Digitizing Archaeological Maps and Data

This week's assignment was pretty interesting and one that should be pretty useful for anyone working in a region that has had a lot of fieldwork in previous decades, specifically prior to computerization of records.  The general idea was using older documents from a Valley of Oaxaca (Mexico) survey, digitizing and geoprocessing those maps onto an ArcGIS basemap, digitizing various aspects of the maps (sites and land use) and then using data from the original surveys to do analysis.  The first map (above) shows my three assigned grid (N6 E4, N6 E5, and N6 E6) geoprocessed onto a digital topographic map and also the larger Valley of Oaxaca survey area.

The biggest challenge was getting the larger survey map geoprocessed onto the base map.  My original base map selection contained far too many political objects and the topographic features were hard to see and match up with the survey area scan.  I did find a base map that seemed to have fewer objects cluttering the topography although it would be nice to fine a base map that was just topographical without towns, roads, etc.  Once the main survey scan was in place, it was relatively simple matter to geolocate the assigned grids.  The corners matched up quickly and easily and there seemed to be good correspondence, particularly with the soil type maps.

The second part of the lab involved creating an individual map for each of our assigned grids (below). For these maps, we digitized the site collection areas as polygons and captured the cultural period data from field notes.

The biggest challenge was initially understanding the original drawings.  However, once I entered “field note-taker” mode, it was pretty easy to understand how they were labeling each collection area.  Creating the collection area polygons progressed fairly quickly though there were some annoyances with polygons closing themselves too early and the stop/edit attribute table/delete bad polygon/start editing again process.  I used label classes to deal with the multiple cultural periods per collection area.  Some areas are quite crowded and therefore clutters.  Overall, I was pretty happy with the end result.

Finally, the grad students continued on to join some additional site data to the existing digitized collections for a specific cultural period.  I didn’t have any IIIB artifacts in my three assigned grids, so I used IIIA (of which I had a lot) to demonstrate the join to the additional data table.  The join was quite straightforward and after segregating IIIA collection polygons to their own layer, I simply adjusted the symbology to use the joined lopop field and appropriately color grade the sites based on their estimated low populations.