Fabric Analysis on the Spatial Distribution of Artifacts from the Ryan-Harley site
Morgan Smith is a Ph.D. fellow within the Anthropology department of Texas A&M University who is an avid SCUBA diver and rock climber; naturally we got along well. During the last year of my undergraduate, Morgan acted as a mentor while I assisted him with his project by preforming some data analysese using Geographic Information Systems (GIS).
Smith's dissertation revolved around a paleolithic archaeological site located on the Ryan-Harley arm of the Wassica river in northern Florida. The Ryan-Harley site is located on an eastern bank and is completely submerged by the river's anabranching fluvial movements. During the summer of 2015, Smith and Dr. Michael Waters of the Center for the Study of the First Americans led an underwater excavation to retrieve artifacts. More than 3,800 objects were recorded, cataloged and brought back to the lab to be cleaned and studied in detail. Of the artifacts, the two categories that held the most interest were bones and lithics.
The hypothesis behind the Ryan-Harley site postulates that this location was once used by nomadic hunters as a sort of temporary camp ground while in pursuit of wild game. To reaffirm the hypothesis, artifacts in the form of bones and the lithic flakes were found littered among the site, leading many to believe that this site was a pre-histoic midden. In this context lithic refers to stone (mostly chert) that was used in the flint-knapping process to create stone tools and weapons; bones are mostly detritus that was left behind from animal carcasses. Whatever the initial speculation, Smith could not rule out other possibilities so easily, one alternative idea being that the artifacts were found in their post-deposition locations prior to some meteorological or hydrological event they were originally deposited up river. To test the null hypothesis, I created a series of maps using ArcGIS and ArcScene to model the locations of the artifacts found in-situ and investigate the likelihood of being post-deposited by some natural process rather than culturally.
To investigate this we mapped the strike and the dip angles for each artifact and followed two assumptions: if a group of objects are all deposited by a natural process (meteorlogical, aeolian, hydrological) near the same area, we would expect them to all exhibit a near uniform pattern among the dip and strike angles. While if the objects were deposited by cultural means (in this context, early Americans) we would expect their strike and dip angles to be more random with less of a discernible pattern.
Directly below is the full report, followed by the poster presentation with a brief synopsis.
Figure 1 and 3 - The Ryan-Harley site is located on the northwestern bank of a small island located in the Wacissa river of northern Florida. The site is now submerged due to an increase in water level since the Pleistocene and the river's anabranching fluvial movements; to excavate the team used SCUBA equipment.
Figure 2 - The top map shows every artifact that was recorded and taken from it's original location; each dot represents a single artifact with color identifying which category it falls under. The two main categories of interest (and the majority of the artifacts found) were bones and lithics. The bottom shows just the two categories and is meant to represent that there does not seem to be an obvious pattern based solely on the type of artifacts. Note that the rectangular shape the artifacts are found around was due to the setup of the work site, not a special pattern of distribution.
Figure 4 - The two panels show bone and lithics artifacts which are represented in two different ways. The color of each artifact represents the depth it was excavated at, while the arrow shows the strike. The strike is the orientation of an object on a horizontal plain. First making general observations we can see that the further north from the island the deeper the water is. Looking at the strike orientations for either the bones or the lithics, there does not seem to be a pattern that is excepted of materials that were deposited by fluvial mechanics. If an increased in river volume or velocity were to post-deposit these artifacts, we would expect to see some generality in the strike orientations and not the randomness we see. (Note that one map that was not included in this poster was a compass-rose diagram which showed the frequency of strike and dip orientations which concluded that the direction among the artifacts were near random).
Figure 5 - The two panels represent the same artifacts from Figure 4, however instead of strike we are looking at the dip. The dip angle is the angle of an object relative to a vertical axis; in this project the dip could only be recorded relative its strike angle. Each dot's color is an indicator of the severity of the dip angle (lighter yellows are flat or 0 degrees, darker reds are high or 90 degrees). Based on the two panels there is also no discernible pattern among the dips either.
Again, if the objects were to be deposited by some natural event we would expect to see some sort of pattern or theme to the strike and dip angles. However, based on these data we see no recognizable pattern to display this. Because of this, we falsify the alternative hypothesis and continue to test the possibility that there is some pattern among the deposited artifacts. In the future, investigations will build on this project and compare the weights, the clast size, and include spatial statistics on each artifact to determine if there are any patterns.
The poster (above) was the final draft for this project; during spring of 2016 I presented at three undergraduate research conventions and was awarded at each:
Texas A&M University Student Research Week 2016. 2nd place.
Texas A&M Anthropology Student Research Week 2016. 2nd place.
Society for Underwater Technology TAMU 2016: Frontiers in Underwater Technology. 3rd place.
Check the Texas A&M Anthropology newsletter for more information.