BACKGROUND:
The agents of erosion (water, wind, ice, heat) remove particles from a
parent rock. These loosened particles are named by their size. Large
particles are called boulders and cobbles, smaller particles sand, and the
smallest silt and mud. When weathering and erosion begin, the loose material
consists of a wide range of particle sizes. However, as erosion progresses,
the larger particles break down to smaller sizes. The amount of sand thus
increases as erosion continues. Geologists have assigned specific particle
diameters to each of these categories.
Sand has been used to describe many human qualities. A vagabond has been
referred to as "driftless like ...sand;" endless time is
"sand that drifts forever;" we are all but a "grain of sand
on the beach." Children can spend endless hours on the beach, creating
sand castles, or digging to reach the other end of the world. It can cover
you up, but not make you dirty. Sand is clean to play with. Children look at
sand falling through an hour glass fascinated by every grain that falls and
some paint with different color sands to create works of art. Sand is loved
so much by children that adults have created sand boxes, so their children
can play.
Its funny to think that sand can be associated with two very opposite
climatic conditions. Water that crashes upon beaches along the ocean, lake
or river with the hot sun and wind that shifts sand in deserts like Death
Valley and the Sahara Desert. But if you understand the process that creates
sand, you can see that in both situations some kind of erosion of the
surrounding rock is creating the sand.
Sand is but the Earth in miniature. Every rock which makes up the earth,
succumbs to erosion and will become sand with time. (This process is part of
the rock cycle.) Mighty mountains are slowly chipped away by natural forces
like wind and rain; and over long periods of time, the mountains will become
sand.
PROCEDURE:
- Read the following two poems to the students.
LITTLE THINGS - Julia A. Fletcher
Little drops of water,
Little grains of sand
Make the mighty ocean
And the pleasant land.
Thus the little minutes,
Humble though they be,
Make the mighty ages
Of Eternity.
SAND DUNES - Robert Frost
Sea waves are green and wet,
But up from where they die
Rise others vaster yet,
And those are brown and dry.
They are the sea made land
To come at the fisher town
And bury in solid sand
The men she could not drown
She may know cove and cape,
But she does not know mankind
If by any change of shape
She hopes to cut off mind.
Men left her a ship to sink:
They can leave her a hut as well;
And be but more free to think
For the one more cast-off shell.
Discuss the poems with the students. Point out that both poems deal
with erosion.
- Following your discussion you may have students write their own "erosional
poems." This activity might be more successful if students work in
small groups.
