Wednesday, March 16, 2011

Final Lab: To Dig or not to Dig?

Introduction:
Beginning with its roots in antiquarianism, archaeology has progressed throughout the past two centuries, shifting from a discipline concerned primarily with physical remains to a discipline that aims to reconstruct past societies and human behaviors.  Archeologists seek to reconstruct past behavior through the examination of physical remains, whether in the form of artifacts, features, sites, or regions.  The study of archaeology has taken root throughout the majority of the world and there are still many places left to be uncovered.  GIS is fast becoming an important tool for helping to reconstruct past societies.  Much of the GIS work that is done is based on specific sites and regions, however archaeology can benefit from GIS on a global scale.  My first goal in the implementation of this project was to incorporate GIS with worldwide archaeological information to gain understanding of the time depth within the study of archaeology.  Geographically examining where archaeological work has been done in the past aids in proposing where archaeological work should be done in the future.  Additionally, archaeologists need to understand the specific environment in which they are working in order to understand what sort of features will preserve and which will decay.  My second goal was to find the environments that are most suitable for preserving archaeological materials and display them geographically so that archaeologists can then interpret where to look and was to avoid.  While both of these aims are helpful, they are still not sufficient to understanding where to dig.  My ultimate purpose in the following project was to combine the information I gathered about the locations of archaeological material and density of dwelling throughout time with the suitability of the environment to preserve the archaeological materials in order to discover the most suitable places to dig and study with the most success is the ultimate purpose of the following project.

Methods:
To begin this project, I needed to find the correct data.  Since the field of archaeology is only just beginning incorporate GIS technologies into their study of past remains, there is very little data available.  However, since my goal was to discover where archaeological sites are, the data was not too hard to collect.  I found coordinates provided by Wikipedia about the location of archaeological sites throughout the world, which I then created an excel file for and imported that into GIS to project.  The location of current archaeological sites is representative of where past societies were dwelling in addition to where current societies dwell.  The other data that I used were about the environmental regions of the world, provided by ESRI. 

The next step in the process was to covert the features provided in the environmental shapefile into raster, in order to perform suitability analysis upon them.   Once it was in a raster form, I was able to reclassify the environments based on their suitability in preserving archaeological materials.  I obtained this information from the text Archaeology: Theories, Methods, and Practice by Paul Bahn and Colin Renfrew (2008) .  According to this text, the best places for archeological preservation are extremely cold environments, frozen environments, marsh environments, wetlands, bogs, and extremely dry, arid, and desert environments.  The worst places for archaeological preservation are temperate climates, like most tropical regions.  Through these guidelines, I was able to reclassify the environmental layer in order to show the most suitable environments for archaeological preservation.

Following this step, I did a spatial join archaeological sites point layer with a shape file of the world containing country information.  This enabled me to spatially display the count and the density of dwelling that is known and recorded in the archaeological record.  This too had to be converted into a raster in order to perform the next step, calculation.

Raster calculation takes the number that is assigned to each cell on a given map and uses a mathematical function (in this case, I added) to combine with the cell that spatially corresponds to on a different raster map.  The raster calculation of the environmental suitability layer and the density of dwelling layer were next.  I implored the spatial analyst toolbar and weighted the density of the dwelling layer slightly higher, in order to counteract the extremely high preservation quality of extremely uninhabitable areas, like Antarctica.   I reclassified the results in order to make the data more easily understandable and divided it into 5 categories: least suitable, unsuitable, somewhat suitable, suitable and most suitable.

I then thought it would be important to display which continents had the most suitable places to dig and discover more archaeological information about so I created a graph based on the above data that I had gathered and spatially displayed.  I used the graph maker in the tool bar and displayed my results of the raster calculation for the variety of sites throughout the world.

Additionally, it is important to consider how the layout of the maps and their constituents will be displayed on the final output.  For a frame a reference, I inserted a globe with the locations of archaeological sites throughout the world.  I also incorporated the theme of archaeology into the color scheme, using earth tones to tie the elements together.  Also, I aimed for my display to be hierarchically based through the size of each of the features and also arranged in a way that is aesthetically pleasing as well as revealing of the relative importance of each element.

Results:
The methods that I implored were highly valuable and helpful in addressing the main purpose of this project, that being the locations in which archaeologists should be digging.  Interestingly, many of the places that had the best preservation of archaeological material were places that were completely inhabitable.  The relationship between good preservation and density of dwelling seemed to be inversely related. However, there did seem to be a good amount of evidence suggesting where some very good, suitable places were to study and gather information about the archaeological record.  For example, some highly suitable places to dig as revealed by this study are in Mexico, parts of Africa, and in the American southwest to name a few.  Some unsuitable places are the northern parts of Canada, and Russia as well as the tropical regions of northern South America. 

Another result of this assessment of where archaeologists should be digging was the visual display of the wealth of information about the archaeological record according to the above methods that is offered by continent.  This graph reveals the continents that have the most archaeological materials as well as the best environment suitable for preservation.  According to this graph, the best continent to conduct archaeological research is Asia.  Interestingly, this is where much of the archaeological research has been done that has occurred in the past decade.  It is important to keep in mind however, that Asia is also the largest continent and therefore its sheer size and prevalence of past material could also skew some of the results.

Conclusion:
I used GIS and many of its important functions and features in the quest to find the best preserved and most prevalent amount of information in the archaeological record.  The importance of understanding this information in a geographic context is extremely important as it does not just display where the best site are, but it is also able to be spatially referenced.  Archaeologists can look at this map in GIS and locate the exact coordinate of past sites and find the exact location of further archaeological projects that have not yet been undertaken.  I created these maps in a hope that they could be used as a tool for archaeologists in the future but also as a way to show the importance of GIS in archaeology.  Many archaeologists are worried about the limitations of GIS and how it can skew data and create misunderstandings about the archaeological record and GIS has not been as actively incorporated into the study as it has been in many other social sciences.  There are many further applications of GIS with archaeology, most having to do with reconstructing past societies and also making predictions, through the predicative model feature in ArcGIS about how exactly humans in the past shaped their environment.  The possibilities of GIS within archaeology are endless; the field of archaeology just needs some GIS experts to help them move forward into this impressive technology.

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