SKHS Earth Systems Lab: Ocean stratification, The Myth of Davy Jones’s Locker
The Myth of Davy Jones’s Locker: For centuries, sailors believed that
bodies buried or lost at sea did not sink to the bottom. They believed
that a special depth existed between the surface and the bottom of the
ocean where a body would remain suspended. Sailors called this region
of the sea “Davy Jones’s Locker.” Although this myth isn’t true this lab
involves creating a model stratified layers which do exist in the sea.
Purpose: What physical properties of ocean water can cause it to be stratified into three separate
layers? In this lab you will develop a model showing stratified layers of water and place vials into the
water to prove the density of the layers is different.
Background Information:
Paragraph one: Describe the appearance of the demonstration column.
Paragraph two: Define density and describe how substances of various densities interact when they are
together, in other words floating and sinking.
Paragraph three: Explain how varying temperature of a substance affects density. Explain how varying
salinity of water affects density.
Hypothesis: Write a hypothesis that you believe explains the phenomenon observed in the
demonstration column. How can you design and build a model of ocean water stratified into 3 layers?
How can you use floating vials to provide evidence that the density of the three layers is different?
Procedures: Write numbered steps of how the cylinder should be set up and how the vials should be
constructed.
Materials:
 45 cm tall plastic cylinder
 Fresh water
 Funnel
 Salt water
 Rubber tubing
 3 beakers (500 ml)
 4 Watertight vials
 Digital balance
 Marking pen or wax pencil
 Graduated cylinder
 BB’s
 thermometers
 Ice bath
 Hot water bath
Data and observations: Measure the temperature of each liquid. Measure the relative salinity of each
liquid using a hydrometer.
Diagram: Include a 1 page diagram of the column you have made. Label the temperature and
relative density of each water layer. Include the vials with BB’s in them and label their density. Give
the diagram a title.
Data table for vials: Record the mass and volume of each vial. Calculate the density of each vial.
Conclusion: see requirements in “submit: formal lab report”
SKHS Earth Systems Lab: Ocean stratification, The Myth of Davy Jones’s Locker
SUBMIT: FORMAL LAB REPORT
Introduction –
 Purpose of experiment. (Paragraph 1)
 Background information: (3 paragraphs)
 Hypothesis –(1 paragraph)
MaterialsBulleted list of materials
Procedures –



Use class procedures
Write the procedures step by step and number each step.
Ask yourself: Can someone else follow your procedures and conduct the exact same
experiment?
Data/ observations–
 Include a 1 page diagram of the column you have made. Label the temperature and relative
density of each layer. Be sure the difference between each vial is obvious. Give the diagram a
title.
 Data tables:
1. Table one: Solution in Beaker’s A, B, and C’s relative density using a hydrometer &
temperature
2. Table two: Vial A, B, C, and D’s mass, volume, and calculated density.
Analysis and conclusions o Restate the problem and hypotheses: (Paragraph 1)
o Discuss your results: (Paragraph 2) Include at a minimum:
o Describe the properties of each water layer of your column. Be specific including the
temperature and relative density according to your hydrometer.
o Describe where each vial was positioned and both the number of BB’s they contained
and their measured density.
o Discuss how this model applies to an actual ocean system. How is the ocean different from the
model you created? (Paragraph 3)
o Describe what heats the surface layers of the ocean.
o Are their layers of fresh water anywhere in the ocean? What is the source of freshwater
in the ocean layer? Which layer is does this related to in your model?
o How does the Mediterranean Sea’s temperature and salt content compare to the
Atlantic Ocean. Which layer would the Mediterranean be in your model?
o Your model did not involve mixing which makes it unlike the ocean. Differences in
density creates ocean currents. Define “thermohaline current” and describe how
different temperature water would create current and also different salinities would
create current.
SKHS Earth Systems Lab: Ocean stratification, The Myth of Davy Jones’s Locker
Procedures:
1. Three solutions have been prepared

Beaker 1 Ice Cold Ocean Water

Beaker 2 Cold Fresh Water

Beaker 3 Warm Fresh Water
2. Construct a data table to record the relative density and temperature of the solutions in Beakers
1, 2, and 3.

Place a hydrometer into each beaker and record the relative density of the water. The
unit for this will be the number from the hydrometer and the words “relative density”.

Measure the temperature with a thermometer of each beaker and record.
3. Add varying numbers of BBs to four vials: Note: be careful to cap the vials tightly so no water
can get inside.
 Vial “A”: Make a vial that sinks in beaker 1 (cold ocean water)
 record number of BB’s used = ______
 Vial “B”: Make a vial that sinks in Beaker 2 (cold fresh water) BUT floats in Beaker 1
 record number of BB’s used = ______
 Vial “C”: Make a vial that sinks in Beaker 3 (warm tap water) BUT floats in beaker 2
 record number of BB’s used = ______
 Vial “D”: Make a vial that floats in Beaker 3
 record number of BB’s used = ______
4. Carefully slide the vials into the bottom of the cylinder.
5. Carefully pour the water from Beakers 1, 2, and 3 into your plastic cylinder. To minimize mixing of
the layers, use rubber tubing and a funnel to carefully add the water and avoid mixing.
6. Draw a diagram of your column and label temperature and relative density of each layer. Be sure
the difference between each vial is obvious. Give the diagram a title.
7. Construct a data table to record the mass, volume, and calculated density, and number of BB’s of
Vials A, B, C, and D. Once vials are properly constructed place one into a graduated cylinder and use
water displacement to record the volume of the vials. Then place each one on a digital balance and
record their mass. Calculate the density of Vials A, B, C, and D.
SKHS Earth Systems Lab: Ocean stratification, The Myth of Davy Jones’s Locker
Hypothesis Period B: If salt is added to cold water then the water will be more dense and it will
be at the bottom of the water column. If fresh water is heated then it will be the least dense
and be at the top of the water column. If water with a medium amount of salt and temperature
is made then it will be in the middle of the water column. If a vial has few BB’s then it has low
density and will float. If a vial has many BB’s then it has high density and will sink. If a vial is
suspended in the middle then it has more BB’s then the floating vial and less BB’s then the
sinking vial.
Hypothesis Period C: If we change the temperature and amount of salt in the water then we
can create 3 stratified layers. The bottom layer will be cold with a lot of salt with the highest
density . The middle layer will be warmer and less salt and medium density. The top layer will
be the warmest with the least amount of salt with the lowest density. If we place different
amounts of BB’s in each vial then the vial at the bottom, will have the most, the vials in the
middle will have less and floating vials at the top will have the least.
Hypothesis Period D: If the salt content and temperature of water is varied then 3 stratified
layers can be made in a column of water. If fresh hot water is added then it will be at the top. If
a small amount of salt is in warm water then it will be in the middle. If a large amount of salt is
added to cold water then it will be at the bottom. If bb’s are placed in plastic vials then the vial
with the greatest amount will be most dense and sink. The vial with the least bb’s and lowest
density will float at the top. The vial with the medium amount of BB’s will have a moderate
density and float in the middle.