Saturday, December 10, 2011

Weekend Archaeology Pics

It's the weekend so I thought I'd share a picture or two from a site I worked on in Southwestern Pennsylvania
     The first photo is of the field crew troweling down the floor of the main excavation block in order to get a "clean" surface examine for any possible prehistoric features. The archaeologist's trowel is sharpened, like a knife, in order to cut the soil. If it were dull, the delicate soil layers would smear together. 

     I have always valued the connection between archaeology and the community, and here we have two volunteers Ken Gayman and Carl Maurer. Both of these gentlemen are members of the Society for Pennsylvania Archaeology, Mon/Yough Chapter #3. Ken is clearing soil from around a stump's roots, before it can be removed. Carl is screening for artifacts.   

     In this photograph you can see two more members of the Mon/Yough Chapter #3 analyzing artifacts in our lab located in the Monongahela River, Railroad, and Steam Museum in Brownsville, PA. Don Rados and Jim Barno are analyzing each individual flake from the site above. We recovered more that 8,000 Native American artifacts and flakes from their tool production. 
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Thursday, December 8, 2011

Establishing a Site Grid

Hello Everyone,

     A question that I often get when people stop by and visit a site that I'm excavating is, "Why do you dig square holes?" I'll look around the site for a minute, observing all of the different squares in various forms of excavation and think to myself about how much archaeology is art, well designed art that is. "Imagine yourself standing on a giant sheet of graph paper", I explain. 
     So I will explain to the rest of you as well! In order that we know exactly where every artifact comes from when we excavate, it is important to keep control by strictly recording their position in the ground. Before an archaeological excavation, the most important tool in the archaeologist's tool box isn't a trowel or shovel, it is the datum point. The datum point is simply the starting point for the grid that will be laid out over the site, using a series of nails and string, to help us keep track of where those artifacts came from. 
     The datum point is arbitrary, we are archaeologist place it where we think we will get the most squares to excavate to cover a site. Often times, we use some type of survey equipment and a known point, say on the corner of something that isn't going to move, like a bridge, or USGS (United States Geologic Survey) Benchmark point and triangulate it into our site datum. 
     Once the site datum is established, I like to pound in a wooden stake or piece of metal re-bar, an archaeologist can start to think about his grid. Here in the US, we use the metric system for prehistoric sites, and the Imperial for historic sites (people build their houses and buildings here using feet and inches). The smallest square we can have for grid during a site excavation is 1-meter. I like to use the 2-meter square. So lets try to make a grid for a hypothetical site.

1) Establish a datum and give it a number denoting an X and Y axis.We are going to work in Northings and Eastings. So our datum will be, North 100 E100 represented as N100 E100.
2) On my grid, I use the South West corner of each square as the Unit Datum.
3) That means the next unit to the east is N100 E102 (Remember we are working in 2-meter units)
4) If we move north on our grid, it would be N102 E102
5) If we move south on our grid it would be  S102 E102    

Here is an example of a grid that we might use:

     So that was a quick lesson on setting up a grid for excavation! On a final not, we use large nails for the four corners of each square and attach string around it to make a neat square and as a digging guide. Here is an example showing surveyors pins marking the corners of a excavation test unit:

Have a great day folks! 
P.S. Grid map example was created with LibreCAD and Inkscape software.

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Wednesday, December 7, 2011

Archaeo-Porn of the Day

Today I've decided to post some pictures of the excavations that I conducted for my dissertation research in Brownsville, PA. These few pictures are from a house site and show the remnants of 
the foundation of this once prominent residence. I've called this the Michael A. Cox House. He was a very prominent steamboat captain, banker, and investor in the small town of Brownsville in the last quarter of the Nineteenth Century. 

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