# 5.11: Student Responses

1. What type of stream drainage pattern is present on this map? This may be easier to determine by examining the tributaries to the main stream.

a. dendritic                         b. trellis                         c. radial                         d. rectangular

2. Based on the drainage pattern type, does the bedrock underlying this area consist of rocks uniformly resistant to erosion or rocks alternating between resistant and non-resistant layers?

a. uniformly resistant bedrock                              b. alternately resistant and non-resistant bedrock

3. Are the rocks likely tilted and folded or horizontal?

a. tilted and folded                                             b. horizontal

4. Are streams in this area downcutting or laterally eroding?

a. downcutting                                                   b. laterally eroding

5. In which stage of the cycle of stream erosion is this area?

a. old age                            b. mature                      c. youthful

6. Calculate the stream gradient of Grape Creek in ft/mile. Use the index contour just above the “m” in Temple Canyon for your initial spot. Measure the gradient to the index contour past the word Creek (the last contour before it reaches Arkansas River). The distance between these areas is ~1.6 miles (measured along the curving distance of the non-magnified stream). What is the gradient?

a. 15’/mile                         b. 100’/mile                         c. 125’/mile                         d. 200’/mile

7. Observe the stream on the Omaha N, Nebraska-Iowa quadrangle. In which stage of the cycle of stream erosion is this area?

a. old age                         b. mature                             c. youthful

8. Compare the contour intervals from the Royal Gorge, Colorado map (map 5.1) to the Omaha N, Nebraska-Iowa map. Would you expect the gradient of the Missouri River in Nebraska to be greater or less than the gradient that you calculated for the Grape River in Colorado?

a. less than the Grape River gradient                              b. greater than the Grape River gradient

9. Locate the state boundary between Nebraska and Iowa along the Missouri River. Why does the boundary depart from the river channel?

a. When the boundary was created, Iowans wanted the Carter Lake area in their state.

b. The boundary follows the course of the river at the time that it was drawn; the river has since moved.

c. None of the above

10. What is the term for the geologic feature called Carter Lake?

a. entrenched meander                         b. oxbow lake                         c. cutbank                         d. point bar

11. Was Carter Lake cut off before or after the state boundary between Nebraska and Iowa was drawn?

a. before                                             b. after

12. On which date did a flood event have a recurrence interval of 0.5?

a. 2/27/2013                         b. 10/13/2009                         c. 3/10/2011                         d. 4/20/2015

13. Of the following dated flood events, which one would you expect to happen more often?

a. 8/27/2008                         b. 2/24/2013                           c. 2/6/2010                          d. 12/23/2013

14. Observe your best fit line. What approximate discharge would be associated with a 50-year recurrence interval?

a. 2,000 cfs                           b. 4,750 cfs                             c. 8,500 cfs                         d. 14,000 cfs

15. Flood stage, or bankfull stage, on Sweetwater Creek occurs at a discharge of ~4,500 cfs. According to your best fit line, what is the recurrence interval of such a discharge?

a. 0.5 years                           b. 3 years                               c. 25 years                          d. 50 years

16. During the flood event of 9/23/2009, the discharge measured at this gaging station was 21,200 cfs. Note where this would plot on your graph. Would the recurrence interval for this flood plot at:

a. 100 years                          b. 300 years                            c. 700 years                        d. longer than 1,000 years

17. Is it possible that a flood with a similar discharge to that of the event from 9/23/2009 could happen again in the next 20 years?

a. Yes                                   b. No

18. Which gas station is the most likely source of the gasoline leak?

a. Station A                         b. Station B                         c. Station C

19. Is the school likely to be at risk of contamination from this same leak?

a. Yes                                b. No

20. Is the church likely to be at risk of contamination from this same leak?

a. Yes                                b. No

21. Locate Little Sinking Creek in the southern portion of the map, north of Hwy. 68 and south of the Edmonson County Line. In which direction does it flow?

a. South                         b. North                         c. Southeast                         d. Northwest

22. Follow the creek along its path. Where does it wind up?

a. Along Hwy. 68            b. It disappears underground.

23. Find Sloans Crossing. It is south of Mammoth Cave. What is the benchmark elevation at Sloans Crossing?

a. 600’                           b. 630’                           c. 800’                                d. 834’

24. Now, look farther south of Sloans Crossing at Hwy. 31W. Look closely at the topography south of the highway as it changes abruptly. What feature(s) can you observe south of Hwy. 31?

a. Sinkholes                         b. Disappearing streams                         c. Generally lower land surface elevations                         d. All of the above

25. Keeping the abrupt topography change in mind, which of the following is true? a. In the northern portion of the map, the area is underlain by limestone b. In the southern portion of the map, the area is underlain by limestone 26. Locate the Louisville and Nashville Railroad line just south of Hwy. 31. Would this be an easy location to maintain a railroad?

a. Yes                             b. No

26. Locate the Louisville and Nashville Railroad line just south of Hwy. 31. Would this be an easy location to maintain a railroad?

a. Yes                             b. No

27. How would one describe this river?

a. Straight                         b. Meandering                         c. Low sinuosity                         d. Braided

28. In this stream, erosion is occurring on the ______________ because _______________, while deposition is occurring on the _____________________ because ______________________.

a. point bars; the fastest velocity water flows to this point; cut banks; the slowest velocity water flows to this point

b. point bars; the slowest velocity water flows to this point; cut banks; the fastest velocity water flows to this point

c. cut banks; the fastest velocity water flows to this point; point bars; the slowest velocity water flows to this point

d. cut banks; the slowest velocity water flows to this point; point bars; the fastest velocity water flows to this point

29. How would one describe this river?

a. Straight                         b. Meandering                         c. Low sinuosity                         d. Braided

30. What factors control the course of this river?

a. Steep gradient and high discharge                                 b. Low gradient and low discharge

c. Low gradient and abundant sediment supply                   d. Steep gradient and low sediment supply

31. The river in this area has a rather particular pattern, what geologic process caused this?

a. a meander eroded through its bank and created an oxbow lake

b. the river is in a karst terrain and disappeared into the ground

c. the river is following patterns, likely faults, in the underlying bedrock

d. during a flood the river breached the natural levee flowing into the floodplain

32. Zoom out and examine the surrounding area, what geological hazards are likely in the area?

a. sinkholes                         b. flooding of urban areas                         c. erosion and subsidence                         d. none of the above

Search for 41 24 30.77N 122 11 46.23W and zoom to an eye altitude 50,000 feet.

33. What type of drainage pattern is present in this area?

a. Trellis                             b. Dendritic                                              c. Rectangular                                         d. Radial                                           e. Deranged

34. What does this type of drainage pattern indicate about the area?

a. rocks in the area are homogeneous and/or flat-lying                              b. rocks in the area are alternating resistant and non-resistant, forming parallel ridges and valleys

c. stream channels radiate outward like wheel spokes from a high point      d. stream channels flow randomly with no relation to underlying rocks or structure

35. What type of drainage pattern was present in this area?

a. Trellis                             b. Dendritic                                              c. Rectangular                                         d. Radial                                           e. Deranged

36. What does this type of drainage pattern indicate about the area?

a. rocks in the area are homogeneous and/or flat-lying                              b. rocks in the area are alternating resistant and non-resistant, forming parallel ridges and valleys

c. stream channels radiate outward like wheel spokes from a high point      d. stream channels flow randomly with no relation to underlying rocks or structure

37. In what direction was the main river flowing?

a. West                             b. East                             c. North                             d. South

38. How were these lakes formed?

a. they were man-made – all are dammed                                                                  b. they are formed by large rivers in the area

c. as sinkholes, as underlying soluble rock was dissolved and areas collapsed                 d. they are impact structures that filled with water

39. What type of bedrock is present in this area?

a. Limestone                             b. Sandstone                              c. Gneiss                                    d.Granite                                 e. Chert

40. These features you are seeing are linear valleys. Assume that water flowed through these valleys at some time. What type of drainage pattern would this area represent?

a. Trellis                             b. Dendritic                                              c. Rectangular                                         d. Radial                                           e. Deranged

41. Think about the drainage pattern you selected in the previous answer – what does this tell you about the underlying rocks?

a. The rocks are probably fractured.

b. The rocks are uniformly resistant.

c. The rocks are part of a topographic high, like a mountain.

d. The rocks are alternately resistant and non-resistant In the Search tab, type in Warrego Valles and zoom to ~120 miles.

42. Notice the general shape of this feature. It is thought to have formed by the runoff of either precipitation or groundwater. What type of drainage does this appear to be?

a. Trellis                             b. Dendritic                                              c. Rectangular                                         d. Radial                                           e. Deranged

For maps with higher quality, use the link below and go to page 124:

https://web.ung.edu/media/university-press/Laboratory%20Manual%20for%20Introductory%20Geology%20Updated%20082817.pdf?t=1510260756287