Sensational Sediments
Focus Question
Are all sediments the same?
Activity Synopsis
Using sediment samples from varying parts of the seafloor, the schoolyard, and a local
beach, students will compare a variety of sediment samples and sort the samples by a
single attribute.
Time Frame
1 hour
Student Key Terms
 soil
 sample
 sediment
 biogenic
 lithogenic
 abiogenic
Objectives
The learner will be able to:
 Sort sediment samples based on a single attribute.
 Compare a variety of sediment samples.
 Describe sediments using the senses.
 Communicate using sensory descriptors.
Kindergarten Standards Addressed
Social Studies Standards
K.5.1, K.5.2
Science Standards
IA1a, IA2a, IA4a, IB1a, IB1b, IIA3c, IIIA2a, IIIA2b, IIIA1a, IVA1a
Math Standards
Data IB1, Algebra IA1, IA2
Language Arts Standards
K-R3.1, K-RS3.2
Background
From COASTeam Aquatic Workshops: Oceans (Grade K); a joint effort between the COASTeam Program
at the College of Charleston and the South Carolina Aquarium – funded by the SC Sea Grant Consortium
1
Key Points
Key Points will give you the main information you should know to teach the activity.

All sediment samples do not look the same. Physical characteristics, such as
grain size and color, vary according to the origin of the sample. Clay is the
smallest grain size and includes any sediment less than 1/256 mm in diameter.
The next largest grain size is silt, with diameters ranging from 1/256 mm-1/16
mm. Sand grains range from 1/16 mm-2 mm in diameter; and, finally, gravel
encompasses all sediments larger than 2 mm in diameter. Sediments may be
classified as lithogenic (erosion of rocks), biogenic (hard parts of organisms),
volcanogenic (ejected from volcanoes), authigenic (precipitated from
reactions in the water), or cosmogenic (originate from outer space).
Detailed Information
Detailed Information gives more in-depth background to increase your own knowledge,
in case you want to expand upon the activity or you are asked detailed questions by
students.
Sediment is the collective name for loose, solid particles that originate from both
weathering and erosion of preexisting rocks; or chemical precipitation from solution,
including secretion by organisms in water (McGeary, 1996). Weathering, erosion, and
transportation are processes that greatly affect the character of sediments (McGreary,
1996). Weathering breaks down rocks that are either moving or stationary, while erosion
is the physical removal or rock particles by agents such as rivers or glaciers (McGreary,
1996). After a rock particle is eroded, or picked up, it is transported. Transportation is
the movement of eroded particles by agents such as rivers, waves, glaciers, or wind
(McGreary, 1996). During transportation, a rock particle may be rounded and sorted.
Rounding is the grinding away of sharp edges of rock fragments and it occurs when
particles hit and scrape against one another. (McGreary, 1996). Boulders in a stream
may show substantial rounding in less than one mile of travel (McGreary, 1996)! Sorting
is the process by which sediment grains are separated according to grain size (McGreary,
1996). Boulders weigh more than sand, so a river must flow more rapidly to transport a
boulder (McGreary, 1996). When a river hits an area of flat land, the water slows down
and loses energy and the heaviest particles are deposited. Deposition occurs when the
transported rocks come to rest. Deposition may also occur when chemical or organic
sediments “settle out”; for example collection of mollusk shells on the seafloor, or plant
material on the floor of a swamp (McGreary, 1996). The conditions in the environment of
deposition also affect the appearance of sediment.
In South Carolina, the sand on our beaches is primarily composed of pieces of quartz and
feldspar that have been eroded from the mountains and weathered by the rivers as they
travel across the state. The appearance of beach sand varies depending on the location of
the beach. Sand on a tropical beach may be made of carbonate grains from offshore
corals, algae, and shells. Some Hawaiian beaches are made of weathered fragments of
From COASTeam Aquatic Workshops: Oceans (Grade K); a joint effort between the COASTeam Program
at the College of Charleston and the South Carolina Aquarium – funded by the SC Sea Grant Consortium
2
basalt. A beach with high-energy waves will most likely be composed of gravel, as the
smaller sand particles are swept away. (McGreary, 1996)
While digging in your garden, you may have noticed that all of the sediment in your
shovel doesn’t look the same. The yard may, for example, contain a mix of sand and red
clay. The soil in your back yard may contain sediments from the erosion of large rocks,
and it may also contain the decomposing remains of plants and animals. When we look
at sediments from the ocean floor, we notice the same phenomenon.
(The following information is from “Is It Mud or Isn’t It?” by Rachel McEvers, written
for NOAA Ocean Exploration http://oceanexplorer.noaa.gov)
Sediment can be classified either by grain size or on basis of mode of formation. In the
first case, the classification depends on grain size. In the second case one must interpret
the origin of the deposit. From smallest to largest particle size are clay, silt, sand and
gravel. As for origin, sediments can be classified as lithogenic (coming from land by
erosion of rocks), biogenic (derived from hard parts of organisms, usually calcium
carbonate and silica), authigenic (precipitated by chemical or biochemical reactions in the
water), volcanogenic (particles ejected from volcanoes) and cosmogenic (grains that
originate in outer space) (Pinet, 1998).
Composition of sediments depends on several factors. Under high energy
conditions (strong currents) fine grains stay in suspension and more fine grains, which
may have temporarily settled, are resuspended. Coarse grains are able to settle out in
these conditions. Low energy sites don’t contain as many coarse grains because there is
not enough energy to transport them to these areas. The shape of the grains also tells us
something. Generally, the more rounded the grains, the older the sediment. This means
they have been tumbled and rolled around for a long time. Younger grains may also be
rounded if they’ve been in a high-energy area for a period of time.
Proximity to land also helps determine the composition of seafloor sediment. The
continental shelf is relatively shallow and close to land and thus receives much more
lithogenic sediment from rivers and wind-blown dust. The deep sea receives some of the
lithogenic sediment carried by strong currents but the majority of the sediment here is the
hard parts of surface-water organisms that settle to the bottom (Pinet, 1998).
The sediment used for this activity came from the Savannah Scarp and the
Charleston Bump. The Savannah Scarp consists of a series of rocky ridges and outcrops,
where Gulf Stream currents have diverted sediments away from the underlying rock. This
shelf-edge reef here occurs at about 55 m (180 ft), and the bottom drops steeply to 70 m
(250 ft) or more. Along this edge is a spectacular reef habitat, consisting of large rocks,
ridges, ledges, caves and overhangs that provide habitat for an abundant and diverse
fauna. Off the coast of Savannah, Georgia, however, the shelf-edge reef is very well
developed into a series of two or more parallel ridges in depths from 55 m (180 ft) to 90
m (295 ft) (Sedberry, 2001). The site includes a variety of habitats between depths of 150
to nearly 300 ft, and rocky ridges that extend more than 20 ft above the bottom.
The Savannah Scarp sediment sample was taken about 60 miles offshore at a depth of
approximately 200 ft. Henry and Barans' 1984 studies of the Savannah Scarp showed
From COASTeam Aquatic Workshops: Oceans (Grade K); a joint effort between the COASTeam Program
at the College of Charleston and the South Carolina Aquarium – funded by the SC Sea Grant Consortium
3
that the limestone rock in this area probably originated as loose grains of calcium
carbonate sediment (oolitic sands, to be more precise) that were cemented together when
the sea level was much lower, approximately 18,000 yrs ago (Sautter, 2001).
The Charleston Bump is a deepwater seafloor feature 80 to 100 miles southeast of
Charleston, South Carolina. The Bump rises from the relatively flat Blake Plateau that
lies beyond the edge of the continental shelf in the South Atlantic Bight. From depths of
over 700 m (2300 ft), the bottom ramps up to a shallow scarp at 375 m (1230 ft). From
there, the bottom plunges 125 m (410 ft) in a series of steep scarps with rocky cliffs,
overhangs and caves. The Charleston Bump also deflects the flow of the Gulf Stream. As
the warm water of the Stream flows northward out of the Florida Straits, it encounters the
Bump and is deflected offshore, causing eddies and other current features that are
important fish habitats. This mixing and upwelling brings nutrient rich, deep water to the
surface, enhancing plankton production and producing food for fishes (Sedberry, 2001).
The Charleston Bump sediment was taken about 100 mi. offshore at a depth of about
1600 ft.
The sediment samples from the Charleston Bump and the Savannah Scarp will
differ in appearance. The Bump sediment is primarily biogenic and the Scarp sediment is
primarily lithogenic. The Scarp is much closer to land than the bump (60mi offshore vs.
100mi.) and therefore receives more eroded rock from rivers and wind-blown debris.
The Scarp is much more shallow than the Bump. The Gulf Stream runs past the Bump
making it a very high-energy area thus preventing fine particles from settling out. The
color of the two sediments is different. The Scarp sediment is a very dark almost
greenish color whereas the Bump sediment is a light to medium brown. Students may
also notice a couple of similarities between the two sediments. They should be able to
find many of the same organisms or “grains” in each of the two samples. Grain shape in
both is mixed. There are rounded coral and rock pieces and angular shell fragments in
both.
References:
McGreary, David and Plummer, Charles C., 1996
“Physical Geology.” Wm. C. Brown Publishers. Dubuque, IA.
Pinet, Paul R., 1998.
“Invitation to Oceanography” Jones and Bartlett Publishers, Inc. London, England
“A Profile of Savannah Scarp” from NOAA Ocean Exploration website (2001)
George R. Sedberry, Senior Marine Scientist, Marine Resources Research Institute,
South Carolina Department of Natural Resources
“A Profile of the Charleston Bump” from NOAA Ocean Exploration website (2001)
George R. Sedberry, Senior Marine Scientist, Marine Resources Research Institute,
South Carolina Department of Natural Resources
From COASTeam Aquatic Workshops: Oceans (Grade K); a joint effort between the COASTeam Program
at the College of Charleston and the South Carolina Aquarium – funded by the SC Sea Grant Consortium
4
“Getting to the Bottom of a Rocky Rubble Reef” from NOAA Ocean Exploration
website (2001) Dr. Leslie R. Sautter, Dept. of Geology and Environmental Sciences,
College of Charleston, Charleston, SC
Procedures
Materials
 Sediment samples - You may request FREE samples of Charleston Bump and
Savannah Scarp sediment at
http://oceanica.cofc.edu/samplematerial/samples.htm; also bring in a sample
from a local beach and from the schoolyard.
 Dissecting scopes or magnifying glasses
 Coffee filters or plastic petri dishes
Procedure
1. Divide students into small groups (the number per group will depend on the
number of scopes and magnifying glasses available).
2. Ask students “What is soil?” “Where do we find soil?” “Can we find soil
under the water?” “Do all soils look the same?”
3. Tell the students “Today we will look closely at different soil samples and
decide if all soils are the same. We will be looking at some soils that are from
the bottom of the ocean!”
4. Place a sample of the sediments in plastic petri dishes, or on coffee filters.
Label the petri dishes with “B” for Bump, “S” for Scarp, “Y” for yard, and the
first letter of the beach from which you collected the fourth sample. Allow
the students time to investigate the samples with the scopes and magnifying
glasses.
5. Lead a class discussion about the characteristics of the sediments. Are they
smooth, rough? What color are the samples? How do they smell? How do they
look? If you GENTLY swirl the samples in the plastic petri dish, do they
make the same sound?
6. Prompt the students to separate the samples according to these attributes:
 Samples that have a dark color and samples that have a light color.
 Samples that have pieces of shell and samples that do not have pieces
of shell.
 Samples that have bigger “pieces” (grains) and samples that have very
small “pieces” (grains).
7. Lead a discussion about the sediments. “Why do the samples from the bottom
of the ocean have shells, but the sample from our school yard does not?”
“Why do you think that the soil in our schoolyard is made of very, very tiny
pieces and the sediments from the ocean floor are made of larger pieces?”
Assessment
From COASTeam Aquatic Workshops: Oceans (Grade K); a joint effort between the COASTeam Program
at the College of Charleston and the South Carolina Aquarium – funded by the SC Sea Grant Consortium
5
The students will sort sediments based on color and size. Have 3-5 extra-small bags of
soil, for example, gardening topsoil and clay; 3-5 extra-small bags of sand (use colored
chalk to vary the color); and 3-5 extra-small bags of pebbles of varying colors.
Tell the students to observe the color and size of their individual sample. Then, have the
students look around the classroom at the other students’ samples. Prompt the students to
sort themselves by color (for example, white pebbles and white sand would be a group,
brown pebbles and colored brown sand would be in a group). Instruct each group to
present its color.
Then, prompt the students to sort themselves according to size. Remind the students that
they are looking at the size of an individual piece of “dirt”, sand or rock – NOT the size
of the entire sample! At this point, all of the sand students should be together, all of the
pebble students should be in a group, and all of the soil student should be in a group.
Mastery/Nonmastery: The student can classify himself by size and color.
Members of the COASTeam Aquatic Workshops development team include: Katrina
Bryan, Jennifer Jolly Clair, Stacia Fletcher, Kevin Kurtz, Carmelina Livingston, and
Stephen Schabel
From COASTeam Aquatic Workshops: Oceans (Grade K); a joint effort between the COASTeam Program
at the College of Charleston and the South Carolina Aquarium – funded by the SC Sea Grant Consortium
6