FieldTrip Lab Worksheet Complete
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Long Beach City College *
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Course
160L
Subject
Geography
Date
Dec 6, 2023
Type
docx
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3
Uploaded by CoachMusic12933
ERTH 160L
Name: Lorelai Burke
Virtual Field Trip—Alamitos Bay
Purpose:
This lab will introduce you to the sand source for Long Beach and Huntington Beach beaches
and the processes that move the sand around. We will then take a virtual tour via GoogleEarth
to explore the differences between beaches along Alamitos Bay and beaches toward the open
water. Along the way, we will introduce ocean salinity. Salinity will be explored more in the
future.
Part I. Material and movement along the beach.
1a. What do you think might happen if the river stops bringing new sand to the beach?
Beaches and coastlines will narrow and even disappear.
1b. In the slide with two white arrows, which direction is longshore drift
A
/ B
(Circle one)
1c. How do you know? (Explain)
Because the sand is being plucked and deposited, you can tell by the amount of sand of either
side of the wall, and how there is more sand on the left side because the sand is being pushed
towards the wall.
Part 2: Salinity
Salinity of water is a measure of how much dissolved salts there are. In the oceans, salinity is
measured in parts per thousand (ppt or ‰). PPT means that for every 1 salt molecule there are
999 water molecules (i.e., one in a thousand). Parts per hundred (or percent or %)
Looking at the salinity map, answer the following questions.
2a. Where is salinity highest?
The Atlantic Ocean, the Mediterranean Sea – mid-latitudes
2b. Where is it lowest?
Near the Poles – glacier run off is salt free.
3. If a body of water has a salinity of 37 ppt, what is the percentage of salt? (Show calculation)
37/10 =
3.7 %
What are some processes that could increase salinity? Decrease salinity?
Increase – evaporation!
Decrease – precipitation/glacier runoff!
Are there places other than those on the map where you would expect salinity to be higher?
Lower?
Not other than the places it states on the map.
Part 3. Virtual Fieldtrip
Click the link
https://earth.google.com/earth/rpc/cc/drive?state=%7B%22ids%22%3A%5B
%221XjbVEDc9zMGi7eNCGjyKdTiMG5GQZ8dJ%22%5D%2C%22action%22%3A%22open%22%2C
%22userId%22%3A%22110127186209009525891%22%7D&usp=sharing
3. The first stop is at Alamitos Bay on the side of the peninsula.
a.
What is the salinity of the water?
37 ppt, or 3.7%
b.
Is this higher or lower than the average?
Higher than average
How would you describe the wave energy and size?
Waves are small and have no energy or merely do not exist.
What do you think is the relationship between wave energy, sand grain-size and shell
types and size?
Smaller waves mean less energy, which means smaller sediments are carried, meaning most
seashells and sand grains are relatively small on the bay side.
c.
Given the salinity value, what processes and conditions are there in the bay?
I would suspect a good amount of evaporation happens at the bay, leaving more salt in there
4. Second stop is the Long Beach Harbor side of the peninsula.
a.
What is the salinity of the water?
34 ppt or 3.4%
b.
Are the sand grains larger or smaller than on the Alamitos Bay side?
Larger, as the waves are bigger and have more energy, allowing bigger sediments to be
carried.
What might salinity tell you about conditions in the nearly open harbor?
It could show us how much runoff or precipitation that area is getting, and how safe
conditions are for people and animals
5. Looking at the whole peninsula
a.
Describe: What do you notice about the shape and size of the beach?
There is more sand the more northwest you go, and less the further down in the southeast
direction on the harbor side. This I suspect is because of longshore drift, which is pushing
more sand towards the left side of the peninsula.
If you had a home on the beach somewhere in this view, where would you think it
would be safest or most exposed to storm surge, large waves or sea-level rise?
I feel it would be safer on the side of the peninsula that it getting sand pushed towards it, this
creates more space between you and huge waves or riding sea level.
In the pictures, can you see how the waves are hitting the beach and which way they
would move the sand? Where do you think the trucks are taking the sand from and
bringing it to? Why?
They are moving the sand up northwest in the peninsula, to the left side.
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