often due to various forms of disturbance such as animal burrows or later site
use where older material has been brought to the surface, for example during
the digging of foundations for a building, which can cause the order of
contexts to be transposed). If the site is relatively undisturbed, there may be
artefacts found in each context which can provide an approximate date for it–
a coin, a potsherd–so that the different events represented in the stratigraphy
can be assigned a chronological context as well as a spatial one.
The final result should be that enough information has been gathered for it
to be theoretically possible to make a virtual reconstruction of the whole site,
even after it has been completely excavated.
In cases of crime, the stratigraphic sequences can be used to establish a
sequence of events, for example during the disposal of a body. Was a hole
prepared in advance, or dug at the time of disposal? If an identifying object is
found in the layers, was it dropped accidentally by the murderer, or could it
have be deposited by someone quite innocent of the crime at another time?
Many new forms of analysis are available nowadays to aid archaeological,
and by extension, forensic interpretation of a site. It is possible to recreate
whole climates and environments, as well as activities, on a site by looking at
the soils, insects, pollen and other natural materials it contains.
Types of analysis
Soil chemistry varies according to the underlying rock types, the way in which
soils have been deposited (by wind, water, or human intervention), and the
activities that have taken place on each soil surface. Soils may be eroded over
time, but more often they build up, layer on layer, as plants die and rot back
into the earth. Soils which have been cultivated with ploughs or spades have a
different consistency from soils that have stayed undeveloped, or which have
been covered by buildings or paving and may contain different chemical
elements as a result. For example, soil that once formed the floor of a stable or
a byre will have a higher level of phosphates than soils outside, as a result of
urine from cattle or horses; sodium and potassium levels will be higher where
there has been a hearth or a kiln where wood has been burned, or where an
attempt has been made to destroy evidence of a crime by burning.
Traces of plant material can also be identified for similar purposes by
archaeobotanists. A special form of study is palynology–the study of pollen
grains. Pollen grains come in a vast array of shapes and sizes distinguishable
under a microscope, making them identifiable at a species level in many cases
(Figure 1). Pollen is remarkably durable, often lasting for many thousands of
years, and each pollen type is subtly different, enabling very precise
ARCHAEOLOGY, HISTORY, CRIME AND PUNISHMENT