Tectonic
plates
are
large
____________________
of
rock
that
make
up
the
foundation
of
the
Earth's
crust
and
the
shape
of
the
continents
.
The
tectonic
plates
comprise
the
bottom
of
the
crust
and
the
top
of
the
Earth's
____________________
.
There
are
ten
major
plates
on
Earth
and
many
more
minor
ones
.
They
float
on
a
plastic
-
like
part
of
the
Earth's
mantle
called
the
____________________
.
The
plates
are
most
famously
known
for
being
the
source
of
____________________
.
The
____________________
plates
are
about
100
km
(
60
miles
)
in
thickness
,
with
continental
plates
tending
to
be
thicker
than
____________________
ones
.
The
composure
of
the
two
types
of
plate
is
also
quite
different
.
Oceanic
plates
consist
of
thicker
basaltic
rocks
,
compressed
by
the
pressure
of
kilometers
of
water
.
____________________
plates
have
a
lower
average
density
,
containing
granitic
rocks
with
a
heavy
composition
of
aluminum
and
silica
.
The
mantle
underneath
the
____________________
plates
is
constantly
recirculating
,
causing
the
plates
to
float
around
slowly
in
a
process
called
tectonic
drift
.
This
process
was
described
well
by
the
theory
of
plate
____________________
,
which
solved
several
scientific
dilemmas
about
the
distribution
of
____________________
when
it
was
introduced
.
When
plates
push
up
against
each
other
,
they
create
mountain
ranges
and
____________________
.
Mt
.
Everest
was
created
in
this
way
.
