Dana Point Harbor Virtual Field Trip (2)
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School
Santiago Canyon College *
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Course
27243
Subject
Geography
Date
Dec 6, 2023
Type
Pages
4
Uploaded by JudgeFogQuetzal30
Dana Point Harbor Virtual Field Trip
Name: Cedric Cervantes
Key Topics: Weathering, Erosion, Coastlines, Geologic Structures, Geologic Hazards and Mitigation
Instructions: Answer the following questions using your textbook and the two links below. Click
or copy & paste each link into a separate window of your internet browser:
1) Using your own words, write the definition for each term below. Then choose the type of coastline
each feature is most likely to be found.
Headland (Depositional/Erosional): A headland is a piece of land that stick out onto a body of
water that typically has a rocky shore
Sea Cliff (Depositional/Erosional): A sea cliff is a steep vertical shaped cliff like structure that borders
Water, a huge rock wall
Baymouth Bar (Depositional/Erosional): Sedimentary structure that forms across an entrance to
a bay
Sea Arch (Depositional/Erosional): A sea arch is the result of wave erosion and is a natural rock
formation
Barrier Island (Depositional/Erosional): A long low lying piece of land that is parallel to the main
shore
and are typically made up of sand
Wave-cut Platform (Depositional/Erosional):
A flat area found at the base of shoreline or sea
Sea Stack (Depositional/Erosional): An other natural rock structure created by wave erosion, formed
vertically with visible layers of erosion
2) Find Dana Cove on the geologic map, then look at the photographs on the Blog. Does this area
resemble a Depositional or Erosional coastline? Explain your answer using the appropriate terms
from the previous question.
Dana cove would likely resemble a erosional coastline due to the headland like structure that it
is as well as well as other features like its wave cut platform and sea cliffs
3) Zoom into the cliffs along Dana Cove on the geologic map Using the map legend, list the names of
the three main rock types found in the cliffs and give a brief description of each.
Sandstone:
Sandstone is a sedimentary rock that has minerals and is typically composed
of quartz, feldspar, and other minerals
Siltstone:
Siltstone is a sedimentary rock that forms through the compaction and cementation
of silt, which consists of mineral particles
Gravel:
Gravel is a type of unconsolidated sedimentary rock that forms through the natural
processes of erosion, transportation, and deposition
4) Now find Dana Point on the geologic map. What coastline feature does this resemble? Using the
scale at the bottom, estimate how far Dana Point has receded (Hint: look underwater). What other
features are remnants related to the erosion of Dana Point?
The coastline feature that this resembles is a headland and using the scale at the
bottom we can indicate that Dana Point has receded about 39 miles from its original
point. Some other features related to the erosion of Dana Point are the sea cliffs and
stacks
5) According to the Blog, what was being built at the top of the cliffs containing Capistrano Formation
in the 1920s? What halted construction? What two structures are the only remnants of this building?
So In the 1920’s, Sidney Woodruff wanted to build a Dana Point Inn on the top of the
cliffs but the Depression interfered with the construction which halted it and all that's left
of the Inn are the concrete arches and the tunnel
6) Looking at the photo of the tunnel on the Blog, what geologic process can be measured using the
distance between the tunnel opening and the base of the cliff?
The distance between the tunnel opening and the base of the cliff could be the geologic
process of Erosion. Over time, wind, water, and other natural forces can erode the cliff
causing it to recede as well as measuring the distance from the tunnel opening to the
base of the cliff at different points in time, you could sorta estimate the rate of erosion
7) According to the Blog, what manmade structure was built just off the coast (in the ocean) around
1971 to create the Dana Point Harbor? What are the pros and cons of this type of structure?
The man made structure that was built off the coast during 1971 to create the Dana Point
Harbor was a set of breakwaters. Some pros are protection against waves as well as help to
prevent Beach Erosion but some cons are controversies surrounding the impact it has on the
natural environment as well as the POSSIBILITY of beach erosion.
8) Using the geologic map, what geologic structure separates the San Onofre Breccia from the
Capistrano Formation in the cliffs above Dana Cove? (Hint: Look for the dotted line where the road
has been built going up the cliff)
The Dana cove vault
9) According to the Blog, what was also built around 1971 directly on top of this geologic structure
(from the question above) at the edge of the cliff? Was this a good idea? Explain your answer.
Something that was also being built around the time was a restaurant called The Quiet
Cannon. I don’t think this was a good idea because It's almost waiting for something
bad to happen considering its placement on the cliff.
10) What geologic hazard occurred beneath the restaurant in 1980? What factors do you think
triggered this hazard? Name at least one possible natural and one possible man made trigger.
The geological hazard that occurred beneath the restaurant was a landslide. One
natural trigger is the sole fact that the foundation the building was relying on consists of
pebbles, as well as the weight of the building on the edge of the cliff, overtime will
eventually slide off. I think one man made trigger was the entire operation of even
building this restaurant, knowing it wasn’t a good idea at the time, they still went with it.
11) What engineering measures has the County since taken to ensure this hazard does
not continue to further jeopardize the restaurant and everything below?
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An engineering process they did was remediation. So they built a crib wall at the bottom
of the cliff and a concrete structure at the top of the cliff, which is held in place by
greater than 100 foot long rock anchors
12) In early Spring 2018, a small rockfall occurred in the same location as the previous landslide.
What was the likely trigger of this mass wasting event?
I think it was triggered by a combination of natural weathering processes and human
activity considering the amount of time that went by between the years 1980 and 2018
13) Do you think the County’s measures are a permanent solution? Explain your answer
I think it's a solution at the moment but permanent….? I don’t think so, I say this
because we’ve seen what natural disasters/geological processes took place overtime
meaning its only safe for us to assume that as time goes by, they’ll only take place
again