Monday, July 1, 2013

A Summer of Analysis and Report-Writing

Some of you may have noticed the lack of blog posts for the summer field season of 2013...the reason is that we've taken a summer off to finish analyzing our finds from the 2009-2012 field schools.  But don't worry, we're planning to return to Mission Escambe in the summer of 2014, with a finished 4-year report in hand and a specific plan to fill in some of the gaps in what we've already learned about the site.

And please take the opportunity to visit the 2013 UWF summer field school web sites, including the UWF Maritime Archaeology Field School Blog, YouTube Channel, and Facebook Page, and also the UWF Campus Survey Field School Facebook Page.

Below are some pictures from the ongoing labwork relating to the mission dig.

One major task of labwork is to digitize the field maps of plan views and profiles for all the excavation units.  The picture above shows Michelle Pigott working on re-scaling and combining original drawings.  Michelle has also spent much of the summer conducting detailed metric analysis of mission-era Native American ceramics from Escambe, which will form part of her own thesis project.

Once the maps are digitized and cleaned up a bit, they are then entered into a Geographic Information Systems (GIS) database, where they are spatially referenced so that we can examine all the map information from different units together.  Above, Jennifer Melcher works her magic on the computer.

Continuing artifact analysis includes work on European trade goods by Danielle Dadiego, above, for her thesis project exploring the role of Mission Escambe in the colonial economy of 18th-century Pensacola

A major task of this summer's work has been to complete the processing of flotation samples taken during the past four years, most of which were added last year (2012).  Michelle Pigott, above, has spent a number of days working to reduce the huge volume of dirt into small bags with light and heavy fractions, following up on earlier work this winter and spring by Lauren Walls and Morgan Smith (see previous blog post).

One of the more interesting pieces of equipment that was acquired not long ago by Dr. Ramie Gougeon in UWF Anthropology is a 3-D laser scanner, which can create three-dimensional scans of artifacts or other objects, such as the late prehistoric potsherd pictured above.

The image above shows the raw scan on the computer screen (yet to be "cleaned up" of additional elements such as the platform and arm) with the original object in the background.

The lead bale seal above was scanned twice at highest resolution in order to cover all points on the surface.

The final scan of the seal shows fine details such as the lettering on the stamped surface, likely corresponding to the maker of the items being sealed (probably cloth) and perhaps also the measurement or some other designation for the item.

Saturday, January 26, 2013

Winter update: flotation samples from Mission Escambe

Thanks to extensive work this past fall by UWF grad student Lauren Walls (whose thesis project focuses on prehistoric subsistence at the Thompsons Landing site on the UWF campus), our new flotation system is in full operation, and soil samples from Mission Escambe are now beginning to be processed. With the help of student Morgan Smith, this past Wednesday we used the system to process four soil samples in order to extract lighter-than-water charred plant remains from excavated samples taken at the site in 2012 (and many more remain to be done from previous years as well).

The photo-essay below will provide an overview of how flotation is done, and shows that we are continuing to work on different aspects of the Mission Escambe project year-round. Artifact processing is nearly done from the 2012 season after a fall full of labwork, but until now, our many flotation samples have been awaiting attention. We hope to learn many new things from this process, most notably to include detailed evidence about crops and other plant foods used at Escambe, as well as the range of woods used for architecture and heating at the site.

The first and last step in flotation is proper record-keeping, which involves creating a record of precisely which samples have been processed, and attaching waterproof labels to each portion of the processed sample (both the light and heavy fractions, noted below).

Since the soils at Mission Escambe are so full of clay (they are alluvial soils alongside the Escambia River), each soil sample has to be deflocculated by soaking the soil in water and adding baking soda in order to help separate the tiny clay particles from one another and thereby release charred wood samples so they can float to the surface of the water.  Below are Lauren and Morgan gently stirring the sample.

Some charcoal particles immediately float to the surface and are poured off into a strainer to be incorporated into the light fraction of the processed sample.

Once the rest of the deflocculated sample is poured into the flotation tank, the sieve just below the water surface captures everything, including pebbles and artifacts and charcoal fragments that are heavier than water, as well as any additional particles of charcoal that will be released upon further soaking and agitation by tiny jets of water projecting upward from just below the sieve.  Gentle agitation by hand helps free these particles, which then flow on the surface of the water into another sieve which captures them as the light fraction, as the water falls through and below.

Once the sample has been thoroughly processed, the larger sieve is lifted out from the water in the tank, revealing all the artifacts, pebbles, and small rocks that may be present, including charred plant remains that were too heavy to float away.  This constitutes the heavy fraction of the flotation sample.

Both the heavy and light fractions are then placed in rectangles of curtain shear or other light cloth in order to be able to dry them for later processing and/or storage.  Below is the heavy fraction.

The light fraction is substantially smaller and lighter, consisting only of those particles (and sometimes tiny modern rootlets) that floated to the surface of the water and were caught in the sieve on the side of the tank.

The two fractions are then tied up with their appropriate labels...

...and hung up to dry.

This entire process results in a series of paired light and heavy fractions that can be examined with a microscope to sort out the assorted plant remains into their various types and individual species, allowing a remarkable glimpse into the daily lives of Mission Escambe's inhabitants.