A walk in the wet sand at the beach
can demonstrate how the spread footings
of a building distribute the loads
they carry. It can also show what role
water plays in soil.
Footprints are made when your body
weight presses down and displaces the
water in the sand under your feet.
This allows the sand beneath your feet
to sink. Also, the displaced water
increases the moisture content of the
sand alongside your footprints. This is
why the sand changes color.
Your feet are like building footings
in the way they affect the soil both
directly beneath and alongside of
them when they carry weight. Footings,
too, affect the soil all around
them and the moisture content