The Science of Archaeology
modern excavation site.
The word Archaeology means "The study of everything
ancient." It is the science that looks into man's past to determine
how our ancestors lived and why they did what they did.
Though man has always had an interest in what
previous generations were doing (the Egyptians took the trouble
to record inscriptions off of tombs that were already centuries
old) it is only in the last few hundred years that scientific
archaeology has developed. During much of the 18th and 19th
centurys' archaeology consisted of not much more than digging
into promising sites hoping to find buried treasure or valuable
artwork for museums.
Dr. Heinrich Schliemann was one example of this
type of archaeologist. Though Schliemann brilliantly deduced
the location of the ancient city of Troy
based on descriptions from the ancient poem The Iliad,
he failed to excavate it properly and set off on a treasure
hunt that ironically destroyed much of the remains of the city
that he found so interesting.
Archaeologists today are interested in much more
thatnjust treasure. They want to examine a site and determine
what the day-to-day lives of the ancient people were like. For
this reason, archaeologists often find that the garbage pits,
which show the remains of objects used in everyday life, are
often the most interesting part of an excavation.
Where to Dig
Much of Archaeology is done though excavations.
Scientists find a likely site, then dig down in the soil looking
for ancient objects that are buried there. Sometimes the objects
wind up in the ground because they were thrown away (as in the
case of a broken pot), accidentally dropped (as with a coin)
or purposely buried (as in a tomb).
Tombs have always been excellent places for archaeologists
to learn about a people. Buried bodies can be examined and often
give important clues to the health of the former owners (Mummies
have shown that the ancient Egyptians had problems with worms,
arthritis and lung problems from sand and smokey fires). Also,
the customs of some societies dictated that the person be buried
with personal items, household effects, treasures and sometimes
even servents. These remains can be studied to learn about the
culture of that group. Unfortunately many tombs were robbed
in ancient or recent history, depriving scientists of the valuable
information they contained. In a few cases however, like the
tomb of King Tut in Egypt and the Lords
of Siapan in Peru, the graves have been excavated mostly
Scientists have a number of different methods
to determine a likely place to start an excavation. If an archaeologist
is studying the recent past, like the 19th century, he may find
many of the buildings used at that time (perhaps an old factory
or house) still standing. Even some buildings thousands of years
old can still be visible if they were built well with stone,
like Egypt's Great Pyramid. Even if no walls are standing, an
ancient city or temple can often be identified by looking for
a low, regularly-shaped hill (This is how Schliemann located
the city of Troy).
Low, regularly-shaped hills or mounds of earth
can indicate a place where people have lived for a long time,
perhaps a city. As parts of the city are torn down and rebuilt
over time, the old rubble is often used as fill or foundation
for new structures. Over hundreds and hundred of years this
can create a layer effect. As scientists dig down through the
mound, they see various layers for each rebuilding of the city.
If a city is around for a thousand or more years, a dozen layers
may have built up, with each layer representing a different
period from the history of the city.
Sometimes even when the remains of an old city
can't be seen from the ground, it can be seen clearly from the
air. Slight depressions in the soil over an old ditch or a bank
over an old wall maybe seen from an airplane in the early morning
or evening when shadows are long. Crop marks can also give clues
to buried features. Plants will grow shorter and more yellow
over buried walls and taller and greener over old ditches and
pits. As the world has gone more high-tech, so have the methods
scientists use to find old buried ruins.
Infrared photographs taken from a plane can detect
temperature differences on the surface of the ground due to
buried features. It is possible also to detect underground features
by using probes to measure the electrical resistance of the
soil or changes in the Earth's magnetic field. Sometimes finding
a site depends not on observations made at the site at all,
but by carefully studying old records and documents, or tracing
Running an Excavation
Once a site is chosen for a dig, the excavation
must be carefully planned and executed in order to get valid
scientific results. The lead Archaeologist on a dig must examine
the location and draw up a plan that specifies the areas he
wants to dig up, and the amount of equipment and people he will
need to conduct the work. Permission must also be obtained from
the landowners and governments involved.
The lead archaeologist might decide to dig a
wide, shallow pit if the location was used recently for a short
time since it is unlikely any artifacts would be deeply buried.
On the other hand, he might decide on a deep, narrow trench
if the site may have been used for hundreds of years and many
layers have been built up.
The most important aspect of a scientific excavation
is record keeping. For that reason the site is divided into
a grid of squares sometimes using stakes and string. As the
scientists dig into the soil and unearth objects, each is cataloged
with the location where it was found by using the grid number
and how deep it was found. The object is also photographed and
cleaned. A drawing is made showing precisely where within the
square of the grid the object was located. This information
will allow scientists to later piece together what the object
may have been used for and why it was buried in that position.
In general, the farther underground an object
is found, the longer it has been buried. At a site that has
been occupied for a long time, the lower layers represent earlier
periods. By knowing what layer an object was found in, an archaeologist
can estimate its age. Often this is done by figuring out what
other objects are found in the same layer. It is easy to put
a date on things like coins, pottery and charcoal. This helps
give a time to other objects found in that same layer. Record
keeping is very important to this process since it imperative
to know what items were found together on the same level.
Digging at an archaeological site is done slowly
and is hard work. Much of the work is done with trowels, or
even spoons. When objects are found, small brushes are used
to clean off the remaining dirt without damaging the artifact.
Nothing, no matter how small, is missed. Even
the dirt is carried to a place where it is sifted to find little
items the diggers may have missed with their eyes. After being
completely checked, the dirt is put into a pile known as the
One of the most common items found at an ancient
excavation is pottery. Since pots break easily, are cheap to
make and hard to repair, they are often thrown out. Fortunately
for scientists, even though pottery breaks under very little
pressure, it does not decay when buried. This means an archaeologist
can count on finding thousands of pieces of pots at any site
that has been used for a length of time.
A people's pottery tells a lot about them. For
example, the level of their technology. Did they use a pottery
wheel to make the pots or a mold? Were the pots fired in a low
or high temperature kiln? The style of the pottery and decorations
can tell scientists about the culture of the people. Was the
pot made locally or did it come from some distant land via a
trade route? Was the pot simple and cheaply made or elaborate
and expensive? The color of the pot and the minerals in the
material can give scientists a clue to where the clay it was
made from came. Since different peoples used different styles
of pottery it is also possible to trace the movement of that
people across regions by the pottery they left behind.
Getting the Date
It is important for scientists to be able to determine
when an artifact was made. There are a number of techniques
to do this, the most obvious being written records.
In places like Egypt where many records were carved
into stone monuments, it is possible for researchers to put
together very accurate chronology based on this information.
The Egyptians were great astronomers and records they made of
the movement of the stars have been used to pinpoint dates in
What about places where there are no written records?
In some cases it is possible to figure out dates by looking
at pottery that was brought in from a neighboring land where
there were written records. Since pottery styles will change
over time, the pots can be traced to estimated dates.
There are also scientific tests that can determine
the age of some objects. Organic matter (material that was once
living) can be dated to when it died by the amount of carbon-14
within it. The radiocarbon test detects
more carbon-14 in more recent objects, and less in older objects.
Measuring the amount of fluorine and other material
in bones can give the relative ages of the bones, though it
does not give a fixed calender date. The test can be useful
for comparing the ages of two bones and was responsible for
detecting the infamous Piltdown Man hoax.
Thermoluminescence tests can be used to date pottery
by detecting radioactive materials in the object and measuring
minute amounts of light given off by them. Ruins composed of
clay can be dated through magnetic dating. Over time the Earth's
magnetic north has been moving. When clay is baked, an imprint
of the Earth's magnetic field is locked into it. As long as
the clay has not been moved scientists can determine when it
was baked by measuring the difference between the magnetic imprint
in the clay and known past locations of the Earth's magnetic
One of the simplest ways of estimating the age
of wooden objects is through their growth rings. If a tree is
cut open, its growth rings become visible. For each year that
has gone by, the tree's cross-section has another ring in it.
Whether it had been a good year for the tree, or bad, it is
visible in the rings. Narrow growth rings can mean a drought.
By matching a pattern of growth rings in an object with trees
that are still living in the area where the object was made,
it is possible to come up with a very accurate date for the
As more high-tech tools become available, an archaeologist's
ability to discover old ruins and relics increase. Photo's taken
from space were key to discovering the lost city of Ubar in
On the other end of the scale, microscopes can
be used to identify pollen grains of different plants that lived
in an area. This can be used to identify farm fields, or other
changes in the foliage at a site over time. Using these techniques,
scientists have put together a clear and quite chilling picture
of the slow deforestation of Easter Island
over the centuries even though there are no written records.
underwater excavation site.
(Copyright Lee Krystek,
One of the most promising areas recently opened
by technology is undersea archaeology. Exploring the ruins of
sunken ships or submerged cities can be extremely expensive
and dangerous, but the results can be remarkable. Because the
location is underwater it may have laid undisturbed by looters
and curiosity seekers through out many centuries. In some cases
the cold water may have also helped preserve remains.
In shallow water, around one hundred feet deep,
divers wearing aqualungs can excavate a shipwreck much as they
do on land. The area is divided into a grid to help with record
of where each artifact is found. If any of the ship's hull remains,
the divers may first dig around it. This will tell them if the
wreck is stable. Sometimes nothing of the ship itself has survived,
but only its cargo.
Large amounts of muck can be moved off the bottom
by use of an air lift. An air lift is a long large tube that
works like a vacuum cleaner. Compressed air is fed into the
nozzle and as it shoots up the tube a suction is created. For
more delicate work divers wave their hands or use soft brushes
to clear silt off of artifacts.
Artifacts, like coins, after long periods in the
water can become stuck together as heavy solid clumps known
as concretions. Aboard ship the concretions can be broken
up with hammers or chemicals. To lift large concretions and
other heavy items to the surface, bags are attached to the objects
and then filled with air from extra air tanks. The bags become
balloons and lift the items to the surface.
To operate at great depths archaeologists must
use submarines, remote cameras and special diving suits that
can withstand the high pressures of deep waters. It was these
methods that allowed scientist Robert Ballard to discover the
resting place of the ship Titanic in 1985 almost three-quarters
of a century after it had been sunk by an iceberg and sank in
New and better techniques will continue to help
archaeologists, but the key to understanding mankind is not
with the technology alone, but through the dedication and hard
work of archaeologists around the world.
Krystek 1999. All Rights Reserved.