Download Constructive Erosion: Soil Questions

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Constructive Erosion: Soil
By Cindy Grigg
Erosion is a natural
process that moves rock,
sediment, and soil from
one place to another.
Erosion wears away rock.
Erosion carries away bits
of land. Flowing water
can cut a gully or a canyon.
Winds can blow away
sand from beaches or
topsoil from farm land.
You might think that erosion is always destructive in nature. But in
a way, erosion can be constructive, too. You might say that erosion
constructs soil.
What is soil? Soil starts out as pieces of rock. All of the rocky bits
that make up soil started out as much bigger rocks.
How do big rocks get smaller? As years and years pass by, the
rocks slowly weather. They are broken down into smaller and
smaller pieces. Rain, wind, and ice break rock into smaller bits.
Temperature helps, too. When a rock gets hot from the sun, it
expands, or gets bigger. When the rock gets cold, it gets smaller.
Sometimes this getting bigger and smaller makes rocks break into
pieces. Ice can get into small holes or cracks in rocks. When it
freezes, it can break the rock apart. Ocean waves break down rocks
into small pieces called sand.
Soil has air and water in it. Soil is a home for some animals.
Worms, wood lice, millipedes, and many other little animals make
their homes in soil. They burrow into the soil and make spaces for
air and water.
If you fill a glass bowl with rocks, you can see air spaces among
the rocks. Soil is made of bits like the rocks. If you pour water into
the bowl of rocks, you can see how water fills the spaces. Water fills
spaces in the soil in the same way. Bits of soil hold some of the
Dissolved minerals from rocks become part of the soil. If you
pour a spoonful of salt into the water in the bowl of rocks, you might
see some of the salt. Some of it would dissolve in the water. Then
you would not be able to see it. Water in soil has dissolved minerals
(like salt) in it, too.
Matter that was once alive, called organic matter, becomes part of
the soil as it rots or decomposes. Roots, leaves, and other plant parts
rot and add organic matter to the soil. When animals die and are not
eaten by another animal, their bodies rot and add organic matter to
the soil. The decayed organic matter in soil is called humus. It adds
nutrients to the topsoil. Nutrients are materials plants need to live
and grow. Humus gives topsoil a dark color. Plants grow well in
topsoil that has humus.
Nature makes soil slowly. It can take one thousand years to form
one inch of topsoil. Plants need soil to grow in. Soil holds up plants.
Soil gives plants nutrients and water. People and animals eat plants.
We all need soil.
Constructive Erosion: Soil
Questions
1. What is erosion?
A. humus
B. organic matter
C. a natural process that moves rock, sediment, and soil
from one place to another
2. What is a part of soil?
A. air
B. humus
C. rock
D. all of the above
3. Which of these is a fact from the story?
A. It takes millions of years to form one inch of topsoil.
B. Plants do not grow well in soil that has humus.
C. Water in soil has dissolved minerals in it.
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4. ______ fill/s spaces in the soil.
A. Air
B. Water
C. both a and b
5. Ocean waves break rocks into smaller pieces called ______.
A. sand
B. soil
C. humus
6. ______ are materials plants need to live and grow.
A. Oceans
B. Nutrients
C. Humus
7. Read the first paragraph again to find meaning for the word
destructive. Which of these has a similar meaning?
A. to take apart
B. harsh
C. unhelpful
8. Antonyms are words that have opposite meanings. Which of
these are antonyms?
A. constructive, destructive
B. cold, chilly
C. ocean, water
(Summarize Concepts) Write a paragraph that tells what soil is made
of.
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Think about soil you have seen. Does it all look the same? What color
or colors of soil have you seen? Where did you see different kinds of
soil? What kind of plants were growing in each place?