MARINE GEOLOGY EXAM #1 – Fall 2008
FIGURES ARE ON THE LAST PAGES
General directions:
READ the questions carefully and write your answers in complete sentences. Answers should focus
on the question – don’t ramble! I am looking for a few sentences to get to the point. Be sure your
answers answer the questions – reread the questions! Students lose so many points b/c they do not
actually answer the question, or they don’t fully answer all the parts to a question.
You will answer a total of 6 questions, so time yourself accordingly. Be succinct!!
For all of the air photos on the attached pages, assume that north is the top of the page.
Answer 2 of the following 3 questions (15 points each)
1. If the moon had never formed (or, perhaps it flew out of orbit), would we have tides?
Explain why or why not.
Depending on your answer above, answer one of the following:
 If so, how would Charleston’s tides differ from those we have today?
 If not, what type of delta would occur at Breach Inlet?
2. Explain how a marginal flood channel forms on the downdrift side of a tidal inlet. Include a diagram
that illustrates the wave crests and longshore transport directions.
3. Sketch a beach profile from the primary dune to the offshore that you would expect to find on a
prograding barrier island a couple of months after a major storm. Label the features on the profile
and indicate where mean high tide (HT) and mean low tide (LT) occur.
Indicate what type of profile is depicted.
Answer 1 of the following 3 questions (10 points)
4. Give a generic (i.e., not a specific place) example of a Primary Coast and a Secondary Coast.
Explain why each would be classified as such.
5. Explain what information ripples on a beach provide and give an example.
Draw a map view of the ripple in your example.
6. Explain why sediments migrate onshore as a wave transitions to a shallow water wave.
Include a diagram.
You must answer the next question (20 points)
7. Review Figure 1. The left panel has letters A-N that you may wish to use as reference points in your
answers (e.g., “erosion between K and L….”). You do not have to use these letters.
a) In what direction is the overall longshore transport? What is your evidence?
b) What is the longshore transport direction at letters A and G? What is your evidence?
c) Based on the back-barrier setting, do you think this barrier island is typical of those off the
Charleston coast? Why or why not?
d) What type of barrier island is this? Justify your answer. (Note: this should be the longest part of
your answer!)
MARINE GEOLOGY EXAM #1 – Fall 2008
Answer 1 of the following 2 questions (15 points)
8. Review Figure 2 of the updrift end of Dewees Island.
a) What is the dark feature just south of A (on the beach)? How was this formed?
b) Describe what is occurring in this figure. Identify features shown at or near the letters.
c) Explain how sand located at C could eventually migrate to the area between A and D.
9. Compare Figures 3 and 4 of two inlets from other parts of the U.S. coast.
a) Are these two inlets from shorelines that are tide-dominated, wave-dominated or mixed-energy?
Cite your evidence/observations to support your interpretation for each inlet.
b) Describe what you would expect to see in the type of inlet that is NOT represented here.
You must answer the next question (25 points)
10. Figure 5a shows the area surrounding the Edisto River and its associated tidal delta. The river itself
does not contribute much sediment to the nearshore area, so most of the sediment is derived and
transported from tidal and wave influences. In other words, the river mouth is very much like a large
tidal inlet. Note the location of Kiawah Island, which we have studied in some detail. Only the
recurved spit is shown in the photo. This spit is a small fraction of the total island.
Botany Bay Island is on the southwest side of the inlet. Figure 5b is a close-up of the inlet throat
area and nearby features. A portion of BBI’s long, narrow beach is shown on the left edge of the air
photo image. Fig. 5c shows a beach similar to the beach along BBI indicated by letter A on 5a.
To write your answers, you may use the abbreviations indicated on Figure 5a.
a) Hypothesize the origin of Deveaux Bank (DB). Explain your reasoning for this hypothesis.
b) What type of barrier island is Botany Bay Island (BBI)? What is your evidence?
c) Note the offset between the two islands. What is the probably cause of the offset?
Is this typical or atypical of the barrier islands along the central SC coast?
d) If you cored through the beach on the left edge of Figure 5b (or on the beach in the above photo),
what would you encounter? Compare this core to a similar core taken on the beach of Kiawah.
Be sure to check that you have answered 6 questions,
and that you’ve answered each part of each question.
FIGURES ARE ON THE NEXT PAGES
MARINE GEOLOGY EXAM #1 – Fall 2008
Fig. 1
Fig. 2
MARINE GEOLOGY EXAM #1 – Fall 2008
Fig. 3
Fig. 4
MARINE GEOLOGY EXAM #1 – Fall 2008
Fig. 5a
Fig. 5b
MARINE GEOLOGY EXAM #1 – Fall 2008
Fig. 5c