor of the SCS

Natural Resources Conservation Service (USQRG:72,1,3)
1378. two ideas promoted by the SCS

healthy soil management and farming practices (USQRG:72,1,3)
1379. three SCS farming practices still used today in the Great Plains

irrigation, crop diversity, and no‐till farming (USQRG:72,1,3)
1380. number of hectares of arid land in North America

450 million (USQRG:72,1,4)
1381. percentage of arid land in North America that suffers moderate to severe desertification

90 (USQRG:72,1,4)
1382. city in which NASAʹs Goddard Space Flight Center is located

Greenbelt, Maryland (USQRG:72,1,6)
1383. What method did Siegfried Schubert and his colleagues use to analyze climate over the past century?

a computer model with modern‐era satellite data (USQRG:72,1,6)
1384. surface temperature of the Pacific Ocean relative to its average during the Dust Bowl

cooler (USQRG:72,1,6)
1385. surface temperature of the Atlantic Ocean relative to its temperature during the Dust Bowl

warmer (USQRG:72,1,6)
1386. large body of water with reduced moisture during the Dust Bowl due to abnormal ocean temperatures

Gulf of Mexico (USQRG:72,2,0)
1387. the United Statesʹ major climatic event, according to Siegfried Schubert

the 1930s drought (USQRG:72,2,1)
1388. identifying characteristic of La Niñas

reduced Pacific Ocean surface temperatures (USQRG:72,2,2)
1389. type of conditions created in the Great Plains by La Niñas

dry (USQRG:72,2,2)
1390. atmospheric general circulation model known as NSIPP

NASAʹs Seasonal‐to‐Interannual Prediction Project (USQRG:72,2,3)
1391. two sets of NASA satellite observations used to develop NSIPP

radiation measurements from the Earthʹs Radiant Energy System and precipitation data from the Global Precipitation Climatology Project (USQRG:72,2,3)
1392. jet stream

ribbon of fast moving air near the Earthʹs surface (USQRG:72,2,4)
1393. relative strength of the jet stream during the Dust Bowl

weak (USQRG:72,2,4)
1394. normal direction of travel of the jet stream

westward over the Gulf of Mexico and then northward over the Great Plains (USQRG:72,2,4)
1395. effect of the jet stream’s weakening on its travels

travels farther south (USQRG:73,1,0)
1396. What soil characteristic can localize droughts, as confirmed by Siegfried Schubertʹs study?

moisture levels (USQRG:73,1,1)
1397. type of process in which scarce rain leads to less evaporation, leading to even less rain

feedback (USQRG:73,1,1)
1398. common factor in most major droughts of the United States in the 1900s

cool tropical Pacific (USQRG:73,1,2)
1399. organization that funded Siegfried Schubertʹs study of the American climate over the past century

NASAʹs Earth Science Enterprise (USQRG:73,2,0)
1400. two purposes of the Earth Science Enterprise

understand the Earth as an integrated system and improve climate, weathering, and natural hazard prediction (USQRG:73,2,1)

Author

dog

37809

Card Set

super quiz section 2

Description

super quiz section 2

Updated

2010-09-28T00:59:52Z

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