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SOILS AND ARCHAEOLOGY
The disciplines of soil science and
archaeology make a natural combination to study landscapes and
environmental history of sites from previous civilizations.
Archaeologists have been excavating sites for centuries, but
scientific excavations have only taken place for perhaps the
last 70 to 80 years. Soil science has been involved in
archaeological excavations for 50 to 60 years in the United
States, but in the early years only soil chemistry was used to
evaluate the impact of humans on the soil system. In the last
few decades, more sub-disciplines of soil science have become
interested in the archaeology, especially pedology (study of
soil formation and classification). In many archaeological
projects, pedology is one member of a team of scientists
studying a site; team members may include scientists from
geology, botany, zoology, palynology, surveying, and other
disciplines.
Perhaps a definition of soil is in order to
establish the boundaries and general nature of this natural
resource. Soils are defined as natural bodies on the earth’s
surface with unique morphological characteristics resulting from
past or present combinations of physical, chemical, and
biological weathering processes. The upper boundary is clearly
defined but the lower boundary is quite variable; generally
soils include the upper 2 meters of the earth’s surface. Soils,
however, will vary from just a few centimeters in thickness to
20 to 30 meters in some areas of the tropics. This upper surface
of the earth’s crust is where most of the archaeological
activity takes place and thus the interest in soils.
 The applications of soil science to
archaeology used in this article come from the study of al-Mudaybi’,
a Moabite fort, and from the survey of sites on the Karak
Plateau in Jordan. The soil investigation was initiated in 1997
and continued in field seasons in 1999 and 2001. These field
seasons provided many examples of using soil interpretations for
clarifying the archaeological settings and specific
stratigraphic characteristics of sites. In this article we will
provide some general information on soils and landscapes and
their application to archaeological investigations. A general
study of the soils on the Karak Plateau is available in an
earlier VKRP article (Foss, 2002)
http://www.vkrp.org/studies/environmental/plateau-soils/
The study of soils at archaeological sites includes two major
components; these are the (1) field study of landscapes and
description of individual soil profiles and (2) laboratory
characterization of soils. The field study comprises a vital
aspect for all future interpretations of stratigraphy and
ultimately the environmental history of the site. Field soil
morphology includes detailed evaluation of soil horizons that
provide descriptions of soil texture, structure, color,
consistence, horizon boundaries and classification. Figure 1
shows a soil profile (cross section of soil) in Field A at al-Mudaybi’;
note the alternating dark and light-colored bands in the lower
portion of the profile. The dark layers are periods of stability
when organic matter was accumulating in the soil from plant
decomposition, and light-colored zones are areas of rapid
deposition of wind-blown sediment. Many archaeological sites are
in a dynamic position on the landscape, such as along rivers and
streams, base of colluvial slopes, or in areas of eolian (wind)
deposition. Loess deposits (Figure 2) were the dominant parent
material for soils on the Karak Plateau, although a wide range
of loess thickness occurs on the various landscapes.
 Laboratory characterization of soils for archaeological
interpretations is used to verify and supplement the field
morphology of soil profiles. In addition, laboratory analysis
can provide information on soil system modification resulting
from human occupation. One of the best examples is the amount of
Pb and other heavy metals introduced into soil systems during
Roman times in the Mediterranean region. |
