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Name: _____________________________________________ ID: _________________
ENVIRONMENTAL GEOLOGY
FIRST MID TERM EXAMINATON
8 Pages
Time: 13:00 – 14:30
1:30 Hours
INSTRUCTIONS:
PLEASE read all instructions and
questions CAREFULLY and completely.
If you do not
understand a question as it appears on the exam, PLEASE ASK
FOR CLARIFICATION!!! It is to YOUR benefit to do so. This
examination is worth 15% of your semester grade.
Q1 _________
Q2 _________
Q3 _________
(33)
(13)
(24)
Total
70
 GOOD LUCK 
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Section 1
Multiple Choice
Circle the best answer
1. The ease with which fluids pass through a rock is determined by the rock’s
a. porosity.
b. permeability.
c. grain size.
d. age.
2. Which of the following would probably have the highest porosity?
a. sandstone
b. rock salt
c. granite
d. gneiss
3. A block on a dry, sloping surface is pulled downslope by ____________ and held in place
by friction.
a. pore pressure
b. elastic rebound
c. shearing stress
d. convection
4. Slopes may be oversteepened by
a. erosion by streams or waves.
b. tectonic deformation.
c. creation of roadcuts during construction.
d. all of the above
5. The vadose zone is the
a. zone of aeration.
b. saturated zone.
c. confined zone.
d. recharge zone.
6. The set of processes by which ground water is replenished is termed
a. discharge.
b. recharge.
c. saturation.
d. transpiration.
7. The most common minerals in the crust are
a. carbonates.
b. silicates.
c. sulfates.
d. sulfides.
8. Slow, gradual slip along a fault is termed
a. stress.
b. creep.
c. rebound.
d. focus.
9. Addition of water to soil on slopes may
a. stabilize the soil by freezing and thawing.
b. stabilize the soil by increasing pore pressure.
c. destabilize the slope by adding mass.
d. destabilize the slope by decreasing the slope angle.
10. An earthquake’s epicenter is
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a. the point of first break along the fault.
b. the line along which the fault moved.
c. the point on the earth’s surface directly above the focus.
d. the point on the far side of the earth, directly opposite the earthquake.
11. All of the following could increase the risk of landslide on a slope except
a. use of septic tanks.
b. building a house on the slope.
c. planting shrubs with extensive root systems.
d. adding fill at the top of the slope to build a road.
12. Vegetation may
a. increase slope stability because roots help hold soil in place.
b. decrease slope stability by adding weight.
c. increase slope stability by taking up moisture.
d. all of the above
13. Creation of a reservoir behind a dam
a. stabilizes the sides of the reservoir walls; the water buoys them up.
b. can destabilize the slopes by increasing pore fluid pressure.
c. destabilizes the slopes because of the weight of the dam.
d. has no effect on slope stability.
14. How well a concrete structure withstands an earthquake depends on
a. the basic design of the structure.
b. the length of the main shock.
c. the material on which the structure is built.
d. all of the above
15. The steepness or slope of a stream channel in the direction of flow is the channel’s
a. capacity.
b. bed load.
c. base level.
d. gradient.
16. Earthquake-related hazards include all of the following except
a. liquefaction.
b. landslides.
c. release of radon gas.
d. seismic sea waves.
17. The steepest stable slope that an unconsolidated material can maintain is the material’s
a. shear strength.
b. angle of repose.
c. cohesion.
d. scarp.
18. The principal source of evaporated water that becomes precipitation is
a. streams.
b. glacier ice.
c. the oceans.
d. volcanic eruptions.
19. Constructing a flood-control dam and reservoir
a. may incidentally make irrigation or hydropower generation possible.
b. may create a recreational facility.
c. will restrict navigation and fish migration along the stream.
d. all of the above
20. A hydrograph is
a. a plot of stream stage or discharge versus time.
b. a map showing the extent of a floodplain.
c. a diagram that illustrates flood recurrence intervals.
d. a graph of variations in precipitation through time.
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21. Tile drainage systems and city storm sewers
a. reduce flood hazards by removing water quickly.
b. have no effect on flood hazards; they do not drain into streams.
c. increase flood hazards by preventing infiltration.
d. reduce flooding where they are installed but may increase it along a stream into which the
discharge flows.
22. Strategies designed to reduce damage to structures in floodplains include
a. planting vegetation within the stream channel.
b. filling in land in the floodplain to reduce flood volume.
c. raising buildings on stilts to elevate floor levels.
d. all of the above
23. All of the following have been recognized as earthquake precursors except
a. changes in the ground’s surface tilt.
b. changes in frequency of seismic sea waves.
c. changes in electrical resistivity of rocks.
d. changes in radon content of well waters.
24. In designing a retaining wall to support an unstable slope, the best design would be
a. a high, thin, impermeable wall.
b. a high, thin wall with drainage holes.
c. a short, stout wall at the foot of the slope.
d. Any of these; all would be equally effective.
25. Which of the following is/are true?
a. Clay minerals make for very stable slopes because they bake and harden in the sun.
b. An unstable slope can be stabilized by removing material to reduce the slope angle.
c. Natural slopes, once formed, remain stable unless disturbed by human activities.
d. all of the above
26. Expansive clays
a. expand when wet, shrink when dried out.
b. make a good building foundation because they mold to the structure.
c. are economically useful sulfide minerals.
d. all of the above
27. The concept of the rock cycle is that
a. rocks are moved around the world by geologic processes.
b. rocks are continually undergoing change, being transformed into new rocks.
c. the world changes, but rocks are permanent.
d. rocks must be cycled deep into the crust to be made into different rocks.
28. Where abundant ground water percolates through limestones, ____________ may be
formed.
a. artesian wells
b. aquicludes
c. sinkholes
d. perched water tables
29. Limitations on the use of surface water as a water source include
a. basic lack of surface water in some regions.
b. seasonality of streamflow.
c. past use of some lakes and streams for dumping wastewater.
d. all of the above
30. Possible consequences of excessive groundwater withdrawal include
a. surface subsidence.
b. swelling of aquifer rocks.
c. increased permeability of aquifer rocks.
d. all of the above
31. Which of the following is an environmental problem in Oman?
a. Seawater intrusion.
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b. Galciation of higher trains.
c. Radio active wastes disposal.
d. All of the above.
32. Recharge of aquifers may be reduced by all of the following except
a. consumption of artesian well water.
b. the filling-in of a swamp for construction.
c. construction over the recharge area of a confined aquifer.
d. increasing the efficiency of surface runoff.
33. Use of water for irrigation
a. does not significantly affect groundwater consumption, as surface water is nearly always used.
b. could be increased by using desalinated water, which is cheap.
c. could be more efficient with drip irrigation.
d. all of the above
Section 2 (13 points)
True or False Statments
Put T or F in front of the question number.
34. Muscat is subject to landslides.
35. The physical properties of a mineral are often closely related to its internal atomic
arrangement, or crystal structure.
36. The height of the potentiometric surface is a measure of the pressure on the water in a
confined aquifer; it is the height to which the water’s pressure will raise the water in a well
drilled into that aquifer.
37. If the rate of groundwater withdrawal exceeds the rate of recharge, regional water tables
may be lowered.
38. Mass wasting threatens only property, not lives, because it occurs so slowly.
39. Treated wastewater can be recycled for irrigation or even as drinking water to extend water
supplies.
40. During flooding, stream velocity typically decreases because the larger volume of water
encounters more friction from the sides of the stream channel.
41. The removal of vegetation usually makes soil-covered slopes more stable because it
removes excess weight.
42. The basic “building blocks” of the silicate minerals are tetrahedra of silicon and carbon.
43. Saltation is a process by which streams dissolve soluble minerals and become saltier.
44. The most accurate flood-frequency curves can be constructed by selecting short sets of data
for particularly high-discharge periods in a stream’s history.
45. Most human activities tend to reduce flood hazards, so the frequency of floods of a given
size has been decreasing for nearly all streams.
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46. Use of dams to create reservoirs for water supply may conflict with the flood-control
functions of the dam/reservoir system.
Section 3 (22 points)
Fill in the blank & Questions:
47. A ________________ zone is a region of deeper earthquake foci where geometry reflects a
subducting slab of lithosphere.
48. A basin designed to hold surplus surface runoff, keeping it out of a stream, is__________
49. An ________________ is a rock that is low in permeability, so water does not readily pass
through it.
50. The main water sources in Oman are __________ & ________________ .
51. Addition of a little moisture to dry soil may improve its _____________.
52. Landslides may be triggered by ______________ or by heavy rains.
53. A rock sample was immersed in water till it was fully saturated. Then weighed to give a
total mass of 700 g. The sample is then dried in the oven and weighed to give a mass of
400g. If the total volume of the sample is 1000 cm3, calculate the porosity of the rock. (3.5
points)
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54. List the types of plate boundaries. (1.5 points)
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55. Describe two strategies for protecting an inhabited area from an advancing lava flow. (3
points)
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56. Describe two precursor phenomena that may precede volcanic eruptions. (3 points)
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57. The graph below is a flood frequency curve for the Aljari River for 41 years. From the
graph answer the following: (7 points)
Discharge (Mm3/day)
1400
1200
1000
800
600
400
200
0
1
10
100
Recurrence Interval (years)
a- What is the extrapolated flood in 100 years? (Show your work)
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b- If the river floods its bank every 10 years, at what discharge will the river floods its bank?
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b- If the river floods its bank every 10 years, what will be the probability of a flood to occur each
year?
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d- If the river cross section is a semi circle of 40m, calculate the velocity in meter per second at
600 Mm3/day discharge.
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GOOD LUCK
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