Coastal Hazards.F22.ONLINE-2
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School
College of Charleston *
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Course
103L
Subject
Geology
Date
Dec 6, 2023
Type
Pages
6
Uploaded by UltraEnergy6947
1
•
You will need:
o
Internet
o
Laboratory Manual for Introductory Geology,
Chapter 17 Shorelines
o
The PowerPoint slides presentation on OAKS
Environmental Geology 103L
Name
COASTAL PROCESSES
PART 1: How Coasts Form
A.
Materials from which coasts are made:
Watch this video and answer the following questions:
https://www.youtube.com/watch?v=pxmHHoTPSKI
1.
Which mineral comprises the sand on most beaches?
2.
Where does sand come from?
3.
How is the sediment that becomes sand transported to the coast?
4.
Why are most beaches made of sand and not large pebbles? (Hint: think energy of transportation!)
5.
Why are silt and clay deposited offshore and not on the beach?
6.
When rock is weathered and becomes sediment it is called (Circle one):
EROSION
or
DEPOSITION
7.
When that sediment settles out (ex. on the beach) it is called (Circle one):
EROSION
or
DEPOSITION
8.
Are ALL beaches made of the mineral Quartz?
9.
If not, what are some examples of where sand on other beaches comes from?
10.
.
Below, identify which image belongs to which sediment type: SAND, SILT/CLAY, or PEBBLES:
a. _____
_
b. ____
_
c. ______
2
Below, name where you think each type of sediment from the above pictures would be deposited: RIVER, BEACH, or
DEEP OCEAN. Then indicate WHY it would settle there, by picking the energy level where it is deposited:
11.
.
IMAGE a from #10.
a.
WHERE would it settle out (pick one)?
RIVER
BEACH DEEP OCEAN
b.
WHY (pick one)? HIGH ENERGY
MEDIUM ENERGY LOW ENERGY
12.
.
IMAGE b from #10.
a.
WHERE would it
settle out (pick one)?
RIVER
BEACH DEEP OCEAN
b.
WHY (pick one)? HIGH ENERGY
MEDIUM ENERGY LOW ENERGY
13.
.
IMAGE c from #10.
a.
WHERE would it settle out (pick one)?
RIVER
BEACH DEEP OCEAN
b.
WHY (pick one)? HIGH ENERGY
MEDIUM ENERGY LOW ENERGY
B.
What determines the shape and features of a coast?
15.
See
LAB CHAPTER 17 SHORELINES
Section 17.2 on pg.432-433
of your manual. What force dominates shoreline
erosion?
16.
What controls this force?
17.
What other factors can have a profound effect on shorelines?
18.
See
Fig.17.1 on pg.433
of your manual. Which shoreline do you think was formed by glaciers during the last ice age?
19.
See
Section 17.3.1 on pg. 444
of your manual. How do waves form?
Watch this video and answer the following questions:
https://www.youtube.com/watch?v=U9EhVa4MmEs
20.
Do waves approach the shoreline parallel to the beach?
21.
How does the wave angle of approach move sand along a beach?
22.
What is longshore drift?
23.
See
Section 17. 2.5 on page pg. 437
of your manual. Answer the following:
a.
What causes long-terms sea-levelchanges?
b.
What is a submergent shoreline?
c.
What are some features of a submergent shoreline?
d.
What is an emergent shoreline?
e.
What are some features of an emergent shoreline?
3
24.
Plate tectonics also play an
important role in shaping
Earth’s shorelines. Look at
the Plate Tectonic World
map and compare the
southeast coast of the US
to the northwest coast of
the US, and answer the
following:
a.
What is the plate tectonic setting of the NW US, such as WA (pick one)? CONVERGENT, DIVERGENT, or
NOT NEAR A PLATE BOUNDARY
b.
What is the plate tectonic setting of the SE US, such as SC (pick one)? CONVERGENT, DIVERGENT, or NOT
NEAR A PLATE BOUNDARY?
c.
Which would you expect to have an emergent shoreline and WHY?
PART 2: Features of a Submergent Coastline
1.
What are the main features of a barrier island system? Use
Figure 17.16 on pg. 451
of your manual to
describe the following:
a.
Barrier Island-
b.
Spit-
c.
Marsh-
2.
Inlets are extremely important when it comes to the coastal environment. Looking at
Figure 17.16 on pg.
451
, what do you conclude an inlet is?
3.
Tides have a great influence on shaping our coasts. Use
Section 17.2.3 page 434
in your manual and the
link below to answer the following:
https://oceanservice.noaa.gov/education/tutorial_tides/tides02_cause.html
a.
What causes tides?
To answer b. and c., click on the
“Frequency
of tides
”
link located on the right side of this page.
b.
How many low tides per day do most coastal areas (including SC) have?
c.
How many high tides per day do most coastal areas (including SC) have?
4.
See
Figure 17.3 on pg. 436
of your lab manual and read the paragraph below
Figure 17.3
. What is the
difference in sea levels at this location in France between low and high tide?
5.
Look at
SLIDE 1
,
“
Tidal Deltas
”
, in the
Coastal images PowerPoint (located on OAKS
).
a.
Think about high tide moving water land-ward through an inlet. How do you think a flood tidal delta is
formed? (Hint: think about all you have learned about the energy of water and deposition)
b.
Think about low tide moving water out ocean-ward through an inlet. How do you think an ebb tidal
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4
delta is formed?
6.
Look at
SLIDE 2
, “
Washover Fans
”
, in the Coastal Images PowerPoint.
a.
Washover fans consist of beach sand, but you can see they are found towards the marsh side of a
barrier island. How do you think a washover fan forms?
b.
What do you think the existence of a washover fan(s) indicates about that particular barrier island?
c.
What do you think happens to a barrier island if washover fans occur frequently on an already eroding
barrier island (Hint: the sand from the beach side of the barrier island is being moved towards the
marsh side of the island, without equal sand replacing it!)?
7.
The process you described above is called
barrier island rollover
.
Washover fans are often the result of typical
storms. Therefore, hurricanes can have an even more drastic effect. You can see rollover happen as a result of
Hurricane Katrina in the images on this page (at the bottom):
http://www.nasa.gov/vision/earth/lookingatearth/katrina_poststorm.html
In which direction did the island rollover towards?
8.
Watch this video and answer the following:
https://www.youtube.com/watch?v=5W3_y5_3w9A
a.
How do dunes form?
b.
How does vegetation help form dunes?
c.
Dunes are the first line of defense in the event of a storm. What do humans commonly do to interrupt
this process?
PART 3: Coastal Issues
As we explore what is being done to combat shifting beaches, keep the following in mind:
•
Coastal environments are dynamic, constantly in flux.
•
Seasonal changes occur due to late summer/fall hurricanes and winter storms. These storm events often have
devastating results as barrier islands buffer our main coastlines from the storm energy and therefore receive the
brunt of the storm.
1.
So why learn to identify the features and characteristics of coastal environments? Use the following two
websites to answer the questions below:
http://oceanservice.noaa.gov/facts/population.html
http://asbpa.org/2017/02/14/invest-in-our-coastal-infrastructure/
a.
Go to the top link (NOAA). How many people live in counties directly on the shoreline (2014)?
b.
What percentage of the
nation’s
population is that?
c.
Click on the second link and read the 5
th
paragraph down. Beaches help generate how much money per
year for the national economy?
d.
The federal government spent $44 million in 2012 on beach nourishment (adding sand to beaches). How
many billions did they receive in return in from tax revenue?
5
2.
Examine
SLIDE 3
,
“
Erosion on the south end of Folly Beach
”,
in the
Coastal Images PowerPoint
. Answer
the following:
a.
On the South end of Folly Beach, are
there any areas labeled as “Low”
for coastalerosion
(BVI=Beachfront Vulnerability Index, determined by NOAA)?
b.
Are there areas labeled high? If so where?
c.
Compare the Folly erosion map to
SLIDE 4
,
“
Coastal Erosion in the United States
”. Is the erosion on
Folly
unusual?
d.
Which areas in the country have higher rates of coastal erosion than the Charleston area?
3.
See
Figure 17. 1 on pg.433
of your lab manual.
a.
Which of these shorelines do you think would be the most difficult to erode?
b.
Which do you think would be the easiest?
4.
Use
Section 17.5 pgs.359-369
to answer the following questions:
a.
Besides tsunamis, what are the two ways shorelines can become natural disaster areas?
b.
What are the three ways hurricanes can cause damage? (
See Section 17.5.2, pages 460-465
)
c.
What is a storm surge?
d.
What was the storm surge for hurricane Katrina in 2005?
e.
See
Fig.17.27 on pg. 465
. What percentage of New Orleans was flooded as the result of levee breaks
from Hurricane Katrina?
Part 4: Using Topographic Maps to compare two US coastlines
Using the “
Point Reyes Quadrangle”
topographic map (on OAKS), answer the following:
1.
What is the contour interval of this map?
2.
On southern part of the map find Point Resistance, along Drakes Bay. Imagine you hike from the beach at Point
Resistance to the letter “G” in “RIDGE.” Answer the following:
a.
What is the elevation at the
“G”
in RIDGE?
b.
What is the vertical change of your hike (assuming an elevation of
0’
at the start of your hike)?
c.
Using a ruler, measure the distance from Point Resistance to the G in RIDGE and record it here.
d.
What is the gradient of your hike? _____ ft/mi
3.
On southern part of the map find Point Resistance, along Drakes Bay. The blue lines are similar to contour lines
but are depth below sea-level instead of above. Using the scale at the bottom of the map and a ruler, what is the
depth ~1 mile off shore? (
Pick one of the following
)
a.
Between 12 and
18’
b.
Between 18 and
30’
c.
Between 30 and
60’
d.
Greater than
60’
4.
Do you see a marsh on this map?
6
5.
Are the rivers on this map more so STRAIGHT or MEANDERING?
6.
Would you classify this as an EMERGENT or SUBMERGENT coastline?
Using the
“James Island Quadrangle”
topographic map on OAKS, answer the following:
7.
What is the contour interval of this map?
8.
Find the word
“FOLLY”
on the western side of folly beach. Imagine you hike from the beach near the word
“FOLLY”
(elevation
0’)
to the
“B”
in
“Folly
Beach”
just inland from it. Answer the following:
a.
What is the elevation at the
“B”
in Folly Beach?
b.
What is the vertical change of your hike (assuming an elevation of
0’
at the start of your hike)?
c.
Using a ruler, measure the distance from the beach to the B in Folly Beach and record it here.
d.
What is the gradient of your hike? _____ ft/mi
9.
Measure 1 mile from the coastline of Folly Beach at the word
“FOLLY”
out into the Atlantic Ocean. What is the
depth here? (
Pick one of the following
)
a.
Between 0 and
6’
b.
Between 6 and
12’
c.
Between 12 and
18’
10.
Which coast, South Carolina or California, has a steeper gradient when going from the coast out to sea?
11.
Do you see a marsh on this map?
12.
Are the rivers on this map more so STRAIGHT or MEANDERING?
13.
Would you classify this as an EMERGENT or SUBMERGENT coastline?
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