An Unexplored Realm in the Heartland of the Southern Gulf ... - Famsi

of basalt, but instead, a body of stone placed in a fashion similar to the “Massive
Offerings” of serpentine at La Venta (Drucker et al. 1959:127-133).
The coherence, or continuousness, of this anomaly is remarkable. To produce the
anomaly associated with Structure 84 would require that the individual stone blocks in
this structure were deposited together and in the same orientation. In other words, each
individual block of stone would have been placed into the ground at El Marquesillo
maintaining a similar orientation with respect to the magnetic field and in respect to the
other blocks in the structure. The constructors of this feature had literally replicated the
same pattern and orientation of the stone as it was in its original source matrix. Evidence
from the Gulf Coast and other Formative period sites demonstrates that the inhabitants
were acquainted with the principles of magnetism and the presence of magnetic poles
within basalt (Breiner and Coe 1972; Carlson 1975; Fuson 1969; Guimarães 2004).
There are other anomalies that are associated with architectural features. Positive
and negative anomalies with peak-to-peak amplitudes of 90 nT are associated with
Structure 83 and another with Structure 86. These anomalies appear to be produced by
basalt blocks located beneath the structures. In addition, there are two types of random,
isolated anomalies found throughout the site. The primary difference between these latter
types is their size and magnetic susceptibility. The smaller anomalies have a peak-to-peak
amplitude of approximately 100 nT, while the larger ones have an amplitude of 150 nT.
The smaller anomalies may indicate hearths and the larger ones ceramic kilns that may be
spatially related to the concentrations of ceramics recovered in the surface collection and
observations of quantities of potsherds along the exposed river cut bank. Overall, the
results confirm that all the individual anomalies at El Marquesillo present a high level of
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