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Soil Morphology
 The
unique morphology of soils is the result of the interaction of
the five factors of soil formation; these factors include
climate, vegetation (biotic), geology, topography, and length of
time the interactions have taken place. Climate, and especially
rainfall, is particularly important to distinguish soils on the
Karak Plateau. Two profiles illustrating this factor are shown
in Figure 9; profile 1 is about 3 km north of Mutah in a
rainfall region of 500 mm/year while profile 2 east of Fajj has
an annual rainfall of <100 mm. With scant rainfall and
subsequently little vegetative matter to incorporate into the
soil matrix,
profile 2 
is very light brown while in a region of
more abundant rainfall and vegetation, the soils have
dark-colored surfaces. Erosion, of course, can result in the
dark-colored surface being removed and the soil surface may have
the color of the subsoil or geologic material.
 The color of the surface soil is an important morphological
characteristic to observe at archaeological sites. Another
example is shown in Figure 10 of a soil profile in area D at al-Mudaybi’.
Note the dark-colored layer at the bottom of the excavation;
this was the original surface during the early activity of the
fort around 700 years B.C. The location of buried surfaces in
archaeological sites is extremely useful in identifying former
living surfaces and sources of artifacts.
Other soil horizons can also aid in the interpretation of
archaeological sites. Subsoils (B horizons) such as argillic
(clay-rich) can provide estimates on length of weathering time a
soil has been exposed to the environment. Generally it requires
about 4,000 years to develop a minimal argillic horizon in a
humid environment and 10,000 years for a well-developed argillic
with a thickness of one meter. Thus, the level of subsoil
development can be extremely useful in developing site history.
At al-Mudaybi’, the argillic horizon underlying the more recent
sediments was probably developed toward the end of the
Pleistocene and is probably 15,000 years in age. Other subsoils
can also provide information on length of weathering time.
Soil morphology not only includes horizon identification and
description but also describes other soil characteristics. These
include soil texture (particle size distribution), structure of
soil units (e.g. blocky, granular, prismatic), consistence,
horizon boundary, and presence of other features. Some of the
additional features described may include the presence of free
carbonates, concretions, clay or organic coatings on peds,
presence of coarse fragments, and mineralogy. All of these
characteristics and features are combined to provide the
information for the interpretation of archaeological sites.
The occurrence of fecal pellets (Figure 11 ) was noted in several
profiles at al-Mudaybi’. Horizons with nearly 70-90% fecal
pellets occurred commonly at depths around 50 to 60 cm. This may
be an indication of more rainfall during the deposition of
sediment and subsequently an increase in population of the small
mammals that inhabited the site. |
