Cargo Hold Excavation


The ECU field school completed work at the end of July, 1992. The silt barrier was left in place to protect the next phase of the investigation. SJAEI conducted a limited test excavation in the forward cargo hold to assess the condition, distribution, and type of material inside. The space was highly confined and contained a high concentration of cultural material.

SJAEI's excavation took place over a six week period from August 8 to September 19, 1992. Volunteer divers used the SJAEI dive platform and surface supplied air equipment. Direct physical and communication links to the surface enhanced diver safety while working in the cramped, obstructed cargo hold. Activity in the hold stirred up sediment, restricting and often eliminating all visibility. The communications equipment allowed divers to relay descriptions and measurements to the surface for transcription and later annotation.

The hatch coaming corners provided four known datum points to record internal provenience. The excavation proceeded vertically in the square defined by the hatch except where material protruding from the wall had to be avoided or removed. In consideration of the difficult working conditions, offset recording techniques were utilized for their simplicity and because of the excavation's limited a real extent. Measurements were taken from tapes stretched along the port and aft sides of the hatch. Vertical measurements were taken with a weighted tape measure acting as a plumb bob and by using a pneumatic depth gauge calibrated in tenths of feet. Due to fluctuating tidal levels, the pneumatic gauge was calibrated to the current water depth before each vertical measurement. The northwest corner of the hatch opening served as datum for all vertical measurements. These measurements were taken from the top of the deck planks because the aft coaming was not attached.

Dredging inside the hold was done with a water induction dredge using a 4 in. suction hose. Suction force was controlled with the throttle of the water pump engine. Spoil was exhausted onto the river bottom outside the site area after passing through a nylon catch bag.

The provenience recording system used recovery numbers to identify lots and artifact numbers to identify individual items. Recovery numbers represent distinct artifact associations in close proximity to each other. An example would be a wooden box with artifacts inside. The box and its contents receive the same recovery number and each item receives an artifact number. Recovery numbers are also assigned to distinct concentrations of material which have no apparent associated container. The material may have fallen out of a container or the container may have deteriorated. For example, metal handle fragments from cloth bags, or "carpet bags", have been found but the fabric has completely deteriorated. The individual items from the bag may still be in close proximity to each other, forming an artifact concentration. Recovery numbers are also assigned to material found in the sediment but not associated with any artifact concentrations. In the forward cargo hold Recovery 54 designates general fill and includes material recovered from the catch bag.

Sealable plastic boxes were used to bring artifact material to the surface. There were two recovery options when an intact packing container with material inside was found. If the container was sound and not in danger of collapsing during removal from the supporting silt matrix, it was placed in a plastic box and taken to the surface for excavation. Due to the degraded nature of the wood and deteriorated iron fasteners holding many containers together, this procedure was rarely possible. Usually the container would not remain intact and was excavated in situ. It was excavated by hand and the artifacts placed in a plastic box for recovery. Once empty, the original container was then removed to the surface. Concentrations of artifacts not found in a container and loose material in the general fill were collected and placed in a plastic box or nylon bag.

On the surface, artifacts were tagged with recovery numbers and stored in water filled containers. They were then taken to the conservation laboratory where individual artifact numbers are assigned and conservation procedures implemented.

One alternative to artifact recovery and conservation has been on-site storage after documentation is completed. This is a viable option for certain artifact categories and is based on conservation and long term curation costs. On-site storage is used for non-diagnostic, redundant and badly deteriorated material that would provide little additional information after conservation. Barrel staves, tent poles and badly deteriorated timbers are examples of material placed in on-site storage. When this material is brought to the surface, it is assigned an artifact number, photographed, drawn, and described. It is then tagged and returned to the forward deck for reburial. Small objects are placed in bags made of geotextile fabric while large objects are returned individually. This technique allows items to be documented with little damage and returned to the site environment. They can be retrieved if and when there is a future need.