Simon Fraser University of Archaeology and Ethnology
You might be wondering by now, why most of the artifacts we find
during excavation are made of stone. This is simple: stone lasts a long time!!
On the other hand, most things don't last so long.  They decay or decompose.
You probably knew this already, if you didn't, try putting a rock on your windowsill,
beside the rock try putting an apple core.
Wait a few days, but don't wait too long or things will start
to smell! What you are smelling is the apple starting to decompose.
The rock, however, is still the same as when you put it there.
This happens because rocks are inorganic (not living) and
plants are organic (living).
Inorganic stuff takes much longer to break down or decay then organic things.
Eventually, everything breaks down though, even the biggest mountains will turn to sand.
In archaeology, though, we find a lot of inorganic remains
like stone tools and stone fireplaces (hearths) and stone benches and beds.
 What we don't find a lot of is organic stuff like food or cloth - this is because it has decomposed in the ground way before we got there!
Lucky for us though, the speed at which organic stuff decomposes
changes, depending on what it is and where it is located.
Sometimes, organic material can last a very long time,
as you may have seen in 1997's tip page on the Ozette site
where wood was kept underwater and lasted for a very long time.
In some circumstances even very, very old material can be preserved.
For example, prehistoric grain is often found carbonized (turned into charcoal)
by fire and archaeologists can identify it thousands of years later.
Bones only last well in certain soils. The soil here on the Northwest Coast
isn't very good for preserving bone, so we don't find a lot of it.  In Africa, though, the
sand is so dry that bones can last for millions of years!
This is a picture of some bones in the laboratory:
bones in the lab
What we do find a lot of on the Northwest Coast of B.C. is shell.  Shells make the
soil less acid and so organic stuff found in piles of shells (called shell middens),
often preserves very well.
Dry and hot like Africa, freezing like the Arctic and waterlogged
like at Ozette all help organic material survive very well.
Organic material is very useful to archaeologists. It can help us understand
what the people in the past were eating or wearing or making as art.
In our area of the world, this is difficult because our soils don't preserve organic
remains very well. Also, because we have so many trees, many things like
houses and art and clothing were made out of wood. These things usually
decompose before archaeologists ever find them.
Oh well, we'll find other stuff to help us do our
jobs as archaeological detectives, right?