Methods or archaeological investigation
 Your task
Read about the different methods of archaeological investigation and
complete a table similar to the one below.
Type of investigation
What it can reveal
Problems / Limitations
Imagine you have been asked to investigate the following sites. What sorts of
evidence would you look for and what methods would you use to find out the
age of the site and the people who lived there?
A Roman villa has been uncovered on the cliff tops near the Warren.
The fields around Sugar Loaf Hill show some strange lumps and
bumps
A walker in a field near Hythe has found some sherds of unusually
coloured pottery
A dog discovers a bone buried in the woods near Lyminge
Following a powerful storm, the wreckage of a ship is revealed under
the sands of a beach near the harbour.
1. Plants & insects
Biologists can sometimes use their expert knowledge of
plants and animals, to build up a picture of what the
environment looked like in the past. Biological remains
give clues about what the climate was like. At the time
of the Norman Conquest an insect that feeds on nettles
was commonly found as far North as York. Today, it is
only found in southern regions. Similarly we know from
written records of important landlords that grapes were grown as far as the
borders of Wales. This information tells archaeologists that the climate was
possibly warmer than it is today.
Wet or boggy sites can often preserve detailed information about the climate
and weather in the past. Pollen and tiny hard-shelled plant cells called
phytoliths sink to the bottom of lakes and boggy ground along with small
shelled animals and single-celled water plants called diatoms. Deposits build
up over time as sediment, particularly in winter months when flooding is more
common. These layers of sediment can be identified and dated.
Archaeologists can look at the layers and make judgements on weather
conditions, how wet some years were compared with others, the types of
animals that thrived and those whose numbers declined or became extinct.
Small insects such as beetles have hard armour around their bodies which
often is often preserved long after the animal has died. Different kinds of
insects live in different places, for example dung beetles are often found
around manure produced in fields by grazing animals, woodworm beetles
show the presences of timbers and weevils often indicate the presence of
grain and are used by archaeologists to identify grain stores.
Even human excrement and remains contains plant and insect information
that can help to identify and date remains. The bodies of Anglo-Saxons
excavated in graves near Folkestone will have contained the remains of
pollen and flies, indicating they were left on show to visitors for several days
before being buried. Human excrement found in cesspits or middens contains
seeds of plants that have either disappeared from Britain or only recently
been imported and so again can be used for dating purposes.
2. Wood
Although wood will eventually rot over time, if it is
preserved in conditions where there is very little
oxygen, even wooden objects can sometimes
survive. In the 1980s Henry VIII’s flagship the Mary
Rose was lifted from the seabed off Portsmouth,
with large parts of the hull still intact. This was
because it was covered by mud and silt which
prevented oxygen and the micro-organisms that
depend on it to survive, from getting to the timbers. Now the ship has to be
kept constantly damp in order to stop the timbers drying out and deteriorating
further.
Wood can be dated using a variety of techniques. Marks on the wood
produced by tools can tell us something about the time it was worked. For
example, the bronze age boat at Dover has evidence of axe marks along the
hull by the ancient Britons who cut the timbers used to make it to the
appropriate shape and size. Everything that was once alive contains carbon,
and this too can be used to date the age of wood. As wood gets older the
carbon inside slowly breaks down and the rate at which this has happened
can be measured by special radio-carbon dating technology. Wood can also
be dated by studying the growth rings. Each year a tree produces a new ring
of wood as it grows. Some years, due to weather conditions, trees grow more
than others and so the rings may vary in size. Comparing the growth rings of
trees of known ages with samples from archaeological sites, it is possible to
work out the age of a particular timber.
3. Surveying
Sometimes just walking over the ground of an
archaeological site can reveal a lot of information about
how it was used in the past. Lumps and bumps in the
soil often betray the presence of burial mounds called
barrows or the presence of the foundations of walls or
buildings. Aerial photography can reveal the outline of
long-buried buildings below the surface, like the Roman
villa complex at East Cliff. This is because, building rubble below the surface
reduces the fertility of the soil and plants find it harder to grow there. In
especially hot summers, the soil becomes so dry, that plants die back that are
growing above the rubble, leaving a brown or yellow trace of the building
beneath.
New technological inventions have made it possible to see what is going on
beneath the surface of the soil using a variety of techniques. Ground
penetrating radar sends waves into the soil which bounce back at different
intervals as they hit objects below the surface. Magnetometers detect tiny
variations in the earth’s magnetic field. These indicate objects below the
surface, and produce especially strong signals where there has been some
evidence of burning. More commonly, metal detectors have been used to find
metallic objects such as broaches and coins. Metal detecting is a popular
hobby among amateur archaeologists and many famous artefacts, including
coins on Sugar Loaf Hill have been found as a result. However, metal
detectorists need to report their finds to their local museum. Some
unscrupulous detectorists have sold their finds without reporting them to the
authorities and have destroyed sites of important archaeological interest by
digging them up to retrieve metal objects.
4. Computer reconstruction
Human remains can reveal an enormous amount about
the living and working conditions of people in the past.
Even if only a skull remains, the latest in computer aided
design can help archaeologists reconstruct the
appearance of the individual. The contours of a skull
reflect the layers of skin and tissue that once were on a
persons face. Marks on the surface of bone can indicate
the presence of muscle fibres and cartilage. This
information can be used in two ways to reconstruct the appearance of an
individual. Firstly, measuring pegs are placed on the surface of the skull to
indicate the depth of muscles on the face, on to top of these layers are built
up to indicate muscle, cartilage and skin. Finally, features such as hair, eyes
and ears are added. This whole process can be very time-consuming and
recently computers have been used to speed up this process. Computers can
draw on a data base of thousands of skulls and facial reconstructions, making
the process increasingly accurate. The technique is now so accurate, it is
often used by police to identify unknown bodies and create photofit images of
the individual. The technique has also been combined with X-ray technology
to look inside tombs the wrappings of mummified individuals to create a 3D
image of the person within, even if the skin tissues have shrivelled or decayed
with time.
Computers can be used to reconstruct the appearance of buildings as well as
people. Often very little remains of an archaeological site above the ground
and sometimes even the foundations of buildings can disappear as
subsequent generations ‘rob’ the site for stone and other building materials,
leaving little more than an outline in the soil where a building once stood. If
this is the case, it is hard to visualise what a particular building may have
looked like in its finished state. 3D reconstruction software, similar to that
used to make animated films has been used to plot the outline of these
buildings and use other data relating to the building to produce an image of
what the entire building would have looked like. 3D imaging software also
enables the viewer to take a virtual walk through a building to gain a sense of
the interior or to access parts of a building that would be difficult or dangerous
to visit. This technique has been used, for instance, to look deep within the
Egyptian pyramids to gain an accurate picture of hidden access shafts and
burial chambers.
5. Pottery
The very earliest settlers in the Folkestone area
dating back to pre-historic times would have
made vessels for food and water from fired clay
known as pottery. The design of these pots
changed over time as did the expertise of the
potters. Neolithic pottery of about 7,000 years
ago was actually much finer than pots made
only 2,000 years ago, which was rather thick
and badly fired. Bronze Age pottery was much
thinner with delicate patterns, Iron Age pottery has beautiful curved designs,
and so it goes on. Each age has its own characteristic designs and
techniques of making pottery. The clay that was used to make pottery can
also tell us much about where the object came from. Tiny little particles of
shells and minerals contained in the clay can reveal to the expert eye where
the pot was made in the country or indeed if it was imported from abroad. The
very latest science, using a technique known as thermoluminescence (TL)
can also be used to date pots scientifically. When a pot is fired in a kiln energy
from the breakdown of chemicals inside the clay is trapped inside. Scientists
take a small sample of this, and release the trapped energy as light. The
strength of this light is used as a measure of how old the pottery is.
Pots are also useful to archaeologists because they can sometimes reveal
what was inside them. Roman amphorae, large storage vessels, have been
found still with trace elements of the types of food inside that Romans
frequently ate – grain, wine and a very smelly fish paste!
Pottery breaks as easily now as it did in the past, and the position of pottery
fragments are always careful recorded by archaeologists. If lots of fragments
of cooking vessels are found in one location, this might indicate human
habitation or specifically the place where food was prepared. If top quality
pottery pieces or sherds as they sometimes called are found, this might
indicate the occupier of a house was of high status. The Roman villa complex
found on the East Cliff of Folkestone had sherds of Samianware inside, a very
fine type of pot imported from the Mediterranean, which could only be
afforded by the wealthiest Romans.
The types of pot found at sites also reveal much about the patterns of trade
and movement of the people who used it. Medieval sites sometimes reveal
fragments of wine jars from France and Germany showing that international
trade and travel was much more extensive than people might initially think.
6. Human remains
Human remains can tell us an enormous amount both about the life of the
individual who is preserved or the community in which they lived. Like all
organic matter, human bodies decay rapidly once they are no longer alive and
usually only the hardest material, bones and teeth, survive long after we are
dead, if a body is buried or ‘interred’. However, there have been cases where
bodies have been miraculously preserved because they have not been
exposed to air and the tiny micro-organisms in the atmosphere which would
have caused them to decompose otherwise. One of the most famous
examples of this in Britain was the ‘Lindlow Man’ discovered by men digging
peat in Lindlow in Cheshire and quickly nicknamed ‘Pete (Peat) Bog’ by
archaeologists. His body was so well preserved his facial features can clearly
be seen, including hair, ears and even his beard. As well as his skin, some of
his inner organs also survived, and archaeologists were even able to examine
the contents of his stomach and find out about his last meal. The body
revealed one last gruesome secret. Around his neck was a thin chord. The
man had been murdered as a sacrifice to the gods, before being thrown into
boggy grown, where his body sank into the mud and was conserved.
Even if bodies are not as well conserved as Lindlow Man, skeletons of
individuals can tell us a great deal. Accidents and breakages are often
revealed on the bones by lumps and grooves where the body has healed itself
over time and replaced damaged tissue. Misshapen or ill-formed bones, may
indicate the person suffered from a disease caused by poor nutrition when
young, such as rickets. Repetitive strain caused by heavy manual work is
shown in joints which are worn down. The shape of bones can reveal the
gender of a person, for example female skulls have a smooth brow whilst
male ones have a slight lump above the eye line. As the body grows, smaller
bones fuse together and so this process can be used to date skeletons. If the
ends of bones in fingers and wrists are still separate, this would suggest the
individual was no older than their early twenties. Bones can sometimes reveal
the attempts of earlier surgeons and doctors to cure patients or relieve pain.
One technique of curing migraines or brain tumours during the middle ages
was to remove a piece of the patient’s skull in an operation known as
trepanning. Skulls have been found with circular fragments of skull cut away
from the individual in the bones in the crypt at Hythe, which are almost
certainly the result of this procedure. Remember this was in an age before
anaesthetic as well!
The latest scientific techniques can tell us about the diet and even location of
an individual as they grew up. The enamel in our teeth contains water
molecules. The atomic make up of these molecules differs slightly depending
on where the water fell which the individual drank as a child as their teeth
were forming. Information about these differences has been gathered together
from all over the world, and now cane be used to pinpoint within a matter of
miles where an unidentified individual originally came from. Police have used
this technique to help identify accident or murder victims.