Transcript Sorting of Earth According to Density

Sorting of Earth According
to Density
How Do The Densities of Earth's
Layers Compare?

Knowing that some things float on
water while others sink gives us a
good idea about how density relates
to things around you. Not only does
density determine when something
will sink in water, it also is
responsible for the different layers
on the Earth!
How Do The Densities of Earth's
Layers Compare?

Below you will find photographs to represent the different
layers of the Earth. At the right of each photograph you will
find the density for that layer.
B
A
C
Density =
.0013
g/cm3
Density D
varies
between 13.0
g/cm3 at the
core to 4.5
g/cm3 at the
mantle.
Density =
3 g/cm3
Density =
1 g/cm3
Sorting according to density in
Nature
Can you think of any examples of
sorting according to density in
nature?
 Streams
 Road Cuts
 Beaches

The Beach


Have you ever walked
along a beach and
wondered why parts of it
were sandy and other
parts of it were rocky?
Why does this happen?
When the waves hit the
beach, the sand and rocks
carried in the water fall
out. The denser rock
particles are dropped first
along the shore, while the
less dense sand particles
are carried up further on
the beach.
A stream or river

Try and think of
the rocks you have
observed in a river
or stream. Where
do the big rocks
go? Where does
the smaller stuff
like sand go?
Sorting
Have you ever come across a smooth pond like the one below? It
just seems to ask you to "skip a rock on the surface!" You know
that when the rock stops skipping, it will sink beneath the surface.
What makes rocks sink while leaves or twigs float in water?
Sorting in General

Dense objects like large
rocks stay at the bottom
while lighter objects like
silt and dirt can be carried
away by the flow. Density
affects the sorting of
naturally occurring
materials in a mixture.
Quiz

Pat puts items into a jar and shakes it up. Pat lets the jar
settle for 5 minutes. What would be the expected order of
the items going from the top of the container to the
bottom?
a.
b.
c.
d.
rock, sand, water, metal
metal, rock, sand, water
water, sand, rock, metal
sand, metal, water, rock
Quiz

Water has a density of 1.0 g/mL. You are given a
rock with a density of 2.5 g/mL. Predict what will
happen to the rock when put into a container of
water.
a. The rock will sink to the bottom of the
water.
b. The rock will float on top of the water.
c. The rock will sink half way to the bottom
of the water.
d. The rock will float just below the surface
of the water.
Quiz
Why is water located above the crust
but below the air?
a. The density of water is higher than air and
higher than the crust
b. The density of water is lower than air and higher
than the crust.
c. The density of water is higher than air and lower
than the crust.
d. The density of water is lower than air and lower
than the crust.
Quiz
Which of the following statements best explains
why earth is layered in the following order:
air  water  crust  core?
a. Things in nature like to order themselves by color, red to
the bottom and blue to the top.
b. Things in nature like to order themselves by density, most
dense to the bottom and least dense to the top.
c. Things in nature like to order themselves by particle size,
largest particles to the bottom and smallest particles to the
top.
d. Things in nature like to order themselves by temperature,
hottest to the bottom and coolest to the top.
Quiz
A beach is composed of particles of
sand of the same size. Why doesn’t
the beach have materials of all sizes?
The particles have
a. come from the same place.
b. come to the beach at the same time.
c. been found in underwater canyons.
d. been sorted by size and density.
Quiz
A streambed contains round rocks, all about
the same size. Why are there no smaller
particles of sand and clay? Sand and clay
a.
b.
c.
d.
is denser.
have washed away.
were never there.
are too small to see.
Quiz
During a flash flood, large boulders
can be moved downstream. Why
don’t large boulders usually move?
a. They are made from very dense
materials.
c. They are attached to the stream
bottom.
d. They are weathered and eroded in
place.
Quiz
Where would the smallest particles of rock
be found in a streambed?
a.
b.
c.
d.
In the strongest current
In the weakest current
Near the middle
At the beginning
Quiz
In an experiment, students shook jars of
water with soil and rock in them. What
does the shaking model represent in
nature?
a.
b.
c.
d.
A lake environment
A stream current
Living things in an environment
A rainstorm
Quiz
Sand with particles of the same size was
gently shaken in a jar to see if layers
would form. What variable was being
tested?
a. particle size and density
b. particle color
c. particle type
Quiz
A student shakes a jar with a mixture of
sand types. Instead of mixing, the sand
grains separate into layers. Why?
a.
b.
c.
d.
The grains are different colors.
The grains have different shapes.
The grains have different densities.
The jar has a round shape.
Quiz

Water is added to a jar with soil in
it and the jar is shaken. Which
drawing shows what will happen
after it sits for a few minutes?
Quiz
In the spring, rivers in Utah are often brown
in color. A sample of the water shows it
contains very small particles of silt. Why
is silt suspended in the water?
a.
b.
c.
d.
Silt is in brown in color.
The water is moving rapidly.
Silt is small with low density.
Water has a high density.