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Title:
Crinoids:
Flowers of the Iowa Seas
Grade
Level: 3-12
Time
Needed:
2
Class Periods
Goals\Objectives\Student
Outcomes:
The
student will gain awareness of.....
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The
continuous natural changes that have shaped Iowa's geologic
landscape
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The
beauty and diversity of a group of extinct Iowa marine
animals called crinoids.
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The
importance contributions of professional and amateur
scientists who studied Iowa rocks and fossils
The
student will be able to....
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recognize fossils and understand how they provide evidence
of earlier lives and environments
-
learn about early scientific surveys of the mineral wealth
of the state
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analyze fossil evidence and compare extinct animals to
modern ocean life.
-
summarize the geologic history of Iowa and understand why
some if it is missing.
-
explain how amateur collectors could help or harm the study
of Iowa's ancient life.
Background
When
a child places a hand in wet cement an impression formed that
may remain for generations. In the future others who may see the
impression might learn something about the child and the
activities of that day. Rocks and fossils are much like the
cement and hand print of the child. They provide evidence of
past life and environments. Interpreting the specimens allows a
geological and zoological history of an era to be written.
This
lesson plan is about Iowa's environment and how scientists
observed, organized, and evaluated rock layers and fossils to
develop an understanding of the past. In particular, this lesson
focuses on a group of extinct Iowa marine invertebrates called
crinoids. Iowa's crinoid fossils are notable because many of
them have been preserved intact, which helps scientists learn a
great deal about crinoids as well as Iowa's ancient seas.
We
usually think of time in hours and years, generations and
civilizations. Geologic time, however, covers millions of years,
and must be measured by physical evidence. One important way to
measure geologic time is by studying the remains of creatures
that died over various eras and left behind their impressions in
stone as fossils.
The
geologic time table is divided into four major eras - Precambrian
(which means origin of life), Paleozoic (ancient life), Mesozoic
(intermediate life), and Cenozoic (recent life). Those
eras are further divided into periods with characteristic
fossils and rock formations.
Fossils
are the remains or traces of organisms of a past geologic age
buried in the earth's crust. A fossil can be a print of a leaf,
the path of a worm, the shell of a marine animal, the footprint
of a dinosaur, or the skeleton of a man. Remains may have been
fossilized by undergoing freezing, drying, burial in tar or
bogs, or by becoming carbonized or petrified. Other remains were
covered in sediment that hardened. When the remains decayed,
they left a cavity known as a natural mold. It this cavity is
filled, duplicating the shape and surface of the fossil, it is
called a cast.
To
create economic growth for Iowa in the 19th century, it was
necessary to investigate the state's soils and mineral resources
for the riches they might yield. Three professional geologists
were hired to produce detailed survey maps. The first was David
D. Owen, employed by the U.S. government to prepare geologic
reports when Iowa became a state. Later, James Hall and Charles
White conducted surveys for the state government. Their
detailed observations resulted in interpretations very close to
our modern geologic maps prepared with modern techniques. Rocks
and minerals are important resources.
Three
Iowans won international recognition for their life-long study
of local crinoid fossils. Their responsibility collecting and
research enabled scientists around the world to learn of the
remarkable fossils in the cliffs around Burlington and the
quarries near Le Grand and Gilmore City.
Charles
Wachsmuth
came to Iowa from Germany in 1855. He often wandered the cliffs
near his Burlington home, where he discovered crinoid deposits.
Fascinated, he began to collect and study specimens and he
published his findings. Later, he was offered a position at
Harvard University as an expert on crinoids. His wife, Bernadine
Lorenz Wachsmuth, worked with him in collecting,
researching, and writing about their discoveries.
Frank
Springer
became interested in paleontology as a law student at the
University of Iowa. He established a law office in Burlington
and began an association with the Wachsmuths, sharing their
interests and collaborating on many publications. Even after he
moved to New Mexico, Springer often returned to Burlington to
continue his crinoid research.
Burnice
H. Beane
helped manage the family farm in Le Grand where as a boy he
explored the legrand quarry and watched scientists excavate
specimens. Two of these visitors were Frank Springer and Charles
Wachsmuth. As an adult, Beane continued exploring the quarry,
where workmen helped him collect thousands of specimens. His
painstaking skill in preserving the crinoids resulted in an
important scientific legacy. Many paleontologists and amateur
collectors sought his advice and an opportunity to tour the
famous quarry with the man who had become the guardian of its
treasurers.
Crinoids
were animals attached to the sea floor by flexible, rooted
stalks. When they died, they usually broke loose and drifted
away. The crinoid fossils found in the legrand quarry are
remarkable because many of them were preserved nearly intact.
The reason this happened is that nests of crinoids were rapidly
buried in shallow depression that protected their bodies from
currents. Lime-rich mud preserved their remains and hardened
them into stone. The limestone slabs found near legrand contain
fossilized crinoids and other sea animals in such abundance and
detail that they have fascinated scientists around the world.
360
million years ago (in the Paleozoic era or Mississippian period)
North America was located near the equator. Much of the land -
including what's now Iowa - was submerged under shallow tropical
seas. These warm waters teemed with countless creatures.
The
inland seas reportedly swelled and retreated, alternately
building up and exposing layers of sediments, sandwiching the
remains of crinoids and other living things, and casting their
impressions in stone.
Crinoids,
commonly called "sea lilies" or "feather
stars," belong to the echinoderm family (bodies covered
with plates of calcite that form a skeletal structure) along
with starfish, sand dollars, sea urchins, and sea cucumbers.
Some
crinoid species crawled, some swam, and others attached
themselves to rocks on the sea floor. They fed by means of
cilia, located along grooves in their arms and branches, that
brought tiny marine life to the mouth. Today, crinoids live in
all the world's oceans, and where they're found, their abundant
numbers and vibrant colors give the appearance of an underwater
flower garden.
Animals
get food directly from plants or other animals that eat plants.
Crinoids are animals because they eat other marine life. Plants,
on the other hand, make food by drawing energy from the sun and
salts from water.
Crinoids
have cup-shaped bodies with at least five feathery arms atop
column sections that form cylinders and spirals. These shapes
seem to radiate from a central point. This is called radial
symmetry.
Fossils
offer rare glimpses into our past. But many of these fragile
artifacts face destruction each year from mining, construction,
and erosion. In addition, private companies, individuals,
museums, and universities all seek to unearth specimens to add
to their collections. Laws protect many state and federal lands
from the indiscriminate collecting of fossils. (Private lands
are not covered by current or proposed laws.) The state of Iowa
prohibits anyone from collecting fossils, stones, plants, and
archeological material in parks, preserves, waterways, and lands
owned by the state. There is a proposed federal law to limit
collecting on federal lands to protect fossil resources.
Responsible
professional and amateur collectors care for their specimens and
record information about each one. Many collectors work with
specialists from the Geological Survey, from universities and
colleges, and form geological organizations to uncover more
clues to our past. This cooperation and exchange of information
contributes to our knowledge of Iowa.
Vocabulary:
Carbonized:
all plants and animals, and some nonliving things, contain the
element carbon, which sometimes remains after incomplete decay
as hard black deposit.
Cast:
when
dead objects decay, they sometimes leave a cavity known as a
natural mold. When this is filled by sand or clay or plaster,
the cast duplicates the shape and surface of the fossil.
Concretion:
hardened
lumps of minerals deposited around seeds, shells, or rocks.
Coprolite:
fossilized
excrement that provides information about ancient creatures and
their habits.
Crinoid:
("lily-like"): a group of marine animals also called
sea lilies, belonging to the same family as starfish, sand
dollars, sea urchins, and sea cucumbers. Certain crinoid species
once thrived in Iowa's ancient seas.
Daemonelix
("devil's
corkscrew"): a spiral-shaped fossil.
Echinoderm
("spiny-skinned"): marine animals with plates or
spines that provide skeletal support. This group includes the
crinoid and its relatives.
Erosion:
the
slow wearing away of the earth's surface, especially by wind,
water, or glacial ice.
Fossil:
the
remains, impression, or trace of an animal or plant from a past
geological age that has been preserved in the earth's crust.
Gastroliths:
fossilized
stones from the stomachs of animals, apparently swallowed to
help grind and digest food.
Geology:
the
scientific study of the earth's surface and its physical
features, especially rocks.
Index
fossil:
a fossil usually formed during a narrow period of time that is
used to identify geologic formations on the surface and below
the earth.
Invertebrate:
animals
without a spinal column
Matrix:
the
natural material in which a fossil, metal, gem, crystal, or
pebble is embedded.
Mold:
the
impression or cavity left when a dead object decays or
dissolves.
Paleontologist:
a
scientist who studies fossils and other ancient life forms form
the geological past.
Petrified:
a
scientist who studies fossils and other ancient life forms from
the geological past.
Pseudo-fossils:
stones
shaped by nature that resemble fossils.
Zoology:
the
science that studies animals and animal life.
Materials:
Collections
of rocks, feathers, leaves, shells, etc.
Iowa's
state rock-the geode
Procedures:
1.
Discuss what is "old." How can you tell something
old from something new?
2.
Talk about change. People change as they grow older. The
environment changes too.
3.
Discuss changes in nature caused by
flood, earthquakes, or erosion. How do human activities such
as farming, mining, or building change the environment?
Imagine all the different ways the landscape of Iowa has
changed over millions of years.
4.
Have students share their natural history collections, such
as feathers, leaves, seeds, shells, rocks, or fossils.
Display them in egg cartons or shoe boxes. Plastic
magnifiers are useful for observing small objects. Make
rubbings of different kinds of bark and leaves.
5.
Have students - alone or in groups - gather objects, sort
them, then label them. Make a nature notebook that includes
notes and drawings.
6.
Have students write a report on Iowa's official state rock,
the geode. Why was it made the state rock? How are geodes
formed and where are they found in Iowa? Bring a geode to
class and crack it open with a small hammer. What does it
look like inside?
Make
Your Own Fossils:
1.
Flatten out clay and make an impression with your hand or
press in flowers, leaves, or shells. Remove them carefully
and let them dry.
2.
Fill a container with soil mixed with some clay. Add water
and stir until the mixture is thick and can be molded. Stir
in small items - shells, pebbles, twigs, feathers, or
leaves. Shape a mudpie that completely seals in some of
these small items. Allow mudpies to dry completely. Before
you break them open, have students discuss how they think
the "fossils" will turn out. Break them open and
then label them. Make rubbings or plaster casts of them.
3.
Cover an object like a shell, a leaf or a chicken bone with
petroleum jelly. Mix together 1/2 cup plaster of Paris and
l/4 cup water. Let the mixture set. Pour the plaster mix
into an empty container - a pie plate or the bottom of a
plastic milk jug. Press your greased object into the
plaster. Dry for 24 hours. Remove the object. Cover the
plaster with petroleum jelly and press clay over the mold.
Then carefully remove the clay from the mold.
4.
Put sand in different cups and stir in a few drops of
different colors of tempera paint or food coloring. Let dry.
Pour the colored sand into a large glass jar, alternating
layers of different colors. Add small shells or pebbles
along with the layers. Use a knife or stick to create
valleys and mounds in the layers. Discuss how this model
relates to Iowa's landscape.
Extensions:
1.
Plan a trip across Iowa to see all the different geologic
deposits. As a guide, use the geologic map of Iowa in Landforms
of Iowa by Jean C. Prior or Iowa's Natural Heritage
edited by Tom Cooper. With the help of these books, examine
the locations of different deposits. Make a map showing your
travels.
2.
Make a display showing the different geological periods in
Iowa history and what happened during the periods.
Can you imagine what a million years is like? Can you
imagine a million of anything? How would you depict the vast
amounts of time involved in the history of life on earth?
3.
Have students bring in rocks to examine and identify.
Include among the "mystery minerals" quartz,
hematite, talc, mica, calcite, graphite, and limestone. Use
a rock and mineral field guide book as a reference. Number
the samples, then analyze them for color, streaks, hardness,
shine and weight. Spoon vinegar over them and see what
happens (vinegar fizzes when it comes in contact with
limestone and calcite.) After identifying the mineral
samples, ask students what products the minerals can make.
Examples: quartz/glass; hematite/red pigments in paints;
talc/cosmetics; calcite/natural cement; mica/paint;
limestone/buildings.
4.
Mineral
Hardness Scale
Very
soft: a fingernail scratches the mineral'
Soft:
a penny scratches the mineral
Medium:
a steel nail scratches the mineral
Hard:
the mineral scratches glass
5.
Ask students if they think the crinoid should be the
official state fossil? If you think so, have them write a
letter to a local legislator asking him or her to help you
make it official.
Resources:
Cooper,
Tom, Exec. Ed. Iowa's Natural Heritage. Iowa Natural Heritage
Foundation and Iowa Academy of Science. Ames: Iowa State
University Press, 1982
Fenton,
C.L. and M.A. Fenton, The Fossil Book: A Record of Prehistoric
Life, Garden City, N.Y.: Doubleday & Co., Inc., 1959.
Iowa
Department of Natural Resources, Geological Survey Bureau, 109
Towbridge Hall, Iowa City, Iowa 52242-1319, 319-335-1575.
Additional Educational materials available upon request.
Prior,
Jean C. "Fossils." Iowa Geology 1993, No. 18: pp.
14-19.
Prior,
Jean C. Landforms of Iowa. Geological Survey Bureau. Iowa
Department of Natural Resources. Iowa City: University of Iowa
Press, 1991.
Prior,
Jean C. "State Parks - Crossroads with the Geologic
Past." Iowa Geology 1989, No. 14,: pp.9-13.
Witzke,
Brian J. "Fossils: Evidence of Ancient Life in Iowa."
Iowa Geology 1983, No. 8:pp.4-9.
Witzke,
Brian J. "Iowa's Ancient Seas." Iowa Geology 1989, No.
14: pp.4-8.
Books
& Articles: Primary-Intermediate Level
Allison,Linda,
The Sierra Club Summer Book. San Francisco: Sierra Club Books,
Little,Brown and Co., 1989.
Frankel,
Lillian and Godfrey Frankel. 101 Best Nature Games and Projects.
New York: Sterling Publishing Co., 1959.
Kohl,
Mary Ann F. And Cindy Gainer, Good Earth Art, Environmental Art
for Kids. Bellingham, WA.: Bright Ring Pub. 1991.
Mathias,
Marilynne W. And Robert A. Johnson. Earth Below and Sky Above.
Sycacuse, N.Y.: New Readers Press, 1983.
Milford,
Susan. The Kid's Nature Book, 365 Indoor/Outdoor Activities and
Experiences. Charlotte, VT: Willaimson Pub., 1989.
Ranger
Rick's Naturescope: Diving Into Oceans. Geology - The Active
Earth, National Wildlife Federation, 1412 16th St. N.W.,
Washington D.C. 20036-2266.
Riesser,
Sharon and Linda Airey, "Will My Fossil Float?"
Science and Children, 31 (Oct. 1993): pp. 42-43.
Rubin,
Penni and Eleanora Robbins. What's Under Your Feet? Earth
Science for Everyone Activity Book. U.S. Geological Survey (U.S.
Dept. Of Interior), Sup. Of Documents, Washington D.C. 20402,
1992.
Schlenker,
Richard M. And Sarah J. Yoshida. "Learning about Fossil
Formation by Classroom Simulation." Science Activities 28
(Fall 1991): pp. 17-20.
Stein,
Sara. The Evolution Book. New York: Workman Pub., 1986.
Van
Denman, Barry A. "The Fall Collection." Science and
Children 22 (Sept. 1994):pp-20-21.
Books
and Articles: Secondary Level-Adult
Anderson,
Wayne I. Geology of Iowa. Ames: Iowa State University Press,
1983.
Brown,
Vinson, The Amateur Naturalist's Handbook. Englewood, N.J.:
Prentice-Hall, Inc. 1980.
Case,
G.R. A Pictorial Guide to Fossils. New York: Van Nostrand
Reihnold Co., 1982.
Gwynne,
Charles S. "B.H.Beane and the legrand Crinoid
Hunters." Annals of Iowa 35 (1961):pp.481-485.
Hamblin,
W. Kenneth. The Earth's Dynamic Systems. 4th Edition.
Minneapolis: Burgess Pub. 1985.
Horick,
Paul J. Minerals of Iowa. Iowa City: Iowa Geological Survey
Educational Series II, 1974.
Norstrud,
Karen Beane. "Crinoids in the Sugar Bowl: Remembering My
Grandfather, Ameature Paleontologist B. H. Beane."
Palimpsest 76 (Spring 1995).
Swaim,
Ginalie, "Underwater Iowa - Where Graceful Crinoids Once
Swayed in Ancient Seas." [photo essay] Palimpsest 76
(Spring 1995).
Troeger,
Jack Clayton. From Rift to Drift: Iowa's Story in Stone. Ames:
Iowa State University Press, 1983.
Wolf,
Robert C. Fossils of Iowa, Field Guide to Paleozoic Deposits.
Ames: Iowa State University Press, 1983.
(Next
to each resource below is the location where it can be found;
AEA stands for Area Education Agency, SL is the State Library)
Film,
Video: Primary-Intermediate
At
Home on the Barrier Reef, Video, 15 min., SL-VH12448, AEA-16413.
Life
in a Tide Pool, Video, 13 min. AEA-19069.
Plant
or Animal, Video, 15 min., SL-12768.
Rocks,
Fossils and Earth History, Video, 16 min., AEA-52920.
Film,
Video: Secondary-Adult
Building
Bodies. (Marine Invertebrates). Video, 58 min., SL-VH9650
Earth:
Discovering It's History. Video, 15 min., AEA-237.
Echinderms:
Sea Stars...Relatives. Film, 12 min., AEA-44219.
"The
Little Sioux River, Pt.1." (Land Between Two Rivers:
fossils). Video, 30 min., AEA-5387.
Life
Below. (Marine Life). Video, 15 min., AEA-17638.
Magic
in the Rocks. (Fossils). Video, 38 min., SL-VH13109; 60 min.,
AEA-19089.
Mysteries
of the Hidden Reefs. (Marine Life). Film 22 min., SL-MP3095.
Oceans.
Video, 55 min., SL-VH9635.
Putting
Flesh on Bones. (Fossils). Video, 36 min., SL-VH13110.
Rocks,
Fossils and Earth History. Film, 16 min., SL-MP3057.
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