Name: _________________________________________ Class: ________ Date: ___________
Sedimentation Lab
In this lab, you will explore how grain size and energy within the system affects
settling rates of particular sediments. This simulates how grains of different
sizes naturally settle out of solution at certain currents in a lake or river
system. Students will also learn how to construct a stratigraphic column
showing the graded bedding.
Materials:
Pea Gravel, coarse grained sand, fine grained sand, top soil, water, glass jar,
paper, colored pencils
Procedure:
1. Obtain a glass container and make sure it is clean.
2. Scoop enough of each material to make about a 1 inch layer of each.
3. Add enough water to fill the container mostly to the top.
4. Shake the jar vigorously for 2 to 3 minutes.
5. Carefully observe the various sediments as they settle out of the water.
Record your observations in the table provided.
6. After recording your observations, let the jar sit to further settle, answer
the questions, and draw your stratigraphic column.
Order
1
2
3
4
5
Sediment Type and Observations
Name: _________________________________________ Class: ________ Date: ___________
Conclusions: Please answer the following questions using complete
sentences.
1. What does the shaking of the bottle represent in a water system? Is this
constant for all water systems or can it vary? What might cause the
variations?
2. Explain the relationship between grain size and the rate of settling. Why
do you think the grains settled in the order in which they did?
3. Could all varieties of sedimentary rocks form under all conditions based
on our settling rate?
4. Mudstones are fairly fine grained sedimentary rocks. Under what
conditions would such a rock form? Give an example of a location where
a mudstone may form.
5. How could you determine how much energy or motion there was in a
stream if all you have to see was a graded bed (your “sediment column”)?
Name: _________________________________________ Class: ________ Date: ___________
How to make a stratigraphic column
To the right is a very simplified
diagram of a stratigraphic
column. The most important
things to notice here are the
changes in rock type, the
thickness of the rock units and the
order in which these rock layers
are grouped. A more complete
stratigraphic column would give
us other important observations,
such as color of the rocks and the
fossils contained within them.
This is a simplified diagram of
the geology of Signal Hill, Long
Beach, California - one of the
most important oil fields in North
America in the twentieth century.
1)Look at the rocks
This may seem obvious, but it is important before you begin to get a general sense of the
rocks in front of you. It will make it easier to make a description of the rocks later if you get
a good overview first.
2)Look for changes in rock type
If the rocks in one part of the outcrop appear very different, then it is possible that they
should be their own "unit". Dividing the rock outcrop into units is based on changes either in
fossils, color, rock type, and other factors, or all of these factors combined.
3)Measure the section
Once you have determined different units, you may then measure the thicknesses of these
units. (Geologists are generally not particularly interested in the length of the rocks, only the
widths.)
4)Start describing!
Now it's time to make specific observations about the rock you are looking at. What fossils
do you see? What is the color? What type of rock could form?
Name: _________________________________________ Class: ________ Date: ___________
Sedimentation Lab
Please draw your stratigraphic column on this page. Make sure to be very
specific with the thicknesses of your sediment layers, their colors, and any
other observations you may have. Neatness and accuracy counts. Take your
time and draw it correctly. See reverse side for more instructions and an
example. Make sure to label each part correctly and thoroughly.