Digging the Earth's Crust
This lesson developed by Reach Out!
Recommended Age Groups: Later Elementary, Middle School
1. What is the Earth's crust?
2. What is soil?
3. Are there different types of soil?
- The Earth's crust is made up of rock and soil material.
- Where there are low and dipping areas in the crust, we see where water
has collectedas in ponds, lakes, and oceans.
- Rivers and streams push their way along different paths on the Earth's
crust, cutting their way as they move along.
- We can see that there are solid surfaces and water surfaces on our Earth.
- The solid surfaces can be very different. Some are hard, others are
soft. Massive amounts of rock can be found in tall mountains. Much of
the solid surface is made up of what we call soil or dirt.
- We build things on soil, plant gardens and crops in soil, dig in soil,
and even tunnel under soil.
- There are many kinds of soil. We will look at seven different kinds:
clay, gravel, humus, loam, rock, sand,
- Making Observations
- Making Comparisons
- Observation Skills
- Documenting Findings
- Communicating Findings
- Pie plate or sturdy paper plates
- Access to many different kinds of soil
- Clear plastic or glass jars (large baby food jars or peanut butter jars
- Labels for soil sample jars
- Magnifying glass
- Globes and maps
- Digging spoons, trowels, spades
- Sturdy bag or box to put jars and tools in while going out to dig and
find soil samples
- Pen or pencil
Ample elbow room and place to keep soil sample jars.
Procedures and Activity
Discuss the following questions and share ideas:
- What is the Earth's crust?
- What is soil?
- Are there different types of soil?
Briefly go over these questions to come up with some basic understandings.
Review the concepts, principles, and facts listed above. Look at a globe
and find large bodies of water and large and well-known rivers that over the
years have carved a path in the Earth's crustsuch as the Grand
Canyon in Arizona.
- Make labels and put one on each jar for clay, gravel, humus, loam, rock,
sand, and silt.
- Put jars, digging spoons, or trowels in a bag or box.
- Go outside and try to get samples of each kind of soil. Put the samples
in their own jars.
- Inside, get out magnifying glass. Put a little sample of each kind of
soil in the pie plate, one sample at a time. Examine it with the
magnifying glass. On the handout, write down the color, texture, and
materials you see and find in each soil sample.
- Add a few teaspoons of water to each pie plate to make the soil damp.
Look to see what happens. Do the soil samples take in or absorb the
water? Do the soil samples become like mud? What color do you see?
Touch each wet soil sample. What does it feel like? Slimy? Sticky?
- Leave the wet soil samples out to dry on a shelf near a window. Watch
what happens to each type of soil as it dries out. When soil samples are
dry, look at them again. Is the color and texture different from when we
first dug them up? Which ones seemed to dry faster than the others?
- Think about where we would want to use these different kinds of soils.
For example, what kind of soil would you want to build a house on? A road?
Which soil would be great for gardening or farming? Why? Which soil would
you use on a nature path or walking area? Which soil is best for
sandboxes? Which soil would you want at the bottom of a pond or lake? Why?
- What is the Earth's crust?
- What is soil?
- What are some different kinds of soil?
Listen for evidence of new understandings about what the Earth's crust is,
what different kinds of soil there are, and given the characteristics of
soils, how we use them for different purposes.
- Invite a builder and a civil engineer to come in and talk about soils and
how they impact the design and actual construction of houses, larger
buildings, and roads.
- Invite a farmer to come and share information about soil and what kinds
of crops can be grown with different kinds of soil. Or, visit several
farmers who raise different crops to learn about their soil and soil
- Visit a museum like the University of Michigan's Exhibit Museum to
learn about fossils from dinosaurs, fish, plants and even insects. How
did these bones and organic materials turn into a rock material?
- Look on line at the U.S. Department of Agriculture's Soil
Survey Maps of your area (not all maps are on line yet). See whether
you can connect the soil type with what the land is being used for. For
example, certain types of soil are best for farming; some cannot support
heavy buildings; some will not permit the construction of houses with
basements, and so forth.
- Get smart about soil with S. K. Worm.
- Find out How NASA Studies
- Check out the National Soil Survey Center's Soil Taxonomy - a
description of the 11 major "orders" of soil.
- Use the Soil Science Society of America's on-line dictionary to research
anything related to soils.
- Browse the Natural Resources Conservation Service's Index to Maps, Facts,
Careers Related to Lesson Topic
- Civil Engineer
- Soil that gets hard when baked or fired, and sticky and plastic-like
when it gets wet. Light in color.
- The Earth's outer surface and layer of material.
- Soil made up of lots of little rocks and pebbles.
- Soil material that comes from the decaying and decomposing of plants,
animals, and insects. It is called "organic," is
usually a dark brown or black color, and is a very important part of
soil used for growing plants. Decayed materials provide minerals and
other food for plants growing in humus.
- Soil that is a mix of sand and clay.
- Material that is made up from the decaying and decomposing of dead
plants, animals or insects. Humus soil is made up of organic material.
- A bunch or hunk of soil, pebbles and stone material. Rock is made from
soil, stones, and pebbles being heated up and pressed upon for a very
long period of time. They are very hard and do not have humus or
organic material, so are not any good for growing plants. Rocks have a
variety of colors depending on the soil and pebbles they were made of
and the minerals that they absorbed over time from water passing over
- Loose and light soil that is formed by the breakdown of rocks.
- Soil made up of lots of little pebbles, even smaller pebbles than found
- The top layer of our Earth that we grow things in, build buildings on,
and dig tunnels under. We often call it dirt.
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Last revised 23 Jan 05