These questions should give you an idea of the kind of thinking I am after, and the way the questions may be structured. Answers to the questions, along with the reasoning, are given at the bottom of this page. I suggest that you try to take this exam without looking at the answers -- then check and see how you've done. When you miss a question, use my explanations to help figure out where you went wrong.
4. In the block diagram below
a. the strike of the bed is E&endash;W and the dip is N b. the strike of the bed is E&endash;W and the dip is S c. the strike of the bed is N&endash;S and the dip is E d. the strike of the bed is N&endash;S and the dip is W e. the strike of the bed is N and the dip is S
Questions 5 through 9 refer to the geologic map below5. Which bed is the oldest?
a. pCm b. Dm c. Pl d. Tsh e. there is no way to tell from this map
6. Which bed is the youngest?
a. pCm b. Dm c. Pl d. Tsh e. there is no way to tell from this map
7. Are there any unconformities evident on the map?
a. yes, between pCm and Dm only b. yes, between pCm and Dm, and between Tsh and all the rocks it is in contact with c. yes, between Dm and Mss only d. no, all the beds are conformable e. there is no way to determine the answer from this map
8. What sort of geologic structure do the Paleozoic beds form?
a. a monocline b. a syncline plunging SW c. a syncline plunging NE d. an anticline plunging NE e. an anticline plunging SW
9. Some speculators are forming the Silver River Oil Exploration Company. Their land is shown on your geologic map. You wonder if you should buy in. After looking at the map and applying your geologic expertise, you decide:
a. There are likely source and reservoir rocks, and a good trap. b. Although there are possible source and reservoir rocks, there is no trap. c. There is no trap, and there are no possible source or reservoir rocks. d. There is a likely source rock and a trap, but no reservoir rocks e. There is no way to decide from the map
Look at questions 10-14 in the sample 1st midterm
15. Where would you most expect to find large normal faults?
a. mostly in the central areas of continents
b. in places where lithospheric plates are sliding by one other
c. in areas of strong crustal extension or stretching such as
on mid-oceanic ridges or in uparched continental areas
d. in areas of crustal shortening such as fold-mountain belts
and subduction zones
e. mostly in volcanic arcs
16. Ores of heavy metals (such as copper, lead, zinc, gold, silver,etc.)
are most commonly found
a. in sandstones and silts deposited in shallow marine (shelf) environments b. in shales deposited in swamps c. in association with hot springs and igneous or metamorphic rocks d. in stream gravels e. in association with strike&endash;slip faults
17. You find a layer of coal exposed in a roadcut. Which one of the following rocks
would be most likely to be lying above it (on top of it)?
a. shale b. greywacke c. mica schist d. coarse angular conglomerate e. basalt
18. Match the each of the dune types listed with the conditions appropriate
for its formation.
____unidirectional wind, ample sand supply A. barchan
____unidirectional wind, limited sand supply B. parabolic dune
____bidirectional strong winds, limited sand supply C. star dune
____winds from many directions D. transverse dune
____partially vegetated or downwind of blowout E. longitudinal (linear) dune
The correct matching order is:
a. DAECB b. EBACD c. EBCDA d. ACEBD e. CDBAE
19. An itinerant earthquake prophet warns you that a giant earthquake is going to occur and "the entire West
Coast - back to Salt Lake City - will disappear under the sea like Atlantis." Are you worried? (Is this
possible?)
a. Yes, seismic studies have shown that large areas on continental crust occur on the deep-sea floor b. Yes, because there is an active subduction zone offshore pulling the continent down c. No, because continental material is less dense than oceanic material and both are "floating" on denser viscous mantle d. No, because a vast amount of mantle material would have to move quickly out of the way and the mantle is too viscous to respond that rapidly e. answers (c) and (d) are both correct
20. A seismograph records a P-wave arrival at 9:15 a.m. and an S-wave arrival at 9:25 a.m. Use the diagram
below to find the distance from the seismograph to the earthquake epicenter. The distance is:
a. 2000 km
b. 4000 km
c. 7000 km
d. 10,000 km
e. 12,000 km
21. The two seismograms below were recorded at different stations during an earthquake. The stations happened to be
close enough to the epicenter to undergo noticeable shaking. Which of the following statements are true?
(mark True or False as you go, then choose answer.) The arrows indicate the wave arrivals.
____A was further from the epicenter than B
____the earthquake magnitude was greater at B than at A
____the earthquake intensity was greater at B than at A
____station A is probably located on bedrock, B is on natural or artificial fill
The proper matching order is
a. TTFF
b. FFTT
c. FTFT
d. TFTF
e. FTTF
22. If the paleomagnetic direction recorded in a lava flow was vertically upward, where
on the globe would the rock have formed?
a. 45 degrees south latitude
b. 45 degrees north latitude
c. south pole
d. north pole
e. equator
Answers (with reasoning):
4. d (The direction of dip is the direction the bed slopes-- i.e., the downslope
direction of the bedding surface. The strike is at right angles to the dip
direction. Refer to text and lab manual.)
5. a (You need to know the geologic time scale. Precambrian rocks are older than
all the rest)
6. d (To answer questions 5 and 6, you simply have to know the order of the periods
in the geologic time scale from oldest to youngest. You can look this scale
up in your text or lab manual. Precambrian rocks are the oldest ones in our
time scale; the Tertiary period is the youngest period but one, ending about
2 my ago.)
7. b (If you know the time scale, you can see that the rocks representing the
older Paleozoic rocks, i.e.those of the Cambrian, Ordovician, and Silurian
periods are missing; while all the rocks of the Mesozoic i.e., the Triassic,
Jurassic, and Cretaceous periods are absent. The Tertiary shale sits with
angular unconformity on the younger Paleozoic rocks.)
8. b (The overall pattern of the Paleozoic beds indicates an eroded plunging fold.
The youngest Paleozoic rocks -- i.e., the Permian limestone -- are in the
center of the fold, proving that it's a syncline [downfold]. A syncline
opens out in the direction of plunge. The fold patter here clearly opens
to the SW.)
9. b (The Devonian marine sediments are a possible source rock, and the
Mississippian sandstones are a possible reservoir rock. However there is
no trap: a syncline won't trap the oil, and there is also no caprock in the
Silver River area.)
10-14 (Plate tectonics questions. See sample midterm 1.)
15. c (Normal faults cause extension of the crust, hence are found especially in
areas of crustal stretching.)
16. c (Ores of heavy metals are typically associated with hot or once-hot rocks.
They are formed especially by hydrothermal alteration, contact metamorphism,
and sometimes magmatic segregation.)
17. a (Coals are laid down in swampy environments; clays (shale) and river or beach
sands are the most likely other sediments to be deposited in these areas.)
18. a (No reasoning here -- just knowing the conditions under which each dune type
forms.)
19. e (to make the whole west coast sink below the ocean in an earthquake would require
the rapid moving out of the way of a vast amount of viscous mantle material -- which
is physically impossible. Also continental crust is of lower density, making it hard
to submerge large areas of it in the mantle.)
20. c (the difference in the S and P arrival times is 9:25 - 9:15 = 10 min. Search the
travel-time graph to find where the S and P curves are 10 min apart. The distance where
the curves are separated by this amount is 7000 km. Specifically, at 7000 km the S-wave
curve crosses the 20 min line and the P-wave curve crosses the 10 min line, so the
difference in arrival times in 10 min.)
21. b (the distance between the P and S arrivals is the same for both seismograms, so the
two stations are the same distance from the epicenter; since the stations are recording
the same earthquake, the magnitude is the same at both stations; the amplitude (height)
of the seismograms indicates the amount of ground motion & shaking, so station B
experiences the greater intensity, probably because it's on some sort of fill, while
station A, which doesn't shake near as much, is on bedrock)
22. c (the lines of magnetic force point vertically upward at the south pole)