This week's experiment is a
combination of ideas. The seed for this idea came from a homeschooling list
member that wanted information on soil testing. They wanted to test and
compare soils from different parts of the country. Connected to this was
all of the information that we got on paleoecology while digging
dinosaur bones. The sediment around a fossil can tell us quite a bit about the
environment where it was deposited. To do this experiment, you will need:
a large jar with a tight fitting
lid water soil crayon or grease pencil
Fill the jar about 2/3 of the way
with water. Then add enough soil to bring the water level up to about an
inch from the top. Put the lid securely onto the jar and shake it vigorously
for about a minute. You want to be sure that all of the particles in the soil
are loosened and that there are no clumps left.
Once you have everything very
well mixed, place the jar in a place where it can sit for 24 hours without
being disturbed. Watch it carefully. After one minute, use the crayon to make a
mark at the top of the sediment that has settled out. This is the sand
part of your soil.
Let the jar continue to sit
undisturbed for one hour. You will notice that more of the sediment has settled
out. Mark the top of the new layer. This layer is made up of silt sized
particles.
Again, let the jar stand without
being moved or jostled. I know it is hard not to pick it up and look more
closely at the layers. Have patience and wait. After 24 hours, most or all
of the sediment should have settled out, leaving clear water above the
sediment. This last layer is the clay part of your soil. It has the tiniest
particles and takes the longest to find its way to the bottom. Make a mark at
the top of the clay layer.
Now that you have separated your
soil into sand, silt and clay, you can determine what kind of soil you
have. At my house, this is a quick, easy experiment. Living at the beach,
we have very sandy soil, with almost no silt or clay.
You may have loam soil, which has
fairly even amounts of sand, silt and clay. This is the ideal kind of soil
for your garden. It has plenty of nutrients and drains well.
If your soil has mostly clay,
then you have (can you guess?) Clay soil.
In addition to seeing the make-up
of your soil, this experiment can also give you an idea about the environment
where different kinds of sediments are deposited. Some of the dinosaur
bones that we were digging were found in layers of sand, while at another
site, there were bones in a layer of clay. From our experiment, we can begin
to think about what the areas were like when the bones were buried. The
clay layer would seem to indicate still water, sitting in a swamp or
marsh, while the ribbon-like layers of sand look to have been flowing streams.
Back
to Krampf Index Including permission to post
these
experiments on my web site.
