4 layers of earth
crust
mantle
outer core (liquid)
inner core (solid)

a static tilt exists
between the rotational axis
of the inner core
and the mantle

causes an 8.5 year
inner core wobble
in polar motion
and daily rotation

this creates
greater densities
in the outer core
at the inner core boundary

the liquid outer core is caught between the differences
in motion of the mantle
and the inner core

affecting
the outer core shape
and fluid motion
driving dynamic changes
in the earth's interior