Stream Morphology
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Students will construct a physical scale model of a stream system
to help understand how streams and rivers shape the solid earth
(i.e., the landscape). Students will perform several experiments
to determine streamflow properties under different conditions.
They will apply the scientifc method, testing their own scenarios
regarding human impacts to river systems.
• Design a stream table model to analyze the different
characteristics of streamflow.
• Explain the effects of watersheds on the surrounding
environment in terms of the biology, water quality, and economic
importance of streams.
• Identify different stream features based on their geological
formation due to erosion and deposition.
• Develop an experiment to test how human actions can modify
stream morphology in ways that may, in turn, impact riparian
Time Requirements
Preparation……………………………………………………………. 5 minutes,
then let sit overnight
Activity 1: Creating a Stream Table ………………………….. 60 minutes
Activity 2: Scientifc Method: Modeling Human Impacts
on Stream Ecosystems……………………………. 45 minutes
2 Carolina Distance Learning
Personal protective
goggles gloves apron
link to
results and
warning corrosion flammable toxic environment health hazard
Table of Contents
2 Overview
2 Outcomes
2 Time Requirements
3 Background
9 Materials
10 Safety
10 Preparation
10 Activity 1
11 Activity 2
12 Submission
12 Disposal and Cleanup
13 Lab Worksheet
17 Lab Questions
A watershed is an area of land that drains
any form of precipitation into the earth’s water
bodies (see Figure 1). The entire land area that
forms this connection of atmospheric water to
the water on Earth, whether it is rain flowing into
a lake or snow soaking into the groundwater, is
considered a watershed.
Water covers approximately 70% of the earth’s
surface. However, about two-thirds of all water
is impaired to some degree, with less than
1% being accessible, consumable freshwater.
Keeping watersheds pristine is the leading
method for providing clean drinking water to
communities, and it is a high priority worldwide.
However, with increased development and
people flocking toward waterfront regions to live,
downstream communities are becoming increasingly polluted every day.
From small streams to large rivers (hereafter
considered “streams”), streamflow is a vital
part of understanding the formation of water
and landmasses within a watershed. Understanding the flow of a stream can help to determine when and how much water reaches other
areas of a watershed. For example, one of the
leading causes of pollution in most waterways
across the United States is excessive nutrient
and sediment overloading from runoff from
the landmasses surrounding these waterways.
Nutrients such as phosphorus and nitrogen
are prevalent in fertilizers that wash off lawns
and farms into surrounding sewer and water
systems. This process can cause the overproduction of algae, which are further degraded
by bacteria. These bacteria then take up the
surrounding oxygen for respiration and kill
multiple plants and organisms. A comprehensive understanding of the interaction between
streams and the land as they move downstream
to other areas of a watershed can help prevent
pollution. One example is to build a riparian
buffer—a group of plants grown along parts of
a stream bank that are able to trap pollutants
and absorb excessive nutrients; this lessens the
effects of nutrient overloading in the streambed.
(A riparian ecosystem is one that includes a
stream and the life along its banks.)
Sediment, which is easily moved by bodies of
water, has a negative effect on water quality. It
can clog fsh gills and cause suffocation, and the
water quality can be impaired by becoming very
cloudy because of high sediment flow. This can
create problems for natural vegetation growth
by obstructing light and can prevent animals
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Figure 1.
Background continued
from visibly fnding their prey. Erosion also has
considerable effects on stream health. Erosion,
or the moving of material (soil, rock, or sand)
from the earth to another location, is caused by
actions such as physical and chemical weathering (see Figure 2). These processes loosen
rocks and other materials and can move these
sediments to other locations through bodies
of water. Once these particles reach their fnal
destination, they are considered to be deposited. Deposition is also an important process
because where the sediment particles end up
can greatly impact the shape of the land and
how water is distributed throughout the system
(see Figure 2). Erosion and deposition can occur
multiple times along the length of a stream and
can vary because of extreme weather, such
as flooding or high wind. Over time, these two
processes can completely reshape an area,
causing the topography, or physical features, of
an entire watershed to be altered. Depending on
weather conditions, a streambed can be altered
quite quickly. Faster moving water tends to
erode more sediment than it deposits. Deposition usually occurs in slower moving water. With
less force acting on the sediment, it falls out
of suspension and builds up on the bottom or
sides of the streambed.
Sediments are deposited throughout the length
of a stream as bars, generally in the middle of
a channel, or as floodplains, which are more
ridgelike areas of land along the edges of the
stream. Bars generally consist of gravel or sandsize particles, whereas floodplains are made of
more fne-grained material. Deltas (see Figure
3) and alluvial fans (see Figure 4) are sediment
deposits that occur because of flowing water
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Figure 2. Figure 3.
Erosion Deposition
and are considered more permanent structures because of their longevity. They are both
fan-shaped accumulations of sediment that
form when the stream shape changes. Deltas
form in continuous, flowing water at the mouth
of streams, whereas alluvial fans only form in
streams that flow intermittently (when it rains
or when snow melts). Alluvial fans are usually
composed of larger particles and will form in
canyons and valleys as water accumulates in
these regions. The fan shape of both deposits
is easy to spot from a distance, because they
are formed due to the sand settling out on the
bottom of the streams.
Streamflow Characteristics
Discharge, or the amount of water that flows
past a given location of a stream (per second),
is a very important characteristic of streamflow. Discharge and velocity (the speed of
the water moving in the stream) are both vital
to the shaping of streambeds. Within stream
ecosystems, there are microhabitats (smaller
habitats making up larger habitats) that have
different discharges and velocities. The type
of microhabitat depends on the width of that
part of the stream, the shape of the streambed,
and many other physical factors. In areas that
contain rifes, water quickly splashes over
shallow, rocky areas, which are easily observed
in sunny areas (see Figure 5). Deeper pools of
slower moving water also form on the outside
of the bends of the streams, as shown in Figure
5. Runs, which are deeper than rifes but have
a moderate current, connect rifes and pools
throughout the stream. The source of a stream
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Figure 4.
Figure 5.
Rifes Pool
Background continued
is where it begins, while the mouth of a stream is
where it discharges into a lake or an ocean.
Flow rate is very helpful for engineers and
scientists who study the impacts of a stream
on organisms, surrounding land, and even
recreational uses such as boating and fshing.
The speed of the water in specifc areas helps
to determine the composition of the substrate
in that area of the streambed, i.e., whether the
material is more clay, sand, mud, or gravel.
Particle sizes of different sediments are shaped
and deposited throughout various areas of a
stream, depending on these factors.
Most streams have specifc physical features
that show periodicity or consistency in regular
intervals. Meanders can occur in a streambed
because of gravity. Water erodes sediment to
the outside of a stream and deposits sediment
along the opposite bank, forming a natural
weaving or “snaking” pattern. This pattern can
form in any depth of water and along any type
of terrain. Sinuosity is the measure of how
curvy a stream is. This is a helpful measurement
when determining the flow rates of streams
because it can show how the curves affect the
water velocity. In major rivers and very broad
valleys, meanders can be separated from the
main body of a river, leaving a U-shaped water
body known as an oxbow lake (see Figure 6).
These lake formations can become an entirely
new ecosystem with food and shelter for some
organisms, such as amphibians, to thrive in.
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Figure 6.
Oxbow Lake Formation
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Another feature important for streamflow is the
difference in elevation, or the relief of a stream
as it flows downstream. Streams start at a
higher elevation than where they end up; this
causes the discharge and velocity at the source
versus that at the mouth of the stream to be
quite different, depending on the meandering
of the stream and the type of deposition and
erosion that occurs. The gradient is another
important factor of stream morphology. This
is a measure of the slope of the stream over
a particular distance (the relief over the total
distance of the stream). For a kayaker who
wants to know how fast he/she can paddle
down a particular stream, knowing the difference
in elevation (relief) is important over a particular
area; however, knowing the slope of this particular area will give the kayaker a more accurate
prediction. With erosion and deposition occurring at different rates and at different parts of the
stream, knowing the gradient is a very important
part of determining streamflow for the kayaker.
Groundwater is also affected by changes in
the stream shape and flow. Water infltrates the
ground in recharge zones. If streams are continuously flowing over these areas, the ground is
able to stay saturated. Most streams are perennial, meaning they flow all year. However, a
drought or an extreme weather event may lower
the stream level. This can lower the groundwater level, which then allows the stream to only
sustain flow when it rises to a level above the
water table. With the small amount of available
freshwater on Earth, it is vital that our groundwater sources stay pristine.
Biotic and Economic Impacts of Streams
Not only are streams a major source of clean
freshwater for humans, but they are also a
hotspot for diversity and life. There is great biotic
variability between the different microhabitats
(e.g., rifes, pools, and runs) of a stream. Rifes,
in particular, have a high biodiversity because of
the constant movement of water and replenishment of oxygen throughout. Pools usually have
fewer and more hardy organisms in their slower,
deeper moving waters where less oxygen is
available. There are also a multitude of plant
and animal species living around streams. From
a stream in a backyard to the 1,500-mile-long
Colorado River, streams have thousands of
types of birds, insects, and plants that live near
them because they are nutrient-rich with clean
freshwater. Sometimes nutrient spiraling can
occur in these streams. Nutrient spiraling is the
periodic chemical cycling of nutrients throughout
different depths of the streams. This process
recycles nutrients and allows life to thrive at all
depths and regions of different-size streams.
Streams can also have signifcant economic
impacts on a region. Streams are a channel for
fshing and transportation, two of the largest
industries in the world. Because of all the
commercial boating operations that occur worldwide in these channels, it is vital to understand
the formation and flow patterns of streams so
that they are clear and navigable. Fishing for
human consumption is another large, worldwide
industry that depends on stream health; keeping
streams pristine and understanding how they
form are of utmost importance in sustaining this
top food industry. Recreational activities such
as kayaking, sportfshing, and boating all shape
areas where streams and rivers are prevalent as
Background continued
All acts that happen on land affect the water
quality downstream. Through creating a model
stream table in this lab, one can predict large,
system-wide effects. Many land features and
physical parts of a streambed can affect the flow
of water within a watershed. Houses along a
streambed or numerous large rocks can cause
the streamflow to change directions. If any of
these factors cause erosion or deposition in
an area of the stream, microhabitats can be
created. These factors can affect the stream on
a larger scale, creating changes in flow speeds
and widths of the streambeds.
The Importance of Scaling and the Use of the
Scientifc Method
When a stream table model is created, a largescale depiction of a streambed is being reduced
to a smaller scale so that the effects of different
stream properties on the surrounding environment can be demonstrated. While the stream
table made in this lab is not a to-size stream
and landscape, the same processes can be
more easily observed at a scaled-down size.
Scientists frequently create models to simplify
complex processes for easier understanding.
For example, to physically observe something
that is too big, such as the distance between
each planet in the solar system, the spatial
distance can be scaled to create a solar system
model. By changing the distance between each
planet from kilometers to centimeters, this large
system is now more feasibly observed. Similarly,
the stream model allows us to physically view
different scenarios of a streambed and analyze
different stream properties. Mathematical
equations are also used frequently to observe
data to predict future conditions, such as in
meteorological models. Ultimately, models can
be very important tools for predicting future
events and analyzing processes that occur
in a system.
When one creates a model, many different
outcomes for the same type of setup can be
possible. In this case, multiple variations of
similar-size streambeds will be designed to
evaluate different stream features and their
impacts on the surrounding ecosystem. When
performing any type of scientifc evaluation, the scientifc method is very useful in
obtaining accurate results. This method involves
performing experiments and recording observations to answer a question of interest.
Although the exact step names and sequences
sometimes vary a bit from source to source,
in general, the scientifc method begins with
a scientist making observations about some
phenomenon and then asking a question. Next,
a scientist proposes a hypothesis—a “best
guess” based upon available information as to
what the answer to the question will be. The
scientist then designs an experiment to test the
hypothesis. Based on the experimental results,
the scientist then either accepts the hypothesis
(if it matches what happened) or rejects it (if it
doesn’t). A rejected hypothesis is not a failure; it
is helpful information that can point the way to
a new hypothesis and experiment. Finally, the
scientist communicates the fndings to the world
through presenting at a peer-reviewed academic
conference and/or publishing in a scholarly
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journal like Science or Nature, for example.
When creating stream table models, we are
trying to understand how different factors can
affect streamflow. A few very important steps
from the scientifc method are required. The frst
is forming a testable hypothesis, or an educated
prediction, of what you expect to observe
based on what you have learned about stream
morphology thus far. In Activity 1, the steps are
already listed, so the main goal is to compare
the two differences in stream reliefs. However,
in Activity 2, the goal is to alter a different variable and predict what will happen to several
stream features in this new situation. In general,
when recording these observations to test a
hypothesis, it is important to repeat the tests.
To obtain valid results, you need to have similar
results over multiple attempts to ensure consistency in the fndings and to show that what you
are discovering is not by chance but is instead
replicated each time the experiment is run. While
multiple trials are not required in this lab experiment, if you feel particularly less than confdent
with your results from doing only one trial run in
Activity 1 or 2, feel free to do multiple trials to
test for validity.
Needed but not supplied:
• Tray or cookie sheet (or something similar)
• 2–3 lb bag of sand or 1 lb bag (or more) of
• Single-use cup that can have a hole poked in it
(e.g., plastic yogurt cup, foam cup)
• Cup, such as a glass, mug, or plastic cup
• Paper clip, skewer, or thumbtack (to poke a
hole in the single-use cup)
• 2 books, one approximately twice as thick as
the other
• Ruler (There is a ruler in the Equipment Kit if
you have already received it, or you can print
one at a website such as printable-ruler.net.)
• Tap water
• 2 Plastic bags (to cover the books or objects
you don’t want to get wet)
• Stopwatch (or cell phone with a timer)
• Camera (or cell phone capable of taking
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Wear your safety
goggles, gloves, and
lab apron for the duration of this investigation.
Read all the instructions for these laboratory
activities before beginning. Follow the instructions closely, and observe established laboratory
safety practices, including the use of appropriate
personal protective equipment (PPE).
Do not eat, drink, or chew gum while performing
these activities. Wash your hands with soap and
water before and after performing the activities.
Clean the work area with soap and water after
completing the investigation. Keep pets and children away from lab materials and equipment.
1. Read through the activities.
2. Obtain all materials.
3. Pour the sand or cornmeal in one, even layer
on the tray or cookie sheet.
4. Pour water slowly over the sand/cornmeal
until it is completely saturated. Pour off any
excess water outside.
5. With your hands, rub the sand/cornmeal so
it is flat, and let it dry overnight in the tray/
cookie sheet.
6. Using the paper clip, skewer, or thumbtack,
poke a hole in the side of the single-use cup,
1 cm up from the bottom of the cup.
Note: This investigation is best performed
outdoors or in an area in which it is easy to
clean up wet sand/cornmeal and water. Do
not dump any of the sand/cornmeal and
water mixture down the sink, because it can
cause clogging.
A Creating a Stream Table
In this activity, you will be measuring different
factors (see Step 5) for two different stream
models: one where the streambed is tilted at a
steeper angle and another where the streambed
is tilted at a shallower one. Propose four separate hypotheses for which of the two streambed
angles (steeper or shallower) will have the
highest values for sinuosity, velocity, relief, and
gradient. Briefly state why you feel that way.
Complete this information in the “Hypotheses”
section of the Lab Worksheet.
1. Bring the tray outside, and place the thicker
book in a plastic bag. Place the tray on one
end of the book so that it is tilted, as shown
in Figure 7.
2. Fill the cup without a hole in it with tap water
and slowly pour the water into the single-use
cup. Ensure that the single-use cup is right
above the higher end of the tray.
Note: Store extra tap water on-site if more
water is needed to form a stream.
3. Let the water trickle out of the hole in the
single-use cup down the sand/cornmeal.
Observe how the water forms a “stream”
in the table. Stop pouring after a small
streamflow has formed down the table.
4. On a separate sheet of paper, draw
what the formed stream looks like.
Label where erosion and deposition
occur along the streambed. Then take a
Figure 7. Tray Thicker
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Measure the slope of the stream; divide
the relief by the total distance (calculated
in Steps c and a). Note: If the stream is
curvy, this distance is the curvy distance;
if it is not, then this distance is the straight
6. Gently pour the excess water from the stream
table into the grass, and flatten the sand/
cornmeal out where the stream formed,
making a uniform layer.
7. Repeat Steps 1–6 with the thinner book to
obtain a more gradual stream formation.
8. While not required, if you feel particularly less
than confdent with your results from doing
only one trial run, feel free to do multiple trials
to test for validity.
A Scientifc Method: Modeling
Human Impacts on Stream
1. Design a procedure similar to Activity 1.
Choose one height to test the trials and
change a different variable to analyze the
same calculations for stream movement
and formation throughout the streambed.
photograph of your completed drawings of
the stream to upload to the “Photographs”
section of the Lab Worksheet.
5. Use the instructions below to calculate
the values for the different physical stream
features in the “Calculations” section of the
Lab Worksheet. Record these values in Data
Table 1 of the “Observations/Data Tables”
section of the Lab Worksheet.
a. Sinuosity = curvy distance (cm)/straight
distance (cm) (no units)
i. Use a ruler to measure the distance
from the mouth to the source of the
stream along the curve (curvy distance).
ii. Use a ruler to measure the distance
straight down the stream from the
mouth to the source of the stream
(no curve—straight distance).
iii. Now, divide the curvy distance by the
straight distance. Note: If there is no
curvy distance, then the sinuosity is 1.
b. Velocity = distance traveled (cm)/time to
travel (s) (recorded in cm/s)
Tear a small corner of a piece of paper
and crumple it. Time (in seconds) how
long it takes the paper to float downstream.
Divide the curvy distance by this time.
c. Relief = highest elevation (cm) – lowest
elevation (cm) (recorded in cm)
Measure the elevation change from the
beginning to the end of the stream. Use
the ruler to measure the highest point of
the incline to the ground for the highest
elevation and measure the bottom part
of the tray to the ground for the lowest
e. Gradient = relief (cm)/total distance (cm)
(rise/run) (recorded in cm) continued on next page
Note: In Activity 1, the heights of the source
of the streams were altered to observe how
streamflow and streambed formation were
affected. In Activity 2, use your streamflow
knowledge to design an experiment by
altering a different characteristic. You will
record the same calculations for your new
experimental setup.
ACTIVITY 2 continued
Choose a variable to change that models how
humans might modify a stream channel for
good or for ill. Activities such as pre-digging
a stream, adding a dam or other features
along the streambed, or adding plants along
these areas are all common factors that
can be altered within a streambed. Feel
free to implement additional materials from
your surroundings, such as using a rock to
represent a dam, for example.
2. Hypothesize whether each of the four
calculations (sinuosity, velocity, relief, and
gradient) will increase, decrease, or stay the
same, and include your reasoning in your
choices. Record this in the “Hypotheses”
section in your Lab Worksheet.
3. Test your new experimental design by
using the same procedure as in
Activity 1. On a separate sheet of paper,
draw what the formed stream looks like. Label
where erosion and deposition occur along the
streambed. Then take a photograph of your
completed drawings of the stream to upload
to the “Photographs” section of the Lab
4. Calculate the values of the four different
stream features in the “Calculations” section
of the Lab Worksheet. Record your fndings
in Data Table 2 of the “Observations/Data
Tables” section of the Lab Worksheet.
5. While not required, if you feel particularly less
than confdent with your results from doing
only one trial run, feel free to do multiple trials
to test for validity.
Submit the following two documents to
Waypoint for grading:
• Completed Lab Worksheet
• Completed report (using the Lab Report
Disposal and Cleanup
1. Dispose of the sand mixture either in the
environment or in the household trash.
Dispose of any other materials in the
household trash, or clean them for reuse.
2. Sanitize the work space, and wash your
hands thoroughly.
12 Carolina Distance Learning
Lab Worksheet
Activity 1.
Sinuosity hypothesis:
Velocity hypothesis:
Relief hypothesis:
Gradient hypothesis:
Activity 2.
Sinuosity hypothesis:
Velocity hypothesis:
Relief hypothesis:
Gradient hypothesis:
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Lab Worksheet continued
Observations/Data Tables
Data Table 1.
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Trial Sinuosity Velocity

Data Table 2.
Variable changed: _________________________________________________________________________
Book thickness used: ______________________________________________________________________

Trial Sinuosity Velocity

continued on next page
Activity 1.
curvy distance (cm)/straight distance (cm) =
sinuosity (no units)
___________ / ____________ =
Both the curvy and straight distances are
measurements taken from the stream formation
in the stream table. Please refer to Activity 1 for
more details.
distance traveled (cm)/time it takes to travel (s) =
velocity (cm/s)
___________ / ____________ =
The distance a small piece of paper travels
downstream divided by how long it takes to get
downstream is the velocity. Refer to Activity 1 for
more details.
highest elevation (cm) – lowest elevation (cm) =
relief (cm)
___________ – ____________ =
Subtract the lowest elevation of the stream from
the highest elevation of the stream to calculate
the relief. Please refer to Activity 1 for more
relief (cm)/total distance (cm) = gradient (cm)
___________ / ____________ =
Divide the relief by the total distance of the
stream to calculate the gradient. Please refer to
Activity 1 for more details.
Activity 2.
curvy distance (cm)/straight distance (cm) =
sinuosity (no units)
___________ / ____________ =
Both the curvy and straight distances are
measurements taken from the stream formation
in the stream table. Please refer to Activity 1 for
more details.
distance traveled (cm)/time it takes to travel (s) =
velocity (cm/s)
___________ / ____________ =
The distance a small piece of paper travels
downstream divided by how long it takes to get
downstream is the velocity. Refer to Activity 1 for
more details.
highest elevation (cm) – lowest elevation (cm) =
relief (cm)
___________ – ____________ =
Subtract the lowest elevation of the stream from
the highest elevation of the stream to calculate
the relief. Please refer to Activity 1 for more
relief (cm)/total distance (cm) = gradient (cm)
___________ / ____________ =
Divide the relief by the total distance of the
stream to calculate the gradient. Please refer to
Activity 1 for more details.
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continued on next page
Lab Worksheet continued
Activity 1.
Activity 2.
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Lab Questions
Please answer the following entirely in your own words and in complete sentences:
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1. Background—What is important to know
about the topic of this lab? Use at least one
outside source (other than course materials)
to answer this question. Cite the source
using APA format. Answers should be 5–7
sentences in length.
2. Outcomes—What was the main purpose of
this lab?
3. Hypotheses—What were your hypotheses for
Activity 1? What were your hypotheses for
Activity 2? Identify each hypothesis clearly,
and explain your reasoning.
Materials and Methods
4. Using your own words, briefly describe
what materials and methods you used in
each of the activities. Your answer should be
sufciently detailed so that someone reading
it would be able to replicate what you did.
Explain any measurements you made.
5. Based upon the results of each activity,
explain whether you accepted or rejected
your hypotheses and why.
6. What important information have you learned
from this lab? Use at least one outside
source (scholarly for full credit) to answer this
question. Cite the source using APA format.
Answers should be 5–7 sentences in
7. What challenges did you encounter when
doing this lab? Name at least one.
8. Based upon your results in Activity 2, what
next step(s) might a scientist take to explore
how humans affect stream ecosystems?
Literature Cited
9. List the references you used to answer these
questions. (Use APA format, and alphabetize
by the last name.)
Now copy and paste your answers into the Lab Report Template provided. Include the data
tables and photographs. You may wish to make minor edits to enhance the flow of your
resulting lab report.
18 Carolina Distance Learning
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Stream Morphology
Investigation Manual
Carolina Biological Supply Company
www.carolina.com • 800.334.5551
©2018 Carolina Biological Supply Company
CB781631806 ASH_V2.1

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