super quiz section 2

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super quiz section 2
2010-09-27 20:59:52
super quiz section

super quiz section 2
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  1. 457. general location of most early cities and towns
    near streams (USQRG:27,1,1)
  2. 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)
  3. 459. groundwater
    all water contained in spaces within the bedrock and regolith (USQRG:27,1,3)
  4. 460. percentage of Earth’s water that is groundwater
    less than 1% (USQRG:27,1,3)
  5. 461. amount of groundwater on Earth relative to amount of freshwater in lakes and streams
    40 times more (USQRG:27,1,3)
  6. 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)
  7. 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)
  8. 464. origin of most groundwater
    rainfall (USQRG:27,2,1)
  9. 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)
  10. 466. scientist who determined groundwater comes from rainfall
    Pierre Perrault (USQRG:27,2,2)
  11. 467. Pierre Perrault’s occupation
    physicist (USQRG:27,2,2)
  12. 468. In what century was it established that groundwater comes from rain?
    17th century (USQRG:27,2,2)
  13. 469. river that Pierre Perrault used to link rainfall and groundwater
    Seine (USQRG:27,2,2)
  14. 470. factor that needs to be taken into account when comparing amounts of rainfall and stream runoff
    evaporation (USQRG:27,2,2)
  15. 471. What land area has no water underneath it?
    nowhere (USQRG:27,2,3)
  16. 472. depth to which most usable groundwater exists
    750 meters (USQRG:27,2,3)
  17. 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)
  18. 474. greatest depth at which an oil drill found water
    9.4 kilometers (USQRG:27,2,3)
  19. 475. greatest depth at which groundwater has been found
    11 kilometers (USQRG:27,2,3)
  20. 476. location at which groundwater has been found at its great depth
    Kola Peninsula (USQRG:27,2,3)
  21. 477. ethnicity of scientists who discovered groundwater at its greatest known depth
    Russian (USQRG:27,2,3)
  22. 478. first layer of ground passed through when digging a well
    moist soil (USQRG:28,1,0)
  23. 479. second layer of ground passed through when digging a well
    zone of aeration (USQRG:28,1,0)
  24. 480. zone of aeration
    open space in regolith or bedrock mainly filled with air (USQRG:28,1,0)
  25. 481. another name for the zone of aeration
    unsaturated zone (USQRG:28,1,0)
  26. 482. amount of water saturation present in the zone of aeration
    none (USQRG:28,1,0)
  27. 483. third layer of ground passed through when digging a well
    saturated zone (USQRG:28,1,0)
  28. 484. saturated zone
    underground area in which all openings are filled with water (USQRG:28,1,0)
  29. 485. water table
    upper surface of the saturated zone (USQRG:28,1,0)
  30. 486. typical orientation of the water table
    sloping toward the nearest stream or lake (USQRG:28,1,0)
  31. 487. location of the water table in deserts
    far underground (USQRG:28,1,0)
  32. 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)
  33. 489. type of sediment that allows for a fringe on top of the water table
    fine‐grained (USQRG:28,1,1)
  34. 490. maximum thickness of the fringe on top of the water table
    60 centimeters (USQRG:28,1,1)
  35. 491. force that draws ink through blowing paper and kerosene through the wick of a lamp
    capillary attraction (USQRG:28,2,0)
  36. 492. How does the water table appear in humid regions?
    as a “subdued imitation of the land surface above it” (USQRG:28,2,1)
  37. 493. topographical location with the lowest pressure on the water table
    low points, such as valleys (USQRG:28,2,1)
  38. 494. type of area to which water in the water table tends to move
    low points (USQRG:28,2,1)
  39. 495. event that would occur in the water table if all rainfall ceased
    flattening of the water table (USQRG:28,2,1)
  40. 496. level that the water table would reach if all rainfall ceased
    level of the water table in valleys (USQRG:28,2,1)
  41. 497. How are changes in the water table manifested above ground during droughts?
    drying up of wells (USQRG:28,2,1)
  42. 498. How does water seepage into the ground change if all rainfall ceases?
    diminishes and then stops altogether (USQRG:28,2,1)
  43. 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)
  44. 500. three geological features that result from the water table intersecting the land surface
    lakes, marshes, and streams (USQRG:28,fig)
  45. 501. How is the water table maintained at a normal level?
    repeated rainfall (USQRG:28,2,1)
  46. 502. substance that forms a layer coinciding with surface soil
    moisture (USQRG:28,fig)
  47. 503. upper limit that the water table represents
    all readily usable groundwater (USQRG:29,1,1)
  48. 504. two groups that seek to determine the depth and shape of the water table
    groundwater geologists and well drillers (USQRG:29,1,1)
  49. 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)
  50. 506. two units commonly used to measure groundwater movement
    centimeters per day and meters per year (USQRG:29,1,3)
  51. 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)
  52. 508. porosity
    percentage of the total volume of a rock consisting of open spaces (USQRG:29,1,4; USQRG:103,2,21)
  53. 509. pores
    open spaces in a rock (USQRG:29,1,4)
  54. 510. factor determining the amount of water a given volume of rock or sediment can contain
    porosity (USQRG:29,1,4)
  55. 511. three factors that affect sediments’ porosity
    size, shape, and compactness of particles (USQRG:29,1,5)
  56. 512. maximum porosity of well‐sorted sands and gravels
    approximately 20% (USQRG:29,1,5)
  57. 513. maximum porosity of clay
    approximately 50% (USQRG:29,1,5)
  58. 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)
  59. 515. general porosity of igneous and metamorphic rocks
    low (USQRG:29,1,6)
  60. 516. permeability
    measure of how easily a solid allows fluids to pass through it (USQRG:29,1,7: USQRG:102,2,16)
  61. 517. expected permeability for a rock with very low porosity
    low (USQRG:29,1,7)
  62. 518. force that exists between a solid surface and a film of water
    molecular attraction (USQRG:29,2,0)
  63. 519. relationship between amount of cement present and porosity of a rock
    more cement lowers porosity (USQRG:29,fig)
  64. 520. diameter of clay particles
    less than 0.005 millimeters (USQRG:30,1,0)
  65. 521. permeability level of clay
    low (USQRG:30,1,0)
  66. 522. relationship between pore size and permeability
    smaller pore size lowers permeability (USQRG:30,1,0)
  67. 523. diameter of sand particles
    0.06 to 2 millimeters (USQRG:30,1,1)
  68. 524. relative size of gravel pores
    very large (USQRG:30,1,1)
  69. 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)
  70. 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)
  71. 527. process that resulted in the presence of clay in most soil
    chemical weathering of bedrock (USQRG:30,1,2)
  72. 528. Why is most soil less permeable than its underlying rock?
    presence of fine clay particles (USQRG:30,1,2)
  73. 529. force that keeps some rainwater in topsoil
    molecular attraction (USQRG:30,1,2)
  74. 530. two processes through which the rainwater retained by topsoil returns to the atmosphere
    evaporation and transpiration (USQRG:30,2,0)
  75. 531. force that channels most rainwater to the water table
    gravity (USQRG:30,2,1)
  76. 532. underground zone that is mostly dry between rains
    zone of aeration (USQRG:30,2,1)
  77. 533. percolation (in geology)
    movement of groundwater in the saturated zone (USQRG:30,2,2)
  78. 534. process similar to the flow of water after gently squeezing a saturated sponge
    percolation (USQRG:30,2,2)
  79. 535. type of path by which groundwater moves through small pores during percolation
    parallel and threadlike (USQRG:30,2,2)
  80. 536. Why does percolation stop on the sides of pores in rocks?
    molecular attraction (USQRG:30,2,2)
  81. 537. general direction of groundwater percolation
    toward surface streams and lakes (USQRG:30,2,3)
  82. 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)
  83. 539. force that deep groundwater paths resist to flow into surface streams
    gravity (USQRG:31,1,0)
  84. 540. altitudes at which upward flow of groundwater into streams is possible
    all altitudes (USQRG:31,1,0)
  85. 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)
  86. 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)
  87. 543. recharge (of groundwater)
    replenishment of groundwater through rainfall and snowmelt entering the ground (USQRG:31,1,1)
  88. 544. groundwater recharge areas
    regions of the ground in which precipitation seeps beneath the surface to the saturated zone (USQRG:31,1,1)
  89. 545. groundwater discharge areas
    regions in which subsurface water is discharged to streams, lakes, ponds, or swamps (USQRG:31,1,1)
  90. 546. surface area of groundwater recharge areas compared to that of discharge areas
    larger (USQRG:31,2,0)
  91. 547. speed of groundwater as it moves from recharge to discharge areas
    slow (USQRG:31,1,1)
  92. 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)
  93. 549. the minimum amount of time for water to travel from a recharge area to a discharge area
    several days (USQRG:31,2,1)
  94. 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)
  95. 551. parts of a humid landscape considered recharge areas
    entire landscape beyond streams and their floodplains (USQRG:31,2,2)
  96. 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)
  97. 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)
  98. 554. type of rock strata in which downward and upward percolation is more efficient
    most porous (USQRG:31,fig)
  99. 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)
  100. 556. two common ways people obtain groundwater
    natural springs or excavating wells that reach an underground body of water (USQRG:32,1,1)
  101. 557. frequency of direct recharge in arid regions
    infrequently or minimally (USQRG:32,1,fig)
  102. 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)
  103. 559. spring
    a flow of groundwater emerging naturally at surface level (USQRG:32,1,2)
  104. 560. simplest type of spring
    one that issues at an intersection of the land surface and water table (USQRG:32,1,2)
  105. 561. kinds of rocks in which small springs are found
    all (USQRG:32,1,2)
  106. 562. three most common rocks in which large springs are found
    lava, limestone, and gravel (USQRG:32,1,2)
  107. 563. common reason for the localization of springs
    vertical or horizontal change in permeability (USQRG:32,1,3)
  108. 564. result of a porous limestone layer above an impermeable shale layer at the water table
    a spring (USQRG:32,2,fig)
  109. 565. aquiclude
    layer of impermeable rock adjacent to a permeable layer (USQRG:32,1,3; USQRG:101,1,5)
  110. 566. fault (in geology)
    plane within rocks along which movement has taken place (USQRG:32,1,3; USQRG:101,2,15)
  111. 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)
  112. 568. condition that must be met for a well to supply water
    intersects the water table (USQRG:33,1,1)
  113. 569. rate of withdrawal of water from a new well compared to the rate of local groundwater flow
    greater (USQRG:33,1,2)
  114. 570. effect of water being pumped from a new well
    cone of depression forms around the well (USQRG:33,1,2)
  115. 571. cone of depression
    conical indentation in the water table surrounding a new well after it begins operating (USQRG:33,1,2)
  116. 572. How obvious are cones of depression in most small domestic wells?
    “barely discernible” (USQRG:33,2,0)
  117. 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)
  118. 574. effect on hydraulic gradient once the rate of inflow of a new well matches the rate of withdrawal
    stabilization (USQRG:33,2,0)
  119. 575. effect of the wet season on the rate of groundwater recharge
    increases (USQRG:33,fig)
  120. 576. slope of the hydraulic gradient during the wet season
    relatively steep (USQRG:33,fig)
  121. 577. effect of increased pumping of a well during the dry season on a cone of depression
    increases in size (USQRG:33,fig)
  122. 578. Why are most igneous and metamorphic rocks not very permeable?
    small and constricted mineral grains (USQRG:34,1,0)
  123. 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)
  124. 580. perched water body
    body of water that lies on top of an aquiclude, above the main water table (USQRG:34,1,1)
  125. 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)
  126. 582. aquifer
    body of highly permeable rock lying in the zone of saturation (USQRG:34,1,2)
  127. 583. original language of the word “aquifer”
    Latin (USQRG:34,1,2)
  128. 584. Latin meaning of the word “aquifer”
    water carrier (USQRG:34,1,2)
  129. 585. three rock types that are generally good aquifers
    gravel, sand, and sandstone (USQRG:34,1,2)
  130. 586. material whose presence reduces the quality of sandstone as an aquifer
    cement (USQRG:34,1,2)
  131. 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)
  132. 588. unconfined aquifer
    aquifer in direct contact with the atmosphere (USQRG:34,2,1)
  133. 589. confined aquifer
    aquifer bounded by aquicludes (USQRG:34,2,1)
  134. 590. approximate percentage of groundwater used in irrigation obtained from the High Plains aquifer in the United States
    30 (USQRG:34,2,2)
  135. 591. What type of aquifer is the High Plains aquifer?
    unconfined aquifer (USQRG:34,2,2)
  136. 592. average depth of the High Plains aquifer
    approximately 65 meters (USQRG:34,2,2)
  137. 593. number of wells that tap the High Plains aquifer
    approximately 170,000 wells (USQRG:34,2,2)
  138. 594. two most common types of rocks in the High Plains aquifer
    sandy and gravelly (USQRG:34,2,2)
  139. 595. two geological ages during which most of the rocks in the High Plains aquifer were formed
    Tertiary and Quarternary (USQRG:34,2,2)
  140. 596. average rate of water flow through the High Plains aquifer
    30 centimeters per day (USQRG:34,2,2)
  141. 597. orientation of the water table in the High Plains aquifer
    west to east (USQRG:34,2,2)
  142. 598. Through what two means is the High Plains aquifer recharged?
    direct precipitation and seepage from streams (USQRG:34,2,2)
  143. 599. first decade in which the groundwater High Plains aquifer was tapped for irrigation
    the 1930s (USQRG:34,2,3)
  144. 600. original reason for the High Plains aquifer being used for irrigation
    severe regional droughts (USQRG:34,2,3)
  145. 601. decade of the second peak in demand for irrigation water from the High Plains aquifer
    the 1950s (USQRG:34,2,3)
  146. 602. rate of annual recharge of the High Plains aquifer compared to the rate of water being withdrawn
    much less (USQRG:34,2,3)
  147. 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)
  148. 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)
  149. 605. part of metamorphic and igneous rocks that must be penetrated by a well to produce water
    fractures (USQRG:34,fig)
  150. 606. eight states lying within the High Plains aquifer
    South Dakota, Wyoming, Nebraska, Colorado, Kansas, Oklahoma, New Mexico, and Texas (USQRG:35,fig)
  151. 607. Which state’s land area lies mostly within the High Plains aquifer?
    Nebraska (USQRG:35,fig)
  152. 608. direction of water flow in the High Plains aquifer, in relation to contour lines
    perpendicular (USQRG:35,fig)
  153. 609. three rivers in Wyoming and Nebraska contained within the High Plains aquifer
    North Platte, North Loop, and Elkton (USQRG:35,fig)
  154. 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)
  155. 611. two direct effects of reduced thickness of the saturated zone on aquifers
    decreased water yield and increased pumping costs (USQRG:36,1,0)
  156. 612. home state of the Dakota aquifer
    South Dakota (USQRG:36,1,1)
  157. 613. What type of aquifer is the Dakota aquifer?
    confined (USQRG:36,1,1)
  158. 614. mountain range to the west of the Dakota aquifer
    the Black Hills (USQRG:36,1,1)
  159. 615. two geographical features forming the land surface of the Black Hills
    permeable strata and bounding aquicludes (USQRG:36,1,1)
  160. 616. two types of stone in the aquifer units of the Dakota aquifer
    sandstone and limestone (USQRG:36,fig)
  161. 617. location at which rain must fall to recharge the Dakota aquifer
    permeable units at the surface (USQRG:36,1,1)
  162. 618. role of aquicludes in the Dakota aquifer
    confining units (USQRG:36,fig)
  163. 619. river east of the Black Hills that is part of the Dakota aquifer system
    Missouri (USQRG:36,fig)
  164. 620. uplift portion of the Dakota aquifer system
    Sioux Uplift (USQRG:36,fig)
  165. 621. direction of groundwater flow in the Dakota aquifer
    east (USQRG:36,1,1; USQRG:36,fig)
  166. 622. direction of water flow during percolation into a confined aquifer
    downward (USQRG:36,1,2)
  167. 623. type of pressure that increases as water descends in a confined aquifer
    hydrostatic (USQRG:36,1,2)
  168. 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)
  169. 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)
  170. 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)
  171. 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)
  172. 628. artesian well
    well drilled into an artesian aquifer, allowing water to rise naturally to the surface (USQRG:36,2,0)
  173. 629. artesian spring
    freely flowing spring supplied by an artesian aquifer (USQRG:36,2,0)
  174. 630. city from which the term “artesian” is derived
    Artois, France (USQRG:36,2,0)
  175. 631. Roman name for the city of Artois
    Artesium (USQRG:36,2,0)
  176. 632. Why was the term “artesian” derived from the name of a city?
    Artesian flow was first studied in Artois. (USQRG:36,2,0)
  177. 633. maximum height of a fountain created by artesian water pressure under ideal conditions
    60 meters (USQRG:36,2,0)
  178. 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)
  179. 635. advantage of tapping artesian wells and springs
    avoid the cost of pumping (USQRG:36,2,0)
  180. 636. major source of water in dry regions of western North America
    groundwater (USQRG:37,1,1)
  181. 637. average discharge of aquifer systems in dry regions of western North America
    low (USQRG:37,1,1)
  182. 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)
  183. 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)
  184. 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)
  185. 641. nonrenewable resources
    natural supplies formed only over geologically long intervals of time (USQRG:37,1,1)
  186. 642. three nonrenewable resources being used at unsustainable rates
    petroleum, minerals, and groundwater (USQRG:37,1,1)
  187. 643. time scale needed to restore some aquifers to their original state
    centuries or millennia (USQRG:37,1,1,)
  188. 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)
  189. 645. process that can halt the fall of the water table
    artificial recharge (USQRG:37,2,2)
  190. 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)
  191. 647. type of process that removes pollutants from biodegradable liquid waste as it percolates toward the groundwater
    biological (USQRG:37,2,2)
  192. 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)
  193. 649. injection wells
    wells used to pump groundwater back into the ground after being used for nonpolluting industrial purposes (USQRG:38,1,0)
  194. 650. zone recharged by injection wells
    saturated zone (USQRG:38,1,0)
  195. 651. action that accelerated the tilting of the Leaning Tower of Pisa
    withdrawal of groundwater from aquifers (USQRG:38,2,fig)
  196. 652. country of the Leaning Tower of Pisa
    Italy (USQRG:38,2,fig)
  197. 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)
  198. 654. effect on water pressure of the withdrawal of groundwater from an aquifer
    reduction (USQRG:38,1,1)
  199. 655. effect on aquifer particles of the withdrawal of groundwater from an aquifer
    slight shifting (USQRG:38,1,1)
  200. 656. effect on the land surface particles of the withdrawal of groundwater from an aquifer
    subsiding (USQRG:38,1,1)
  201. 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)
  202. 658. region of the United States with widespread land subsidence due to withdrawal of groundwater
    southwestern (USQRG:38,1,1)
  203. 659. effect on land subsidence in areas subject to flooding in the United States
    increase (USQRG:38,1,1)
  204. 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)
  205. 661. ancient Aztec capital
    Tenochtitlan (USQRG:38,1,2)
  206. 662. modern‐day city on top of the ancient Aztec capital Tenochtitlan
    Mexico City (USQRG:38,1,2)
  207. 663. unique geographic feature of the ancient Aztec capital
    situated in the middle of a shallow lake (USQRG:38,1,2)
  208. 664. effect of rapid withdrawal of groundwater around Mexico City on porous lake sediments
    compression (USQRG:38,1,2)
  209. 665. year in which construction on the Leaning Tower of Pisa began
    1174 (USQRG:38,1,2)
  210. 666. type of sediments on which the Leaning Tower of Pisa was built
    unstable fine‐grained floodplain (USQRG:38,1,2)
  211. 667. century in which the tilting of the Leaning Tower of Pisa rapidly increased
    20th (USQRG:38,1,2)
  212. 668. recent improvement to the Leaning Tower of Pisa to keep it stable
    strengthening of the foundation (USQRG:38,1,2)
  213. 669. action necessary to keep the Leaning Tower of Pisa stable
    strict controls on the withdrawal of groundwater (USQRG:38,1,2)
  214. 670. three causes for contamination of drinking water
    natural dissolved substances, human waste products, and industrial waste products (USQRG:38,1,3)
  215. 671. seven most common compounds dissolved in groundwater
    chlorides; sulfates; calcium, magnesium, sodium, potassium, and iron bicarbonates (USQRG:38,1,4)
  216. 672. origin of dissolved compounds in groundwater
    weathered rocks (USQRG:38,2,0)
  217. 673. chief determinant of the composition of groundwater
    composition of the rock in which water occurs (USQRG:38,2,0)
  218. 674. two rocks containing much of the groundwater of the central United States
    limestone and dolostone (USQRG:38,2,0)
  219. 675. two compounds found in high amounts in groundwater of the central United States
    calcium and magnesium bicarbonates (USQRG:38,2,0)
  220. 676. hard water
    water rich in calcium and magnesium bicarbonates (USQRG:38,2,0)
  221. 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)
  222. 678. depositions made by hard water in pipes
    scaly crusts (USQRG:38,2,0)
  223. 679. soft water
    water with little dissolved matter and no appreciable calcium (USQRG:38,2,0)
  224. 680. two rocks commonly associated with soft water
    greywacke sandstone and volcanic rocks (USQRG:38,2,0)
  225. 681. region of the United States with generally soft water
    northwestern (USQRG:38,2,0)
  226. 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)
  227. 683. chemical formula of hydrogen sulfide
    H2S (USQRG:39,1,0)
  228. 684. odor of hydrogen sulfide
    rotten eggs (USQRG:39,1,0)
  229. 685. type of rock from which hydrogen sulfide in groundwater is derived
    sulfur‐rich (USQRG:39,1,0)
  230. 686. two compounds that are highly concentrated in arid regions, occasionally making groundwater non‐potable
    sulfates and chlorides (USQRG:39,1,0)
  231. 687. type of compound groundwater releases from porous sedimentary rocks in very dry regions
    salts (USQRG:39,1,0)
  232. 688. zone in which groundwater deposits salts in very dry regions
    zone of aeration (USQRG:39,1,0)
  233. 689. effect of salt on soil with regard to agriculture
    makes soil unsuitable for agriculture (USQRG:39,1,0)
  234. 690. most common source of water pollution in wells and springs
    sewage (USQRG:39,1,1)
  235. 691. size of pores in coarse gravel or cavernous limestone
    large (USQRG:39,1,1)
  236. 692. four potential sources of groundwater contamination from sewage
    septic tanks, broken sewers, privies, and barnyards (USQRG:39,1,1)
  237. 693. minimum distance needed for sewage‐contaminated groundwater to be purified
    30 meters (USQRG:39,2,0)
  238. 694. mineral that purifies sewage‐contaminated groundwater relatively quickly
    sand (USQRG:39,2,0)
  239. 695. distance for which sewage‐contaminated groundwater remains polluted in coarse gravel, relative to sand
    long distance (USQRG:39,1,1)
  240. 696. substance used by purification plants to treat municipal water supplies and sewage
    sand (USQRG:39,2,0)
  241. 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)
  242. 698. effect of oxidation on bacteria
    They are rendered harmless. (USQRG:39,2,0)
  243. 699. substance forming a barrier between fresh groundwater and seawater along coasts
    brackish water (USQRG:39,2,1)
  244. 700. thickness of the barrier between fresh groundwater and seawater along coasts
    thin (USQRG:39,2,1)
  245. 701. effect of pumping an aquifer near the coast on the flow of fresh groundwater to the sea
    reduction (USQRG:39,2,1)
  246. 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)
  247. 703. eventual result of excessive pumping from aquifers near the coast
    seawater intrusion (USQRG:40,1,0)
  248. 704. seawater intrusion
    salt water encroaching inland and contaminating freshwater supplies (USQRG:40,1,0)
  249. 705. difficulty of reversing seawater intrusion
    very difficult (USQRG:40,1,0)
  250. 706. two types of landfills
    open basins and excavations (USQRG:40,1,1)
  251. 707. step taken after a landfill reaches capacity
    covered with dirt (USQRG:40,1,1)
  252. 708. process allowed to take place after a landfill reaches capacity
    revegetation (USQRG:40,1,1)
  253. 709. How are waste products in covered landfills mobilized?
    water seepage carries away soluble substances in the waste products (USQRG:40,1,1)
  254. 710. factor determining the direction of flow of contaminated water from landfills
    regional groundwater flow pattern (USQRG:40,1,1)
  255. 711. rate at which contaminated water from landfills disperses
    same rate as percolating water in groundwater systems (USQRG:40,1,1)
  256. 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)
  257. 713. number of United States landfill sites identified to be creating pollution
    tens of thousands (USQRG:40,2,0)
  258. 714. two aspects of plants pesticides and herbicides are used to improve
    quality and productivity (USQRG:40,2,1)
  259. 715. two chief problems pesticides and herbicides can cause in humans
    cancer and birth defects (USQRG:40,2,1)
  260. 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)
  261. 717. pesticide mainly responsible for the reduction of the United States population of bald eagles
    DDT (USQRG:40,2,1)
  262. 718. reason pesticides reach groundwater
    precipitation flushes them into the soil (USQRG:40,2,1)
  263. 719. zone that disappears during excessive pumping of a coastal well
    brackish transition zone (USQRG:40,fig)
  264. 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)
  265. 721. leading environmental concern of industrialized countries
    necessity of dealing with highly toxic industrial wastes (USQRG:40,2,2)
  266. 722. two short‐term results of surface dumping of highly toxic industrial waste
    contamination of surface and subsurface water supplies (USQRG:40,2,2)
  267. 723. long‐term result of surface dumping of highly toxic industrial waste
    serious and potentially fatal health problems (USQRG:40,2,2)
  268. 724. environmental problem unique to nuclear‐capable countries
    disposal of radioactive waste products (USQRG:40,2,2)
  269. 725. two especially radioactive isotopes
    90Sr and 137Cs (USQRG:40,2,2)
  270. 726. amount of 90Sr required in the surface environment to be fatal to humans
    “minute quantities” (USQRG:41,1,0)
  271. 727. two categories of hazardous wastes
    toxic and radioactive (USQRG:41,1,1)
  272. 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)
  273. 729. maximum time span high‐level nuclear wastes can remain dangerous
    hundreds of thousands of years (USQRG:41,1,1)
  274. 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)
  275. 731. primary requirement for sites for high‐level nuclear waste disposal
    stability over a very long time span (USQRG:41,1,1)
  276. 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)
  277. 733. most immediate area of concern in placing hazardous wastes underground
    groundwater (USQRG:41,2,0)
  278. 734. What type of solvent is water?
    nearly universal (USQRG:41,2,0)
  279. 735. How acidic or basic is most groundwater?
    weakly acidic (USQRG:41,2,0)
  280. 736. Why is any underground container of hazardous waste likely to corrode?
    the acidity of passing groundwater (USQRG:41,2,0)
  281. 737. rate of circulation of water present in crustal rocks
    1 to 50 meters per year (USQRG:41,2,0)
  282. 738. ideal level of fracturing in the rock enclosing an underground radioactive waste storage site
    very low (USQRG:41,2,2)
  283. 739. ideal permeability of the rock enclosing an underground radioactive waste storage site
    low (USQRG:41,2,3)
  284. 740. ideal economic mineral potential of the rock enclosing an underground radioactive waste storage site
    none (USQRG:41,2,3)
  285. 741. relative rainfall in the area of an ideal underground radioactive waste storage site
    low (USQRG:42,1,3)
  286. 742. relative thickness of the zone of aeration in an ideal underground radioactive waste storage site
    thick (USQRG:42,1,4)
  287. 743. relative erosion rate in an ideal underground radioactive waste storage
    very low (USQRG:42,1,5)
  288. 744. ideal probability of earthquakes or volcanic activity in an underground radioactive waste storage site
    very low (USQRG:42,1,6)
  289. 745. knowledge needed by geologists to predict future geological events
    local and regional groundwater conditions (USQRG:42,1,8)
  290. 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)
  291. 747. feature in surface landfill which makes it safer than an open waste pond
    fully lined, preventing downward seepage of wastes (USQRG:41,fig)
  292. 748. type of rock unit required in the injection method of waste management
    deep and confined (USQRG:41,fig)
  293. 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)
  294. 750. Why is constant monitoring needed at injection wells used for waste management?
    The injection method is not foolproof. (USQRG:41,fig)
  295. 751. When does rainwater begin to chemically weather regolith and bedrock?
    as soon as it infiltrates the ground (USQRG:42,2,1)
  296. 752. dissolution
    process of chemical weathering in which minerals and rock materials pass directly into solution (USQRG:42,2,1; USQRG:101,2,9)
  297. 753. type of rock in Earth’s crust that most easily undergoes dissolution
    carbonates (USQRG:42,2,1)
  298. 754. three most common carbonate rocks
    limestone, dolostone, and marble (USQRG:42,2,2)
  299. 755. solubility of carbonate minerals in pure water
    nearly insoluble (USQRG:42,2,2)
  300. 756. relative proportion of the Earth’s surface underlain by limestone, dolostone, and marble
    large majority (USQRG:42,2,2)
  301. 757. acid present in rainwater that dissolves carbonate minerals
    carbonic (USQRG:42,2,2)
  302. 758. cations present in groundwater from the dissolution of carbonate minerals
    calcium (USQRG:42,2,2)
  303. 759. anions present in groundwater from the dissolution of carbonate minerals
    bicarbonate (USQRG:42,2,2)
  304. 760. portions of carbonate rocks that are most affected by groundwater weathering
    joints and other partings (USQRG:42,2,3)
  305. 761. granite mineral largely resistant to weathering
    quartz (USQRG:42,2,3)
  306. 762. result of limestone weathering
    Nearly all the minerals dissolve away into slowly moving groundwater. (USQRG:42,2,3)
  307. 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)
  308. 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)
  309. 765. geological feature that may cause the dissolution rate to exceed the average rate of surface erosion
    streams (USQRG:43,1,0)
  310. 766. substance responsible for most conversion of sediment in sedimentary rock
    groundwater (USQRG:43,1,1)
  311. 767. most common type of iron compound in sedimentary rocks
    hydroxides (USQRG:43,1,1)
  312. 768. saturated zone
    region of the ground in which sediment is saturated with water (USQRG:43,1,1)
  313. 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)
  314. 770. three chief cementing substances in sedimentary rocks
    quartz, calcite, and iron compounds (USQRG:43,1,1)
  315. 771. most common cementing substance in sedimentary rocks
    calcite (USQRG:43,1,1)
  316. 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)
  317. 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)
  318. 774. two types of substances that can undergo replacement
    mineral and organic (USQRG:43,1,2)
  319. 775. common example of the replacement of organic matter
    petrified wood (USQRG:43,1,2)
  320. 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)
  321. 777. identifying characteristic of rocks in regions with many caves and sinkholes
    exceptionally soluble (USQRG:43,1,3)
  322. 778. drainage pattern in regions with many caves and sinkholes
    disrupted (USQRG:43,2,0)
  323. 779. geological features streams reappear as in landscapes with numerous caves and sinkholes
    large springs (USQRG:43,2,0)
  324. 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)
  325. 781. former country in which the Karst region lies
    Yugoslavia (USQRG:43,2,0)
  326. 782. characteristic feature of the Karst region’s landscape
    closely spaced sinkholes (USQRG:43,2,0)
  327. 783. most common type of rock in karst landscapes
    carbonate (USQRG:43,2,0)
  328. 784. four types of rock in which karst landscapes may develop
    carbonate, dolomite, gypsum, and salt (halite) (USQRG:43,2,0)
  329. 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)
  330. 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)
  331. 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)
  332. 788. most common type of karst landscape
    sinkhole karst (USQRG:43,2,2)
  333. 789. sinkhole karst
    landscape dotted with sinkholes of various sizes and shapes (USQRG:43,2,2)
  334. 790. three American states in which sinkhole karst landscapes are most common
    Indiana, Kentucky, and Tennessee (USQRG:43,2,2)
  335. 791. island nation on which sinkhole karst landscapes are commonly found
    Jamaica (USQRG:43,2,2)
  336. 792. cone karst
    closely spaced conical‐ or pinnacle‐ shaped hills separated by deep sinkholes (USQRG:43,2,3)
  337. 793. tower karst
    isolated tower‐like hills separated by expanses of alluvium (USQRG:43,2,3)
  338. 794. rock underlying cone and tower karst landscapes
    thick, well‐jointed limestone (USQRG:43,2,3)
  339. 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)
  340. 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)
  341. 797. two Caribbean islands on which cone and tower karst landscapes are found
    Cuba and Puerto Rico (USQRG:43,2,3)
  342. 798. Guilin’s country
    China (USQRG:43,2,4)
  343. 799. type of karst landscape found near Guilin, China
    tower karst (USQRG:43,2,4)
  344. 800. height of vertical‐sided peaks of limestone in the karst landscape near Guilin, China
    200 meters (USQRG:45,1,6)
  345. 801. pavement karst
    areas of bare limestone in which dissolution has etched and widened joints and bedding planes (USQRG:45,1,7)
  346. 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)
  347. 803. Greenland city known for its pavement karst landscapes
    Spitzbergen (USQRG:45,1,7)
  348. 804. region of Ireland known for its pavement karst landscapes
    Burren (USQRG:45,1,7)
  349. 805. element with atomic number 34
    selenium (USQRG:43,1,4)
  350. 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)
  351. 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)
  352. 808. Kesterson National Wildlife Refuge’s state
    California (USQRG:43,1,5)
  353. 809. valley in which Kesterson National Wildlife Refuge is located
    San Joaquin Valley (USQRG:43,1,5)
  354. 810. climate of western San Joaquin Valley
    arid (USQRG:45,1,1)
  355. 811. effect of irrigation on the water table in San Joaquin Valley
    rose significantly (USQRG:45,1,1)
  356. 812. method by which excess water due to irrigation in the San Joaquin Valley was removed
    system of subsurface drains (USQRG:45,1,1)
  357. 813. natural source of selenium near San Joaquin Valley
    Coast Ranges (USQRG:45,1,2)
  358. 814. annual rainfall of the Coast Ranges
    less than 250 millimeters (USQRG:45,1,2)
  359. 815. annual evaporation rate of the Coast Ranges
    approximately 2,300 millimeters (USQRG:45,1,2)
  360. 816. Why has selenium concentrated in the Kesterson Reservoir?
    The reservoir has no outlet. (USQRG:45,1,2)
  361. 817. two chemical properties of the shallow groundwater of the San Joaquin Valley
    alkaline and slightly to highly saline (USQRG:45,1,3)
  362. 818. relative solubility of selenium in the shallow groundwater of the San Joaquin Valley
    high (USQRG:45,1,3)
  363. 819. depth of a clay layer beneath the San Joaquin Valley
    3 to 23 meters (USQRG:45,1,4)
  364. 820. geographic feature resulting from the clay layer beneath the San Joaquin Valley
    perched water body (USQRG:45,1,4)
  365. 821. paleogeography
    geography of the past (USQRG:45,2,1)
  366. 822. record used to reconstruct ancient environments
    stratigraphic (USQRG:45,2,1)
  367. 823. organisms whose skeletons form calcareous ooze on the deep sea floor
    single‐celled plankton (USQRG:46,fig)
  368. 824. type of location at which coarse‐grained alluvial fans form
    emergence of streams from mountains (USQRG:46,fig)
  369. 825. stone released by icebergs
    dropstone (USQRG:46,fig)
  370. 826. climate of lakes in which seasonal varves form
    cold (USQRG:46,fig)
  371. 827. geological feature that clogs braided streams
    bar (USQRG:46,fig)
  372. 828. type of sand that accumulates in braided streams
    cross‐bedded gravelly sand (USQRG:46,fig)
  373. 829. type of water from which evaporites precipitate in dry climates
    hypersaline (USQRG:46,fig)
  374. 830. geological feature resulting from winds in barrier islands
    cross bedded sand dunes (USQRG:46,fig)
  375. 831. geological feature on which oolites form in shallow tropical seas
    shoals (USQRG:46,fig)
  376. 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)
  377. 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)
  378. 834. animal category that creates mottled textures in sandy lagoon muds
    burrowers (USQRG:47,fig)
  379. 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)
  380. 836. lagoon
    shallow pond or lake on the edge of the ocean but separated from it (USQRG:48,1,0; USQRG:102,1,13)
  381. 837. mammal once considered extremely similar to the largest dinosaurs
    hippopotamus (USQRG:48,1,1)
  382. 838. object in soil around which white nodules of calcium carbonate form
    plant roots (USQRG:48,1,fig)
  383. 839. type of sediment in which petroleum and natural gas tend to accumulate
    porous (USQRG:48,2,0)
  384. 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)
  385. 841. organisms that often construct limestone reefs in shallow seas
    coral (USQRG:48,2,0)
  386. 842. actualism
    studying modern deposition patterns to reconstruct ancient deposits in similar environments (USQRG:48,2,1)
  387. 843. coring
    driving a tube into a sedimentary deposit to withdraw the contents (USQRG:48,2,1)
  388. 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)
  389. 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)
  390. 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)
  391. 847. animal whose burrows fossilized into “devil’s corkscrews”
    beavers (USQRG:48,2,fig)
  392. 848. state whose grasslands were inhabited by beavers 20 million years ago
    Nebraska (USQRG:48,2,fig)
  393. 849. type of environment that produced most coal deposits
    swamps choked with vegetation (USQRG:48,2,2)
  394. 850. two types of locations in which swamps choked with vegetation are found
    banks of rivers and marine lagoons (USQRG:49,1,0)
  395. 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)
  396. 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)
  397. 853. Lake Louise’s Canadian province
    Alberta (USQRG:49,fig)
  398. 854. soil
    loose sediment that contains organic matter accumulated in contact with the atmosphere, not underwater (USQRG:49,1,1)
  399. 855. two types of substances on which soil can rest
    sediment or rock (USQRG:49,1,1)
  400. 856. two ways in which soil benefits plants
    supplies essential nutrients and physically supports plants (USQRG:49,1,1)
  401. 857. two processes by which most soil forms
    weathering and decay of plant material (USQRG:49,1,1)
  402. 858. topsoil
    upper zone of many soils (USQRG:49,1,1)
  403. 859. three main components of topsoil
    sand, clay, and humus (USQRG:49,1,1)
  404. 860. humus
    organic matter that gives topsoil its dark color (USQRG:49,1,1)
  405. 861. process that creates humus
    bacteria‐caused decay of plant debris (USQRG:49,2,0)
  406. 862. caliche
    calcium carbonate precipitated as massive deposits due to groundwater evaporation (USQRG:49,2,1)
  407. 863. type of climate in which caliche forms
    warm climates that are dry for part of the year (USQRG:49,2,1)
  408. 864. process that destroys humus
    oxidization (USQRG:49,2,1)
  409. 865. type of climate in which humus is destroyed by warm water percolation
    moist and tropical (USQRG:49,2,1)
  410. 866. laterites
    soils rich in iron and aluminum oxides (USQRG:49,2,1)
  411. 867. color of laterites
    rusty red (USQRG:49,2,1)
  412. 868. type of mineral that breaks down quickly under warm water percolation, creating laterites
    silicate (USQRG:49,2,1)
  413. 869. process by which most soil is destroyed
    erosion (USQRG:49,2,2)
  414. 870. reason ancient buried soils can be difficult to recognize and interpret
    Chemical components are often altered beyond recognition. (USQRG:50,1,0)
  415. 871. type of location likely to contain an ancient soil
    beneath an unconformity (USQRG:50,1,0)
  416. 872. two epochs in which “devil’s corkscrews” formed
    Oligocene and Miocene (USQRG:50,1,0)
  417. 873. greatest distance underground that ancient beavers lived
    10 meters (USQRG:50,1,0)
  418. 874. environmental role of freshwater lakes and glaciers
    supply reservoirs on land (USQRG:50,1,1)
  419. 875. geological epoch in which lakes occupied a large fraction of Earth’s surface
    none (USQRG:50,1,2)
  420. 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)
  421. 877. event indicated by historical presence of large freshwater lakes
    abundant precipitation (USQRG:50,1,3)
  422. 878. method by which large freshwater lakes receive a substantial portion of their water
    runoff from land (USQRG:50,1,3)
  423. 879. characteristic of large freshwater lakes that stabilizes the temperature of nearby land areas
    high heat capacity of water (USQRG:50,1,3)
  424. 880. texture of sediments around the margins of a freshwater lake compared to those at the center
    coarser (USQRG:50,1,4)
  425. 881. varves
    alternating coarse‐ and fine‐grained layers resulting from seasonal depositions (USQRG:50,1,4)
  426. 882. type of season in which a freshwater lake receives almost all of its coarse sediment
    moist (USQRG:50,1,4)
  427. 883. area of deep lakes at which wind‐driven waves touch the lake bottom
    only approaching the shore (USQRG:50,1,4)
  428. 884. two types of exclusively marine fossils
    corals and echinoderms (USQRG:50,1,5)
  429. 885. relative strength of waves and currents in lakes
    generally weak (USQRG:50,2,0)
  430. 886. abundance of burrowing animals in marine environments compared to lakes
    more frequent (USQRG:50,2,0)
  431. 887. continental shelf
    gently sloping zone of shallowly submerged land surrounding the continents (USQRG:50,2,1; USQRG:101,1,17)
  432. 888. barrier commonly present in between deep‐sea deposits and lake deposits
    unconformity (USQRG:50,2,1)
  433. 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)
  434. 890. time span for which records of continental glaciers survive
    hundreds of millions of years (USQRG:50,2,2)
  435. 891. two modern continental glaciers
    one occupying most of Greenland and one covering nearly all of Antarctica (USQRG:50,2,2)
  436. 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)
  437. 893. till
    unconsolidated, unsorted sediments deposited by glaciers (USQRG:50,2,4; USQRG:103,2,5)
  438. 894. tillite
    lithified till (USQRG:50,2,4)
  439. 895. moraine
    accumulation of sediment deposited at the farthest reach of a glacier (USQRG:50,2,4)
  440. 896. meltwater
    streams issuing from the front of a retreating glacier (USQRG:50,2,4)
  441. 897. outwash
    well‐stratified sediment found in meltwater consisting of gravel, cross‐bedded sand, and mud (USQRG:50,2,4)
  442. 898. geological feature often formed in front of a retreating glacier
    lake (USQRG:50,2,5)
  443. 899. season in which coarse sediment layers form in glacial lakes
    summer (USQRG:50,2,5)
  444. 900. material carried into glacial lakes by meltwater in the summer
    sand (USQRG:51,1,0)
  445. 901. season in which fine layers of sediment form in glacial lakes
    winter (USQRG:51,1,0)
  446. 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)
  447. 903. How does abundant organic matter in glacial lakes’ sediment layers affect the lakes’ color?
    darkens (USQRG:51,1,0)
  448. 904. time span represented by a pair of sediment layers in a glacial lake
    1 year (USQRG:51,1,0)
  449. 905. pieces of glacier that break off into lakes or oceans
    icebergs (USQRG:51,1,1)
  450. 906. two characteristics of glacial till
    tightly packed and coarse (USQRG:51,1,1)
  451. 907. dropstone
    glacial sediment dropped into a lake or ocean (USQRG:51,1,1)
  452. 908. ice rafting
    icebergs breaking off from glaciers, resulting in the deposition of large stones in lakes or oceans (USQRG:51,1,1)
  453. 909. frequency of organic matter in desert soils
    low (USQRG:51,1,2)
  454. 910. source of organic matter in soils
    vegetation (USQRG:51,1,2)
  455. 911. two processes caused by desert rain
    erosion and deposition of sediment (USQRG:51,1,2)
  456. 912. geological feature that carries chemical products of weathering to desert basins
    temporary streams (USQRG:51,1,2)
  457. 913. exterior drainage
    runoff water and sediment from beyond a region’s borders (USQRG:51,1,2)
  458. 914. type of region that experiences exterior drainage
    humid (USQRG:51,1,2)
  459. 915. interior drainage
    pattern in which streams dry up through evaporation, seepage into dry terrain, or drainage into lakes (USQRG:51,1,2)
  460. 916. type of region that experiences interior drainage
    arid (USQRG:51,1,2)
  461. 917. playa lakes
    lakes in areas with interior drainage (USQRG:51,1,2)
  462. 918. How permanent are playa lakes?
    temporary (USQRG:51,1,2)
  463. 919. dune
    hill of loose sand formed by the wind (USQRG:51,1,3; USQRG:101,2,11)
  464. 920. type of region in which dunes form
    dry and sparsely vegetated (USQRG:51,1,3)
  465. 921. percentage of deserts occupied by dunes
    less than 1 (USQRG:51,1,3)
  466. 922. direction in which a dune crawls
    downwind (USQRG:51,1,3)
  467. 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)
  468. 924. trough cross‐stratification
    new sets of sediment beds accumulating on a curved surface, cutting through older sets (USQRG:51,2,0)
  469. 925. part of a dune at which a windstream becomes compressed
    just above (USQRG:51,fig)
  470. 926. point at which a dune stops growing
    The height causes the windstream to move rapidly enough to transport sand. (USQRG:51,fig)
  471. 927. Which side of a dune has a steep slope?
    downwind or leeward (USQRG:51,fig)
  472. 928. climate typified by Death Valley
    arid basin (USQRG:52,1,1)
  473. 929. Death Valley’s state
    California (USQRG:52,1,1)
  474. 930. geological belt in which dry climates are commonly found
    trade wind (USQRG:52,1,0)
  475. 931. mountain feature that creates dry climates
    rain shadow (USQRG:52,1,0)
  476. 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)
  477. 933. type of particles that form alluvial fans
    poorly sorted and sedimentary (USQRG:52,1,1)
  478. 934. type of material in alluvial fans near the source area
    range from boulders to sand (USQRG:52,2,0)
  479. 935. type of material in alluvial fans on low, gentle slopes
    range from sand to mud (USQRG:52,2,0)
  480. 936. braided stream
    stream in which sand bars cause a series of separating and uniting channels (USQRG:52,2,0)
  481. 937. direction of flow of a braided stream in an arid basin
    toward the center (USQRG:52,2,1)
  482. 938. minerals accumulated as a playa lake dries up
    evaporite (USQRG:52,2,1)
  483. 939. three chief evaporites in Death Valley
    halite, gypsum, and anhydrite (USQRG:52,2,1)
  484. 940. salt pans
    large polygonal mudcracks formed in arid basins by alternate wetting and drying (USQRG:53,1,0)
  485. 941. geological feature formed by calcium carbonate deposition near salt pans
    caliche (USQRG:53,1,0)
  486. 942. type of drainage normally present in areas with abundant rainfall
    exterior (USQRG:53,1,1)
  487. 943. location of alluvial fans in moist regions
    at the foot of mountains and steep hills (USQRG:53,1,2)
  488. 944. slope of alluvial fans in moist regions compared to those in arid regions
    gentler (USQRG:53,1,2)
  489. 945. level of vegetation on alluvial fans
    poor (USQRG:53,1,2)
  490. 946. reason for the level of vegetation present on alluvial fans
    steep slopes (USQRG:53,1,2)
  491. 947. two events that trigger the formation of braided streams in alluvial fans in moist regions
    heavy rainfall or snowmelt (USQRG:53,1,2)
  492. 948. type of glaciers that form braided streams
    those that experience substantial melting in summer (USQRG:53,1,2)
  493. 949. meandering rivers
    streams that occupy solitary channels, winding back and forth like ribbons (USQRG:53,1,3)
  494. 950. two large meandering rivers
    Mississippi and Thames (USQRG:53,1,3)
  495. 951. amount of sediment in meandering rivers compared to that in braided streams
    significantly lower (USQRG:53,1,3)
  496. 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)
  497. 953. cause of curvature in a meandering river
    any irregularity in the local terrain (USQRG:53,1,3)
  498. 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)
  499. 955. Which bank does a meandering river cut into when rounding a bend?
    outer (USQRG:53,1,3)
  500. 956. point bar
    deposition of sediment in the inside of a bend in a meandering river (USQRG:53,1,3)
  501. 957. most common substance in point bars
    sand (USQRG:53,1,4)
  502. 958. arrangement of minerals in point bars
    cross‐bedded (USQRG:53,1,4)
  503. 959. two minerals commonly found on the riverbed of deep meandering rivers
    gravel and sand (USQRG:53,1,3)
  504. 960. Why does mud not settle in a meandering river?
    consists of very fine particles (USQRG:53,2,1)
  505. 961. floodplains
    lowlands adjacent to a meandering river (USQRG:53,2,1)
  506. 962. backswamps
    lowlands adjacent to a meandering river (USQRG:53,2,1)
  507. 963. rate of flow of floodwaters in floodplains
    slow (USQRG:53,2,1)
  508. 964. change in flow rate of floodwaters further away from floodplain channels
    decreasing (USQRG:53,2,1)
  509. 965. first two materials deposited by floodwaters in floodplains
    sand and silt (USQRG:53,2,1)
  510. 966. natural levee
    gentle ridge of sand and silt beside a river channel and floodplains (USQRG:53,2,1)
  511. 967. geological feature that eventually forms over point‐bar depositions
    floodplains (USQRG:53,fig)
  512. 968. frequency of flooding for natural levees and floodplains
    only periodically (USQRG:53,fig)
  513. 969. geological feature formed when floodplains and natural levees dry out
    mudcracks (USQRG:54,1,0)
  514. 970. What record shows the earlier existence of moisture‐loving plants on floodplains?
    traces of roots in the rock record (USQRG:54,1,0)
  515. 971. mineral formed by deposits of plants
    coal (USQRG:54,1,0)
  516. 972. type of sequence in which sediments are deposited by a meandering river
    vertical (USQRG:54,1,0)
  517. 973. sediment at the bottom of deposits made by a meandering river
    coarse channel deposits (USQRG:54,1,1)
  518. 974. sediment at the middle of deposits made by a meandering river
    cross‐bedded point‐bar sands (USQRG:54,1,1)
  519. 975. sediment at the top of deposits made by a meandering river
    muddy backswamp deposits (USQRG:54,1,1)
  520. 976. location of levee sediments in the deposits of a meandering river
    between cross‐bedded and backswamp deposits (USQRG:54,1,1)
  521. 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)
  522. 978. subsiding basin
    basin sinking relative to the surrounding terrain (USQRG:54,1,2)
  523. 979. sedimentary cycle
    coarse‐to‐fine composite depositional unit from a meandering river (USQRG:54,1,2)
  524. 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)
  525. 981. location that a river in a moist region deposits its entire load of sediment
    a lake or the sea (USQRG:54,1,3)
  526. 982. pattern of sediment deposition at the end of a river
    fanlike (USQRG:54,1,4)
  527. 983. result of a current reaching the end of a river
    dissipation (USQRG:54,1,4)
  528. 984. delta
    depositional body of sand, silt, and clay formed when a river deposits it sediment (USQRG:54,1,4; USQRG:101,2,7)
  529. 985. How did a delta get its name?
    resemblance to the Greek letter delta (Δ) (USQRG:54,1,4)
  530. 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)
  531. 987. three deposits of a delta structure
    delta‐plain, delta‐front, and prodelta (USQRG:54,2,0)
  532. 988. delta‐plain beds
    delta deposits consisting mostly of sand and silt (USQRG:54,2,1)
  533. 989. orientation of delta‐plain beds
    horizontal, except for a few cross‐bedded areas (USQRG:54,2,1)
  534. 990. distributary channels
    smaller channels branched from the main river channel that radiate outwards in a delta (USQRG:54,2,1)
  535. 991. material that forms the floor of distributary channels
    cross‐bedded sand (USQRG:54,2,1)
  536. 992. two geological features found between distributary channels
    natural levees and swamps (USQRG:54,2,1)
  537. 993. delta‐front beds
    delta deposits sloping seaward from the delta plain (USQRG:54,2,2)
  538. 994. two main materials in delta‐front beds
    silt and clay (USQRG:54,2,2)
  539. 995. environmental system in which delta‐front beds fully lie
    marine (USQRG:54,2,2)
  540. 996. type of organisms found in delta‐front muds
    marine fauna (USQRG:54,2,2)
  541. 997. fragments often found in delta‐front muds
    waterlogged wood (USQRG:54,2,2)
  542. 998. prodelta beds
    farthest delta bed, spreading seaward at a low angle (USQRG:55,1,1)
  543. 999. material that forms most prodelta beds
    clay (USQRG:55,1,1)
  544. 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)
  545. 1001. density of freshwater compared to sea water
    less dense (USQRG:55,2,0)
  546. 1002. progradation
    seaward growth of a delta (USQRG:55,2,1; USQRG:57,1,1)
  547. 1003. progression of delta deposits in a core sample, according to Walther’s law
    delta‐plain, delta‐front, and prodelta (USQRG:55,2,1)
  548. 1004. the Mississippi River’s final destination
    Gulf of Mexico (USQRG:55,2,2)
  549. 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)
  550. 1006. river‐dominated delta
    delta constructed from river‐borne sediment, not forces of the sea (USQRG:55,2,2)
  551. 1007. active lobe of a delta
    portion of the delta that is growing (USQRG:55,2,2)
  552. 1008. location of distributary channels in a river‐dominated delta
    the active lobe (USQRG:55,2,2)
  553. 1009. dating method used for previously active lobes of the Mississippi River delta
    carbon‐14 dating (USQRG:55,2,2)
  554. 1010. another name for delta lobe growth
    depositional activity (USQRG:55,2,2)
  555. 1011. How do sediments in an abandoned delta lobe change over time?
    compact under their own weight (USQRG:55,2,3)
  556. 1012. Why are delta structures always sinking?
    isostatic response of the crust to the constantly increasing mass of sediment (USQRG:55,2,3)
  557. 1013. location at which young delta lobes form
    atop abandoned delta lobes (USQRG:55,2,3)
  558. 1014. superimposition
    layering of one delta lobe over another previously formed (USQRG:55,2,4)
  559. 1015. difficulty of erosion of previously constructed delta lobes
    easy (USQRG:55,2,4)
  560. 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)
  561. 1017. two factors affecting the size of a delta lobe
    rate of sinkage and supply of sediment (USQRG:55,2,5)
  562. 1018. current rate of growth of the Mississippi River delta
    rapid shrinkage (USQRG:56,1,0)
  563. 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)
  564. 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)
  565. 1021. number of square miles of the Louisiana coast lost every year
    approximately 40 (USQRG:56,2,0)
  566. 1022. location of the United States’ largest waterfowl population
    the Mississippi River delta (USQRG:56,2,0)
  567. 1023. effect of the Gulf of Mexico on the Mississippi River delta
    increasing encroachment on the delta (USQRG:56,2,0)
  568. 1024. percentage of the annual United States seafood harvest supplied by the Mississippi River delta
    nearly 30% (USQRG:56,2,0)
  569. 1025. barrier islands
    land masses that border long stretches of shoreline without large river deltas (USQRG:56,2,1)
  570. 1026. main component of barrier islands
    clean sand (USQRG:56,2,1)
  571. 1027. Where is the sand that forms barrier islands derived from?
    the sea (USQRG:56,2,1)
  572. 1028. longshore currents
    shallow currents that flow along the coast (USQRG:56,2,1)
  573. 1029. How are barrier islands formed?
    Waves and longshore currents sweep sand parallel to the shoreline. (USQRG:56,2,1)
  574. 1030. type of beaches that have barrier islands with nearly horizontal bedding
    those washed by breaking waves (USQRG:56,2,1)
  575. 1031. type of beaches that have cross‐bedded barrier islands
    those with irregular surfaces and that experience periodic change (USQRG:56,2,1)
  576. 1032. type of sediment trapped by lagoons
    fine‐grained (USQRG:56,2,2)
  577. 1033. two materials typically found in lagoon floors
    mud and muddy sands (USQRG:56,2,2)
  578. 1034. geological feature often constructed by small rivers along the landward margins of lagoons
    deltas (USQRG:56,2,2)
  579. 1035. barrier island‐lagoon complex
    barrier island and the lagoon behind it (USQRG:56,2,2)
  580. 1036. geographical feature separating adjacent barrier islands in a chain
    tidal channels (USQRG:56,2,3)
  581. 1037. type of bedding in tidal deltas
    cross‐bedded (USQRG:56,2,3)
  582. 1038. tidal flats
    depositional environment found along lagoon shores (USQRG:56,2,3)
  583. 1039. two main materials that form tidal flats
    sand or muddy sand (USQRG:56,2,3)
  584. 1040. geological feature that periodically exposes and floods tidal flats
    the ocean’s tide (USQRG:56,2,3)
  585. 1041. altitude of tidal flats compared to lagoon marshes
    much lower (USQRG:56,2,3)
  586. 1042. material formed by rapid plant material decomposition
    peat (USQRG:56,2,3)
  587. 1043. Which deltaic cycle receives the lowest number in a numbering of several superimposed cycles?
    the lowest/oldest (USQRG:56,fig)
  588. 1044. Why is most of the water in lagoons in moist climates brackish?
    Water remains trapped for some time. (USQRG:56,2,4)
  589. 1045. factor affecting the salinity of lagoon water
    rate of freshwater runoff from land (USQRG:56,2,4)
  590. 1046. climate of the lagoon Laguna Madre
    warm and arid (USQRG:56,2,4)
  591. 1047. state in which the lagoon Laguna Madre is located
    Texas (USQRG:56,2,4)
  592. 1048. salinity of the lagoon Laguna Madre
    hyper‐saline (USQRG:56,2,4)
  593. 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)
  594. 1050. Why are many forms of marine life excluded from lagoons?
    abnormal and fluctuating salinity (USQRG:57,1,0)
  595. 1051. relative diversity of fossil fauna in ancient sediments of lagoons
    sparse (USQRG:57,1,0)
  596. 1052. common burrower in ancient lagoons
    segmented worms (USQRG:57,1,0)
  597. 1053. effect of burrowers on lagoons
    mottled sediments devoid of bedding structure (USQRG:57,1,0)
  598. 1054. effect of high sedimentation rates on a barrier island‐lagoon complex
    progradation (USQRG:57,1,1)
  599. 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)
  600. 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)
  601. 1057. process by which the horizontal sequence of a barrier island‐lagoon complex becomes a vertical sequence
    progradation (USQRG:57,1,1)
  602. 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)
  603. 1059. effect of strong tidal waves on open continental shelves with abundant sand
    Sand spreads out into sheets. (USQRG:57,2,0)
  604. 1060. tempestites
    sandy beds produced by storms (USQRG:57,2,1)
  605. 1061. thickness of most tempestites
    a few centimeters (USQRG:57,2,1)
  606. 1062. two materials that typically accumulated on quiet continental shelves
    mud and muddy sand (USQRG:57,2,1)
  607. 1063. direction of Wales relative to central England
    west (USQRG:57,2,3)
  608. 1064. orientation of mid‐Silurian marine invertebrate fossils found in Wales relative to the shoreline then
    roughly parallel (USQRG:57,2,3)
  609. 1065. Lingula
    inarticulate brachiopod genus (USQRG:57,2,3)
  610. 1066. amount of species found in mid‐Silurian fossils in Wales
    few (USQRG:57,2,3)
  611. 1067. type of water found in ancient Wales near the site of mid‐Silurian fossils
    brackish (USQRG:57,2,3)
  612. 1068. two types of coastal environments tolerated by Lingula today
    brackish and of variable salinity (USQRG:57,2,3)
  613. 1069. stability of the center and seaward margin of a lagoon, compared to the shoreline
    more stable (USQRG:57,2,4)
  614. 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)
  615. 1071. area of lagoon deposits to which trilobites fossils are restricted
    finer‐grained sediments far offshore (USQRG:57,2,5)
  616. 1072. identifying characteristic of a stable offshore shelf environment
    high diversity of species (USQRG:57,2,5)
  617. 1073. stabilizing feature of offshore shelf environments
    removal from the influence of river water (USQRG:57,2,5)
  618. 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)
  619. 1075. planktonic graptolites
    fragile colonial animals (USQRG:58,1,0)
  620. 1076. prevailing type of sedimentation in tropical shallow marine settings lacking siliciclastic sediments
    carbonate (USQRG:58,2,1)
  621. 1077. geological feature often present in tropical shallow marine settings lacking siliciclastic sediments
    coral reefs (USQRG:58,2,1)
  622. 1078. type of rock in which reefs form their depositional records
    limestone (USQRG:58,2,1)
  623. 1079. How do reefs form their own depositional records?
    secretion of calcium carbonate by reefs’ own organisms (USQRG:58,2,1)
  624. 1080. type of water in which modern reefs grow
    shallow water with high clarity and normal marine salinity (USQRG:59,1,0)
  625. 1081. type of host water for ancient reefs, compared to that for modern reefs
    none (USQRG:59,1,0)
  626. 1082. substance used in the basic framework of a reef
    calcareous skeletons or organisms (USQRG:59,1,1)
  627. 1083. primary organism incorporated into a reef’s structure
    coral (USQRG:59,1,1)
  628. 1084. How is the framework of a reef strengthened?
    cementation of organisms that encrust the surface of the reef (USQRG:59,1,1)
  629. 1085. main component of carbonate sediment of reefs
    skeletons of reef‐dwelling organisms (USQRG:59,1,1)
  630. 1086. How does a reef fill its voids during construction?
    trapping carbonate sediment in the porous framework (USQRG:59,1,1)
  631. 1087. degree of bedding of reef limestone
    nonexistent or poorly bedded (USQRG:59,1,1)
  632. 1088. valuable commodity often trapped by ancient buried reefs
    petroleum (USQRG:59,1,1)
  633. 1089. Why do reefs alter nearby patterns of sedimentation?
    stand above the surrounding seafloor (USQRG:59,1,2)
  634. 1090. position of the leeward side of a reef, relative to the rest of the reef
    side nearest the land (USQRG:59,1,2)
  635. 1091. geological feature typically on the leeward side of a reef
    relatively calm lagoon (USQRG:59,1,2)
  636. 1092. reef flat
    horizontal upper surface of a reef that can reach close to sea level (USQRG:59,1,2)
  637. 1093. structure of a reef below its living surface
    limestone core consisting of dead skeletal framework and trapped sediment (USQRG:59,2,0)
  638. 1094. talus
    pile of rubble in a reef’s limestone core that has fallen from the reef front (USQRG:59,2,0)
  639. 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)
  640. 1096. two basic structural features of modern reefs
    seaward talus deposits and leeward back‐reef strata (USQRG:59,2,1)
  641. 1097. time at which the reef flat of a reef growing up to sea level is exposed
    low tide (USQRG:59,fig)
  642. 1098. two areas near barrier reefs at which sediment accumulates
    back‐reef area and in the lagoon (USQRG:59,fig)
  643. 1099. patch reefs
    isolated reefs formed in lagoons behind elongate reefs (USQRG:59,2,2)
  644. 1100. barrier reefs
    elongate reefs at the edge of lagoons facing the open sea (USQRG:59,2,2)
  645. 1101. fringing reefs
    reefs that grow along the coastline without a lagoon behind them (USQRG:59,2,2)
  646. 1102. eventual effect of fringing reefs growing seaward
    become barrier reefs (USQRG:59,2,2)
  647. 1103. atoll
    island reefs made of coral (USQRG:59,2,3; USQRG:101,1,8)
  648. 1104. two possible atoll shapes
    circular or horseshoe‐shaped (USQRG:59,2,3)
  649. 1105. geological location at which atolls form
    volcanic islands (USQRG:59,2,3)
  650. 1106. region known for its atolls
    tropical Pacific (USQRG:60,1,0)
  651. 1107. scientist who developed the modern explanation for Pacific atolls
    Charles Darwin (USQRG:60,1,0)
  652. 1108. first stage in the development of a Pacific atoll
    volcano rises from the ocean floor (USQRG:60,fig; USQRG:60,1,0)
  653. 1109. second stage in the development of a Pacific atoll
    fringing reef colonizes an extinct volcano (USQRG:60,fig; USQRG:60,1,0)
  654. 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)
  655. 1111. final stage in the development of a Pacific atoll
    island sinks completely, leaving a circular reef (USQRG:60,fig; USQRG:60,1,0)
  656. 1112. type of stone that accumulates in the central lagoon of an atoll
    limestone (USQRG:60,1,0)
  657. 1113. side of a horseshoe‐shaped atoll broken the most often
    leeward (USQRG:60,2,0)
  658. 1114. maximum diameter of horseshoe‐shaped atolls
    approximately 40 miles (USQRG:60,2,0)
  659. 1115. function of atolls’ lagoons during World War II
    natural harbors for ships (USQRG:60,2,0)
  660. 1116. How can ancient atolls lying beneath younger sediments be identified?
    studying cores of rock brought up from drilling operations (USQRG:60,2,1)
  661. 1117. carbonate platform
    broad calcium carbonate structure rising above the seafloor on at least one side (USQRG:60,2,2)
  662. 1118. Why do organic reefs often grow near carbonate platforms?
    Windward margins contain abundant food sources. (USQRG:60,2,2)
  663. 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)
  664. 1120. solubility of carbon dioxide in cold water compared to that in warm water
    more soluble (USQRG:60,2,3)
  665. 1121. chemical formula of carbonic acid
    H2CO3 (USQRG:60,2,3)
  666. 1122. two compounds that react to form carbonic acid
    carbon dioxide (CO2) and water (H2O) (USQRG:60,2,3)
  667. 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)
  668. 1124. chemical formula of calcium carbonate
    CaCO3 (USQRG:60,2,5)
  669. 1125. chemical formula of a calcium ion
    Ca2+ (USQRG:60,2,5)
  670. 1126. chemical formula of a bicarbonate ion
    HCO3‐ (USQRG:60,2,5)
  671. 1127. chemical equation of the process of calcium carbonate being broken down by carbonic acid
    H2CO3 + CaCO3 = Ca2+ + 2HCO3‐ (USQRG:60,2,5)
  672. 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)
  673. 1129. level of carbonic acid in warm tropical seas favoring organic reef growth
    low (USQRG:60,2,6)
  674. 1130. coast of the United States that once housed carbonate platforms
    eastern (USQRG:60,2,7)
  675. 1131. Why are carbonate platforms geographically restricted today?
    coolness of Earth’s climate compared to much of history (USQRG:60,2,7)
  676. 1132. peninsula in the western Atlantic and Caribbean region that houses a large carbonate platform
    Yucatan (USQRG:60,2,7)
  677. 1133. island chain in the western Atlantic and Caribbean region bordered by small carbonate platforms
    Antilles (USQRG:60,2,7)
  678. 1134. two carbonate platforms that border Florida
    Little Bahama Bank and Great Bahama Bank (USQRG:61,1,0)
  679. 1135. number of years ago the mid‐Jurassic time period occurred
    170 million (USQRG:61,1,1)
  680. 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)
  681. 1137. last time period in which the Bahama banks and southern Florida were part of the same carbonate platform
    Cretaceous (USQRG:61,1,1)
  682. 1138. distance below sea level some shallow‐water Jurassic deposits now lie near southern Florida
    10 kilometers (USQRG:61,1,1)
  683. 1139. main component of oolites
    ooliths (USQRG:61,1,2)
  684. 1140. ooliths
    spherical grains consisting of aragonite needles precipitated from seawater (USQRG:61,1,2)
  685. 1141. geological feature that piles ooliths into shoals
    strong currents (USQRG:61,1,2)
  686. 1142. type of bedding of oolith shoals in the Bahama banks
    cross‐bedding (USQRG:61,1,2)
  687. 1143. condition for individual ooliths to form
    ability for the ooliths to roll around (USQRG:61,1,2)
  688. 1144. stromatolites
    layered structures built up over a long time by cyanobacteria (USQRG:61,2,1; USQRG:103,1,12)
  689. 1145. How do cyanobacteria form sticky mats?
    trapping carbonate mud (USQRG:61,2,1)
  690. 1146. action of cyanobacteria after forming a stromatolite layer
    growing up through it (USQRG:61,2,1)
  691. 1147. time span of the fossil record of stromatolites
    3 billion years (USQRG:61,2,1)
  692. 1148. two types of environments in which stromatolites are almost exclusively found
    supratidal and high intertidal (USQRG:61,2,2)
  693. 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)
  694. 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)
  695. 1151. What feature allows large column‐shaped stromatolites to grow in some subtidal channels in the Bahamas?
    very strong currents (USQRG:61,2,2)
  696. 1152. country in which Shark Bay is located
    Australia (USQRG:61,2,2)
  697. 1153. two features of Shark Bay that make it conducive to stromatolites
    hypersaline waters and few animals (USQRG:61,2,2)
  698. 1154. land feature that mudcracks on coastal sands resemble
    mudcracks in a mud puddle that has dried up (USQRG:61,2,3)
  699. 1155. two types of environments indicated by mudcracks in ancient marine deposits
    intertidal or supratidal (USQRG:61,2,3)
  700. 1156. approximate time period that geologists recognized turbidity currents had produced certain sedimentary rocks
    mid‐20th century (USQRG:61,2,4)
  701. 1157. turbidity current
    flow of dense, sediment‐charged water moving down a slope due to gravity (USQRG:61,2,4)
  702. 1158. geological feature in which turbidity currents were first noticed
    clear lakes (USQRG:61,2,5)
  703. 1159. From where are turbidity currents in clear lakes formed?
    muddy river water hugging the lake floor (USQRG:61,2,5)
  704. 1160. Philip Kuenen’s home country
    the Netherlands (USQRG:62,1,0)
  705. 1161. decade in which Philip Kuenen demonstrated turbidity currents can attain great speeds
    the 1930s (USQRG:62,1,0)
  706. 1162. two characteristics that help turbidity currents gain speed
    being heavily laden with sediment and moving down steep slopes (USQRG:62,1,0)
  707. 1163. maximum percentage increase in the density of turbidity currents due to the presence of sediment
    100% (USQRG:62,1,0)
  708. 1164. behavior of sediment suspended in a turbidity current
    act as part of the moving fluid (USQRG:62,1,0)
  709. 1165. effect of a flattening slope on a turbidity current
    slows and spreads (USQRG:62,1,1)
  710. 1166. type of sedimentary bed deposited by turbidity currents
    graded (USQRG:62,1,1)
  711. 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)
  712. 1168. turbidite
    graded bed deposited by a slowing turbidity current (USQRG:62,1,1)
  713. 1169. continental slope
    steeply sloped zone between the continental shelf and the ocean depths (USQRG:62,1,2; USQRG:101,2,1)
  714. 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)
  715. 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)
  716. 1172. feature formed by turbidity currents at the mouths of submarine canyons
    deep‐sea fans (USQRG:62,1,2)
  717. 1173. geological feature superficially resembling deep‐sea fans formed by turbidity currents
    alluvial fans (USQRG:62,1,2)
  718. 1174. type of rock most commonly found in the sandy portion of lithified turbidites
    greywacke (USQRG:62,1,4)
  719. 1175. typical thickness of a single turbidite
    a few centimeters (USQRG:62,1,4)
  720. 1176. maximum thickness of a single turbidite
    1 meter (USQRG:62,1,4)
  721. 1177. minimum thickness of a meandering‐river cycle
    2 or 3 meters (USQRG:62,1,4)
  722. 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)
  723. 1179. “sole marks”
    irregularities in the base of a lithified turbidite (USQRG:62,1,4)
  724. 1180. information about turbidity currents that sole marks reveal
    direction of water flow (USQRG:62,1,4)
  725. 1181. typical rate of sediment accumulation in the abyssal plain
    one millimeter per 1,000 years (USQRG:62,2,1)
  726. 1182. material that forms most sediment in the deep ocean
    clay (USQRG:62,2,1)
  727. 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)
  728. 1184. ocean with the most abundant supplies of clay due to the weathering of rocks from oceanic volcanoes
    Pacific (USQRG:62,2,1)
  729. 1185. pelagic sediment
    fine‐grained sediment that settles to the deep‐sea floor (USQRG:62,2,1)
  730. 1186. pelagic forms of life
    organisms occupying the water just above the deep‐sea floor (USQRG:62,2,1)
  731. 1187. two biologically produced sediments found on the deep‐sea floor
    calcium carbonate and silica (USQRG:62,2,2)
  732. 1188. calcareous ooze
    calcium carbonate sediment consisting of skeletons of single‐celled planktonic organisms (USQRG:62,2,2)
  733. 1189. relative grain size of calcareous ooze
    fine (USQRG:62,2,3)
  734. 1190. foraminifera
    amoeba‐like protozoans whose skeletons form calcareous ooze (USQRG:62,2,3)
  735. 1191. nannoplankton
    single‐celled floating algae that helps form tropical phytoplankton (USQRG:62,2,3)
  736. 1192. maximum depth of calcareous ooze
    approximately 4,000 meters (USQRG:62,2,4)
  737. 1193. Why does calcareous ooze not exist at depths of 8,000 meters?
    dissolves at great depths (USQRG:62,2,4)
  738. 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)
  739. 1195. siliceous ooze
    biologically formed silica sediment carpeting the ocean floor in certain regions (USQRG:62,2,5)
  740. 1196. two regions with siliceous ooze covering the deep‐sea floor
    those at high latitude and in the tropical Pacific (USQRG:62,2,5)
  741. 1197. two organisms that form siliceous ooze
    diatoms and radiolarians (USQRG:62,2,5)
  742. 1198. diatoms
    highly productive phytoplankton group found in non‐tropical waters (USQRG:62,2,5)
  743. 1199. radiolarians
    single‐celled planktonic protozoans related to foraminifera (USQRG:62,2,5)
  744. 1200. type of silica forming the skeletons of diatoms
    opal (USQRG:62,2,5)
  745. 1201. Why is it impossible to discern individual skeletons of diatoms and radiolarians?
    Opal tends to recrystallize. (USQRG:63,1,0)
  746. 1202. diatomaceous earth
    soft sediment that forms siliceous ooze before recrystallization (USQRG:63,1,0)
  747. 1203. substance found on ocean floors that is used as the abrasive in many scouring powders
    diatomaceous earth (USQRG:63,1,0)
  748. 1204. geological period in which diatoms first formed
    Mesozoic (USQRG:63,1,1)
  749. 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)
  750. 1206. annual monetary cost of landslides in the United States
    1.5 billion (USQRG:63,1,2)
  751. 1207. deaths caused annually by landslides in the United States
    25 to 50 (USQRG:63,1,2)
  752. 1208. type of damage that comprises most of the economic cost of landslides
    road (USQRG:63,1,2)
  753. 1209. maximum potential death toll of a landslide
    hundreds of thousands (USQRG:63,1,2)
  754. 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)
  755. 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)
  756. 1212. example of poor engineering exacerbating natural vulnerability to a landslide
    oversteepening a slope (USQRG:63,1,2)
  757. 1213. landslide
    earth materials moving rapidly under gravitational force (USQRG:63,2,1; USQRG:102,1,14)
  758. 1214. two types of movement typically involved in a landslide
    downward and lateral (USQRG:63,2,1)
  759. 1215. avalanche
    movement of snow and ice that is similar to a landslide (USQRG:63,2,1)
  760. 1216. number of lives lost annually to avalanches in the United States
    approximately 20 (USQRG:63,2,1)
  761. 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)
  762. 1218. criteria for a downslope movement of material to be classified as “hazardous”
    likely to threaten man‐made structures (USQRG:63,2,2)
  763. 1219. smallest volume of material that can be involved in a landslide
    1 boulder (USQRG:63,2,2)
  764. 1220. country in which the largest landslide on earth occurred prehistorically
    Iran (USQRG:63,2,2)
  765. 1221. dimensions of the largest landslide on earth
    14 kilometers wide by 19 kilometers long (USQRG:63,2,2)
  766. 1222. annual monetary cost of landslide damage to buildings and building sites in the United States
    approximately $500 million (USQRG:63,2,3)
  767. 1223. major California city near which Big Rock Mesa is located
    Malibu (USQRG:63,2,3)
  768. 1224. number of people killed annually in the United States by small flows and landslides
    approximately 25 (USQRG:63,2,4)
  769. 1225. number of people killed annually worldwide by landslides
    600 (USQRG:63,2,4)
  770. 1226. state in which the Kootenai River Valley is located
    Montana (USQRG:64,1,2)
  771. 1227. dam near the Kootenai River Valley whose construction started in 1967
    Libby (USQRG:64,1,2)
  772. 1228. major city near the Pierre Formation in the United States
    Denver, Colorado (USQRG:64,1,2)
  773. 1229. equipment needed to detect old landslides with the potential to reoccur
    aerial photography equipment with remote sensing techniques (USQRG:64,1,2)
  774. 1230. particular type of clay whose presence indicates natural instability
    swelling (USQRG:64,1,3)
  775. 1231. season in which movement of soil rich in silt‐to‐clay‐sized material occurs
    spring (USQRG:64,1,3)
  776. 1232. loess soil
    fine soil developed on fine wind‐blown material (USQRG:64,1,3)
  777. 1233. city in which 200,000 lives were lost in 1920 during a loess landslide
    Kansu, China (USQRG:64,1,3)
  778. 1234. event that destroyed the Roman city of Herculaneum in 79AD
    mudflow (USQRG:64,1,3)
  779. 1235. mountain overlooking the ancient city of Herculaneum
    Mount Vesuvius (USQRG:64,1,3)
  780. 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)
  781. 1237. general time period in which the Rissa Clay and Leda Clay formations were deposited
    late glacial periods (USQRG:64,1,3)
  782. 1238. orientation of planes of weakness in bedrock that indicates instability
    downslope (USQRG:64,1,4)
  783. 1239. schistosity
    platy and rod‐shaped minerals in metamorphic rocks (USQRG:64,1,4)
  784. 1240. joint orientation relative to slope direction that is vulnerable to landslides
    parallel (USQRG:64,1,4)
  785. 1241. state in which the Gros Ventre landslide occurred
    Wyoming (USQRG:64,1,4)
  786. 1242. South Dakota city near a Cretaceous landslide triggered by a plane weakness that dipped steeply downslope
    Rapid City (USQRG:64,1,4)
  787. 1243. country of the Vaiont Reservoir landslide
    Italy (USQRG:64,2,0)
  788. 1244. year in which the Vaiont Reservoir landslide occurred
    1963 (USQRG:64,2,1)
  789. 1245. immediate result of the 1963 landslide plunging into the Vaiont Reservoir
    a 300‐foot high wave (USQRG:64,2,1)
  790. 1246. number of deaths that occurred in the Vaiont Reservoir landslide
    3,000 (USQRG:64,2,1)
  791. 1247. four geological features near which landslides are particularly common
    stream banks, reservoir shorelines, large lakes, and seacoasts (USQRG:64,2,2)
  792. 1248. location that exemplifies of soft glacial sediment and slope undercutting
    shores of the Great Lakes (USQRG:64,2,2)
  793. 1249. state in which the 1959 Madison Canyon landslide occurred
    Montana (USQRG:64,2,3)
  794. 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)
  795. 1251. 1965 British Columbia landslide that covered Highway 3 with 130 million tons of debris
    Hope Mountain slide (USQRG:64,2,3)
  796. 1252. event that triggered a Brazil landslide that killed 600 people in 1967
    a three‐hour cloudburst (USQRG:64,2,4)
  797. 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)
  798. 1254. two geological events correlated by studies of the Canadian Rockies
    rainstorms and rockfalls (USQRG:64,2,4)
  799. 1255. type of season in which landslides are particularly abundant along the West Coast of North America
    rainy (USQRG:64,2,4)
  800. 1256. angle of repose
    maximum angle that can be measured on a slope when material is stable and at rest (USQRG:65,1,2)
  801. 1257. natural angle of repose of stable materials
    approximately 40° (USQRG:65,2,0)
  802. 1258. location of a 1966 flow of fine‐grained mine waste that killed 144 people
    Aberfan, Wales (USQRG:65,2,0)
  803. 1259. state in which a failed dam made up of coal mine wastes triggered a 1972 landslide
    West Virginia (USQRG:65,2,0)
  804. 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)
  805. 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)
  806. 1262. What action at the base of a slope can set the whole slope in motion?
    removal of material (USQRG:65,2,2)
  807. 1263. 2006 landslide that blocked California Highway 140 near the Merced River
    Ferguson Slide (USQRG:65,fig)
  808. 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)
  809. 1265. range of seasonal water level variations in flood‐control reservoirs in steep valleys
    more than 100 feet (USQRG:66,1,2)
  810. 1266. season in which flood‐control reservoirs in steep valleys lower quickly
    spring (USQRG:66,1,2)
  811. 1267. mass wasting
    downslope movement of materials (USQRG:66,2,1)
  812. 1268. the most prevalent geologic process
    mass wasting (USQRG:66,2,1)
  813. 1269. creep (geologic process)
    mass wasting that is too slow to be detected by direct observation (USQRG:66,2,1)
  814. 1270. three manifestations of creep
    misaligned utility poles, out‐of‐plumb houses, and bulges in stone retainer walls (USQRG:66,2,1)
  815. 1271. analogy used by Nuhfer to illustrate the process of mass wasting and creep
    melting of a snowman (USQRG:67,1,0)
  816. 1272. Why do more landslides occur in spring?
    Soils are wet from recently melted snow. (USQRG:67,1,1)
  817. 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)
  818. 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)
  819. 1275. maximum speed of massive landslides
    upwards of 100 miles per hour (USQRG:67,1,3)
  820. 1276. most infrequent type of land‐wasting events
    massive landslides involving hundreds of tons of material (USQRG:67,1,3)
  821. 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)
  822. 1278. sturzstorm
    landslide involving billions of cubic yards of material (USQRG:67,1,4)
  823. 1279. California region with evidence of a sturzstorm
    Shasta (USQRG:67,1,4)
  824. 1280. planet that contains evidence of sturzstorms
    Mars (USQRG:67,1,4)
  825. 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)
  826. 1282. relationship between size and frequency of a landslide
    the larger the landslide, the more infrequently it occurs (USQRG:67,2,0)
  827. 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)
  828. 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)
  829. 1285. three topographic features examined during a complete geologic investigation of an area
    relief, steepness, and shape of slope (USQRG:67,2,3)
  830. 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)
  831. 1287. two soil features examined during a complete geologic investigation of an area
    type and thickness (USQRG:67,2,5)
  832. 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)
  833. 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)
  834. 1290. two vegetation features examined during a complete geologic investigation of an area
    amount and types present on the slope (USQRG:67,2,8)
  835. 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)
  836. 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)
  837. 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)
  838. 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)
  839. 1295. three roles of geologists at the regional level
    data gatherers, compilers, and organizers of basic information (USQRG:67,2,14)
  840. 1296. federal government body in charge of geological surveys
    U.S. Government Survey (USQRG:67,2,14)
  841. 1297. job scope of geologists employed by state geological surveys
    construct geological and slope stability maps (USQRG:67,2,14)
  842. 1298. main source of information for mapping completed by geologists
    field study of soils and rock formations (USQRG:67,2,14)
  843. 1299. two types of remote sensing photography that aid geologists in mapping
    satellite and high‐altitude (USQRG:68,1,0)
  844. 1300. factor of safety
    quantitative estimation of slope safety (USQRG:68,1,1)
  845. 1301. prerequisite of most engineering design projects involving construction on a sloping terrain
    calculating of a factor of safety (USQRG:68,1,1)
  846. 1302. two professions that make use of slope stability research
    mining and civil engineering (USQRG:68,1,1)
  847. 1303. country supporting a vigorous research program studying massive earth movements
    Russia (USQRG:68,1,2)
  848. 1304. How does the use of computers affect factor of safety calculations?
    faster and less tedious results (USQRG:68,1,3)
  849. 1305. science most essential to understanding good land use, according to Nuhfer
    geology (USQRG:68,1,5)
  850. 1306. Why should citizens understand slope hazards, according to Nuhfer?
    Many homes and developments are built on slopes. (USQRG:68,1,5)
  851. 1307. fraction of civil engineers who take at least one geology course before graduation
    one‐half (USQRG:68,2,0)
  852. 1308. year in which one of the most expansive landslides in history occurred near Thistle, Utah
    1983 (USQRG:68,2,1)
  853. 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)
  854. 1310. newspaper whose reporter coined the term Dust Bowl
    Washington Evening Star (USQRG:68,2,2)
  855. 1311. total cultivated land in the United States in the 1930s, in acres
    530 million (USQRG:68,2,3)
  856. 1312. type of crop most prevalent in the Great Plains in the 1930s
    cereal (USQRG:68,2,3)
  857. 1313. summer fallow
    only planting on cultivated land on alternate seasons (USQRG:68,2,3)
  858. 1314. fallow period
    time when a plot of land remains uncropped (USQRG:68,2,3)
  859. 1315. dust mulching
    process in which the soil is frequently clean tilled (USQRG:68,2,3)
  860. 1316. three purposes of dust mulching
    leave no crop residues on the surface, control weeds, and preserve moisture evaporation (USQRG:68,2,3)
  861. 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)
  862. 1318. two materials that are removed from topsoil during wind erosion
    silt and clay (USQRG:68,2,4)
  863. 1319. four states hit hardest by wind erosion during the Dust Bowl
    Texas, Oklahoma, Colorado, and Kansas (USQRG:69,1,1)
  864. 1320. westernmost state majorly affected by Dust Bowl wind erosion
    Montana (USQRG:69,1,1)
  865. 1321. group of Canadian provinces affected by the Dust Bowl wind erosion
    Canadian Prairie Provinces (USQRG:69,1,1)
  866. 1322. How did the Dust Bowl wind erosion make travel difficult?
    Airborne dust reduced visibility. (USQRG:69,1,1)
  867. 1323. general maximum amount of topsoil removed from some places during the Dust Bowl
    3 to 4 inches (USQRG:69,1,2)
  868. 1324. maximum height of dunes formed by topsoil during the Dust Bowl
    15 to 20 feet (USQRG:69,1,2)
  869. 1325. percentage of land affected by wind erosion in a Soil Conservation Service survey of 20 Dust Bowl counties
    80 (USQRG:69,2,0)
  870. 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)
  871. 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)
  872. 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)
  873. 1329. three methods of conservation tillage
    stubble mulch, mulch, and residue tillage (USQRG:70,1,0)
  874. 1330. crops used in a three‐year agricultural rotation
    wheat and sorghum (USQRG:70,1,0)
  875. 1331. areas in which a three‐year agricultural rotation is especially common
    humid regions in the West (USQRG:70,1,0)
  876. 1332. four states in 1982 with the most serious erosion per unit area
    Texas, Colorado, Nevada, and Montana (USQRG:70,1,1)
  877. 1333. three geological features that plagued the United States during the 1930s
    strong winds, drought, and clouds of dust (USQRG:70,1,2)
  878. 1334. percentage of the United States affected by the Dust Bowl
    nearly 75% (USQRG:70,1,2)
  879. 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)
  880. 1336. time period in which the seeds of the Dust Bowl were sown, according to Colenso
    early 1920s (USQRG:70,2,2)
  881. 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)
  882. 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)
  883. 1339. size of the 1931 United States crop compared to that of previous years
    record high (USQRG:70,2,2)
  884. 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)
  885. 1341. What event occurs if plow‐based farming is implemented in prairies?
    erosion of topsoil (USQRG:70,2,2)
  886. 1342. two characteristics of land without topsoil
    vulnerable to drought and inhospitable for growing crops (USQRG:70,2,3)
  887. 1343. black blizzards
    dust storms occurring in the Dust Bowl caused by drought and the loss of topsoil (USQRG:70,2,3)
  888. 1344. number of black blizzards reported in 1932
    14 (USQRG:70,2,3)
  889. 1345. number of black blizzards reported in 1933
    40 (USQRG:70,2,3)
  890. 1346. year the Dust Bowl ended due to the end of drought
    1939 (USQRG:70,2,4)
  891. 1347. tilling
    turning over the top layer of soil or removing weeds and adding fertilizers and pesticides (USQRG:70,1,3)
  892. 1348. soil nutrient that escapes topsoil during tilling
    carbon dioxide (USQRG:70,1,3)
  893. 1349. no‐till
    sustainable farming method that keeps nutrients in the soil (USQRG:70,1,3)
  894. 1350. location of organic matter in topsoil farmed with no‐till
    at the surface (USQRG:70,1,3)
  895. 1351. two processes reduced by the presence of healthy topsoil
    water runoff and erosion (USQRG:70,1,3)
  896. 1352. Okies
    nickname given to poor migrants from the Southwestern United States during the Dust Bowl (USQRG:71,1,1)
  897. 1353. percentage of Okies that actually came from Oklahoma
    approximately 20% (USQRG:71,1,1)
  898. 1354. fraction of Great Plains farmers who left their homes during the Dust Bowl
    one‐third (USQRG:71,1,1)
  899. 1355. state to which most migrating farmers during the Dust Bowl moved
    California (USQRG:71,1,1)
  900. 1356. United States president during the Great Depression and Dust Bowl
    Franklin D. Roosevelt (USQRG:71,1,3)
  901. 1357. year in which the first mortgage and farming relief act was passed under the New Deal
    1933 (USQRG:71,1,3)
  902. 1358. purpose of the first mortgage and farming relief act of the New Deal
    reduce foreclosures and keep farms afloat (USQRG:71,2,0)
  903. 1359. number of acres of United States farmland ruined by the end of 1934
    approximately 35 million (USQRG:71,2,0)
  904. 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)
  905. 1361. purpose of the 1934 Taylor Grazing Act
    designated 140 million acres as protected federal land (USQRG:71,2,1)
  906. 1362. two activities monitored on federal lands under the Taylor Grazing Act
    grazing and planting (USQRG:71,2,1)
  907. 1363. New Deal program known as the CCC
    Civil Conservation Corps (USQRG:71,2,1)
  908. 1364. time period in which the government created the CCC
    early 1930s (USQRG:71,2,1)
  909. 1365. number of young men who volunteered for work with the CCC
    3 million (USQRG:71,2,1)
  910. 1366. nickname for CCC workers
    Rooseveltʹs ʺForest Armyʺ (USQRG:71,2,1)
  911. 1367. three purposes of the CCC’s work
    control floods, conserve water, and prevent further soil erosion (USQRG:71,2,1)
  912. 1368. period in which the Farm Security Administration, Drought Relief Service, and Resettlement Administration were established
    between 1933 and 1935 (USQRG:71,2,2)
  913. 1369. New Deal program known as the WPA
    Works Progress Administration (USQRG:72,1,1)
  914. 1370. act under which the WPA was created
    Emergency Relief Appropriation Act (USQRG:72,1,1)
  915. 1371. number of people employed by the WPA
    over 8.5 million (USQRG:72,1,1)
  916. 1372. work completed by WPA employees
    construction of roads, bridges, airports, public parks, and buildings (USQRG:72,1,1)
  917. 1373. Black Sunday
    day on which million of tons of dirt from the Great Plains blew into Washington, D.C. (USQRG:72,1,2)
  918. 1374. government agency once known as the SCS
    Soil Conservation Service (USQRG:72,1,2)
  919. 1375. federal department that housed the SCS
    Department of Agriculture (USQRG:72,1,2)
  920. 1376. federal act that established the SCS
    Soil Conservation Act (USQRG:72,1,2)
  921. 1377. successor of the SCS
    Natural Resources Conservation Service (USQRG:72,1,3)
  922. 1378. two ideas promoted by the SCS
    healthy soil management and farming practices (USQRG:72,1,3)
  923. 1379. three SCS farming practices still used today in the Great Plains
    irrigation, crop diversity, and no‐till farming (USQRG:72,1,3)
  924. 1380. number of hectares of arid land in North America
    450 million (USQRG:72,1,4)
  925. 1381. percentage of arid land in North America that suffers moderate to severe desertification
    90 (USQRG:72,1,4)
  926. 1382. city in which NASAʹs Goddard Space Flight Center is located
    Greenbelt, Maryland (USQRG:72,1,6)
  927. 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)
  928. 1384. surface temperature of the Pacific Ocean relative to its average during the Dust Bowl
    cooler (USQRG:72,1,6)
  929. 1385. surface temperature of the Atlantic Ocean relative to its temperature during the Dust Bowl
    warmer (USQRG:72,1,6)
  930. 1386. large body of water with reduced moisture during the Dust Bowl due to abnormal ocean temperatures
    Gulf of Mexico (USQRG:72,2,0)
  931. 1387. the United Statesʹ major climatic event, according to Siegfried Schubert
    the 1930s drought (USQRG:72,2,1)
  932. 1388. identifying characteristic of La Niñas
    reduced Pacific Ocean surface temperatures (USQRG:72,2,2)
  933. 1389. type of conditions created in the Great Plains by La Niñas
    dry (USQRG:72,2,2)
  934. 1390. atmospheric general circulation model known as NSIPP
    NASAʹs Seasonal‐to‐Interannual Prediction Project (USQRG:72,2,3)
  935. 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)
  936. 1392. jet stream
    ribbon of fast moving air near the Earthʹs surface (USQRG:72,2,4)
  937. 1393. relative strength of the jet stream during the Dust Bowl
    weak (USQRG:72,2,4)
  938. 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)
  939. 1395. effect of the jet stream’s weakening on its travels
    travels farther south (USQRG:73,1,0)
  940. 1396. What soil characteristic can localize droughts, as confirmed by Siegfried Schubertʹs study?
    moisture levels (USQRG:73,1,1)
  941. 1397. type of process in which scarce rain leads to less evaporation, leading to even less rain
    feedback (USQRG:73,1,1)
  942. 1398. common factor in most major droughts of the United States in the 1900s
    cool tropical Pacific (USQRG:73,1,2)
  943. 1399. organization that funded Siegfried Schubertʹs study of the American climate over the past century
    NASAʹs Earth Science Enterprise (USQRG:73,2,0)
  944. 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)