Chapter 7 Smartworks Activity Answers

1. Identify geologic structures that can result from rock deformation. Label the geologic structure in each photograph. a. (top left, bottom left, top right, bottom right) Joint, Fold, Fault, Foliation 2. Match the three faults with their respective names. a. (Top to bottom) reverse fault, thrust fault, normal fault 3. Distinguish attributes of crustal deformation as being associated with folding or faulting. a. Folding: compressional stress, bending of geologic materials, ductile deformation b. Faulting: brittle deformation 4. Order the steps in continental collision. a. 5. Label the diagram depicting the characteristics of a collisional orogen. a. (left to right) undeformed sedimentary rock, fold-thrust belt, suture, metamorphic rock 6. Identify where igneous, metamorphic, and sedimentary rocks would be found on the image of a mountain below. a. Igneous rocks, metamorphic rocks, sedimentary rocks 7. Using the Isostasy: The Basics topic of the Isostasy Simulation, experiment with variables that affect isostasy. Identify how the variables increase or decrease the block root—the amount of block that resides below the liquid level. a. Increased Block Root: increased block thickness, increased block density b. Decreased Block Root: increased liquid density, decreased block thickness 8. Identify the location of the craton in North America on the image below by selecting the appropriate letter for the location from the dropdown box. a. B 9. Sideling Hill, in western Maryland, is a northeast-southwest-trending ridge underlain by Paleozoic sandstone, shale, and coal. This fold formed due to the collision of Africa with North America. Note that the compass shown over on the highway points approximately north. Drag each of the labels so it overlies the appropriate target. The trace of a marker horizon is shown in purple. Remember that "dip" refers to the angle that a layer makes relative to the horizontal. a. (left to right) southeast-dipping limb, fold hinge zone, northwestdipping limb, terrace out 10. This image shows a fault exposed at the Yellow Mounds overview in Badlands National Park. Please label each fault block with the appropriate term. a. (left to right) footwall block, hanging-wall block 11. Compare dip-slip and strike-slip faults. Sort the properties into the appropriate categories. a. Dip-slip faults: results in crustal lengthening or shortening, crust is shortened or lengthened b. Strike-slip faults: associated with shear stress, motion is primarily horizontal 12. Match each type of strain taking place to the corresponding image of a cube and fossil shell. Red arrows indicate the stress acting on the cube and shell. The terms provided refer to changes in the horizontal direction. a. (top to bottom) Unstrained, stretching, shortening, shear strain 13. The bare-earth LiDAR imagery showing the Tahoe-Sierra frontal fault zone indicates that this fault is most likely a ______ a. Dip-slip, normal 14. Sort attributes according to whether they are associated with faulting or folding. a. Faulting: earthquakes, fracturing, brittle deformation b. Folding: ductile deformation 15. This picture of a fault shows the top of two distinctive marker beds, which have been highlighted with purple and yellow lines. Drag the labels to the appropriate targets. a. (top to bottom) hanging wall, fault, footwall 16. At locality F along the fault, place the labels indicating which side of the fault has older rocks and which has younger rocks. a. (top to bottom) older, younger 17. Watch the Introduction to the Faults Animation found here, and label the following fault components on the diagram. a. 18. Label the features on the illustration of a subduction zone. a. 19. Label the diagram of a convergent-margin orogen. a. (left to right) incoming exotic terrane, active accretionary prism, active arc, suture, pluton, fold-thrust belt 20. Sort these mountain chains based on what caused them to form. a. Continental Collision: Alps, Himalayas, Appalachian Mountains b. Other Causes: Rocky Mountains 21. Sort outcomes related to either an increase in erosion or an increase in mountain building. a. Mountain Building: Continental crust thickens, Asthenosphere is compressed, Lithospheric mantle sinks lower b. Erosion: Continental crust thins