Thursday, June 25, 2015

Vacuuming the pool: The Bomba Method

The ability to improvise and dramatically change plans on the fly is paramount when performing any type of excavation. This is especially true when a method not considered to be part of the dogma of archaeology is necessary for excavation. When X-ray diffraction (XRD) test results revealed the mineral composition of the sand in the Picota Pool was overwhelmingly dolomite limestone, it was apparent this sand was indeed natural and from Palenque. A combination of carbon dioxide outgassing and constant spring water movement left an approximate 10 cm layer of powdered dolomite. With this in mind, we are now able to vacuum the sand out of the pool in order to expose the floor and actually understand its makeup.

At the beginning of the 2014 season, it was our intention to block the drains connecting the pool to the aqueduct and remove the water in order to perform wet excavations rather than doing it underwater. Once we figured out the Maya of Palenque dug into the bedrock to expose the water table, we realized our semi-trash pump method would not work. Some strategizing and adaptation then led us to scooping out mud and debris, which then exposed this sand-like substance. Left untouched for a year, the jungle had taken over and covered much of the white powder that lined the pool.

In 2015, we once again had to get creative. The “Bomba Method” (Bomba is Spanish for “pump”) has become our main source for discovery this season. After being quite discouraged over what seemed like a waste of eighty pounds of equipment in 2014, it was rather gratifying to be able to put it use this year.
The first challenge was to hold the violently vibrating pump in place. Our Maya workers, Andrés and Ricardo, who come from the village of Naranjo, threw together a platform for the pump to sit on and tied it to a tree just uphill. As is shown in the video, the person operating the pump stirs up the sand and then pauses, guiding it into the hose. When debris builds up on the hose nozzle, the operator must then brush it off in order to avoid clogging. This unique method has helped us determine that the floor was simply bedrock weathered down to small rock fragments. It goes to show that the indoctrinated technique is not always the clear-cut solution. As we have found out, if you want to answer research questions in the field, it is necessary to rely heavily on innovation and resourcefulness.

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