|
Geologic Materials One of
the major contributions by geoarchaeologists (earth scientists
working in archaeology) is to identify the geological materials
at an archaeological site and in the general study area. The
geology of a site has an important function in providing the
parent materials for soil formation and in supplying natural
consolidated materials for building stone and many other uses.
On the Karak Plateau, for example, many bowls and implements
were made of volcanic rock (basalt) that occurs in many
localities of the study area.
 The Karak
Plateau has a variety of geologic formations including
limestone, basalt, and unconsolidated wind-blown silts (loess).
In numerous localities around al- Mudaybi’, the most pronounced
rock type is the Pleistocene basalt as illustrated in Figure 3.
There are at least four distinct basalt flows on the Karak
Plateau and most are believed to have been deposited during the
Pleistocene (last 2 million years). Weathering of basalt is
noted on several exposed road cuts (Figure 4  ) and shows the
disintegration of basalt usually as a weathering rind around
exposed boulders. Basalt has a special interest in this study as
a result of its use as a common building stone and for grinding
bowls, in addition to its location at al-Mudaybi’ at the base of
the archaeological excavations.
 Limestone is
the dominant rock type on the Karak Plateau and provided much of
the building stone for construction of forts and towers.
Limestone outcrops are common on the steeply sloping landscapes
(Figure 5) and valley floors (Figure 6 ) where erosion has been
severe. Figure 6, south of Mahai, illustrates the outcroppings
on these landscapes. The many limestone outcrops and shallow
soils occurring on significant amount of landscapes on the Karak
Plateau limit agricultural production in these areas. This is
the reason that loess is of such importance as a parent material
in many regions of the study area.
Figure 7
illustrates the
relationship of the thicker loess deposits on the lee slope and
the potential agricultural value of loess compared to the upper
slope where shallow areas of soils occur with numerous limestone
outcrops. Unfortunately, however, loess is one of the erosive
types of soil and can result in areas of deep gullies and thin
soils as seen in Figure 7. Loess is the parent material for the
more productive areas on the Karak Plateau and especially when
combined with more abundant rainfall. Loess was deposited in
several sequences on the study area;
Figure 8
shows a road cut
east of Karak illustrating thick loess deposits with three
paleosols in the sequence. Deposition probably started in the
Pleistocene with secondary deposition occurring even today in
the region. |
