Case Study
Tell Ahmar (Til Barsib)
City Wall and Monumental Architechture
See also: - Summary page
- Urban Zone - Isolated
Farmstead - City Wall Resistance Data
With Magnetic Overlay
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Until this survey, the location of the western portion
of the city wall was unknown. This shade plot shows the city wall
and a zone typified by monumental architecture just within the wall.
On the smaller image, anomalies associated with architectural
features are indicated with colored lines. The wall (yellow)is thought
to be constructed mainly of large basalt blocks. Buildings in this
zone are large, and often incorporate basalt or fired brick (orange)
in their construction. Mud brick or limestone (dark blue) are also
used. An isolated linear low (light blue) appears outside the city
wall. This type of feature is often associated with presumed farmsteads
outside the city wall.
Basalt building stone, fired brick, and rather massive
pottery are all common components of the archaeological deposits
at Tell Ahmar. These materials have a remanent, or permanent magnetic
field which appears in the data as a bipolar (having both a positive
and negative component) anomaly. The magnetic signatures can be
confused with that of ferrous metal. It is therefore not possible
to always distinguish bipolar features of ancient origin, but the
pattern or configuration of many of these anomalies indicates that
they are ancient in origin.
Mud brick or limestone architecture appears as subtle
magnetic lows, because these materials have a lower magnetic susceptibility
than the surrounding soil.
Because the soils have a high magnetic susceptibility,
small scale topographic variation can produce rather strong anomalies.
Irrigation ditches and alternating rows and furrows cause anomalies
in this survey area which are often stronger than those associated
with ancient architectural features, but can be distinguished by
their patterning.
