47
Fossils are the traces (such
as footprints) or remains in
rocks of living things from
millions of years ago.
Sizing it up
Soil particles come in different sizes.
Imagine a clay particle as a large
coin. Next to it, silt would be as big
as a tennis ball, and coarse sand
the size of a hot-air balloon!
Sand particles
look like very
small rock pieces.
Both plants
and animals can
become fossils.
The best soil for
plants has not
too much sand
or clay.
Clay particles
look like tiny,
flat plates.
Plant food
Soil is made up of
sand, silt, and clay
particles. The amount
of each affects how
fertile soil is, how
much water it holds,
and how well water
drains through it.
S
t
o
n
e
s
c
a
n
b
e
t
r
a
n
s
p
o
r
t
e
d
a
w
a
y
f
r
o
m
w
h
e
r
e
t
h
e
y
f
o
r
m
e
d
b
y
r
i
v
e
r
s
.
Silt
Clay
Sand
I
t
c
a
n ta
k
e
e
i
g
h
t
y
e
a
r
s
f
o
r
s
o
i
l
a
s
th
ic
k
a
s
c
a
r
d
t
o
f
o
r
m
.
G
o
l
d
M
a
r
b
l
e
S
an
d
s
t
o
n
e
G
a
r
n
et
C
it
r
ine
046-047_Rocks_And_Minerals.indd 47 31/10/2019 14:05