Review by: Melissa V. Eitzel
On Wednesday November 18th was GIS day. The Geospatial Innovation Facility (GIF) celebrated it at Berkeley by co-hosting a series of talks (and refreshments!) with the Bay Area Automated Mapping Association (BAAMA), the local professional GIS organization. One of the talks was endorsed by Indigenous Mapping Network, given by Ruth Askevold of the San Francisco Estuary Institute, on reconstructing historical California landscapes and the concepts of historical ecology. Such study is important not only because these landscapes have been and are very dynamic and complex, but also because native peoples have managed the land for many centuries before Europeans arrived, and reconstructing the pre-European landscape can lead to a better understanding of those management strategies. Many of Ruth’s examples for this talk come from one of SFEI’s projects in Contra Costa County in the Bay Area (one county over from Berkeley).
Ruth demonstrated the different kinds of historical data collected in the first phase of a project, a process she referred to as “a giant vacuum cleaner;” sources include museums, libraries, historical societies, and the like. I was personally impressed by the wealth of information in the examples she showed to us, including some information on indigenous peoples and places. I was also impressed at how one could geo-register these old maps – that is, place them on the globe and match them up with modern maps. She showed an example of a dense chaparral patch which is where the town of Oakley in Contra Costa County is now: the feature appears consistently on many of the old maps and with some creative sleuthing, they were able to determine what it was. Different sources of data are available from different times; early explorers’ accounts depict some early features of the land, and then later as surveyors began “chaining the land” (a powerful phrase, referring to the use of chains of fixed length to measure distances on the land), their detailed accounts provide a rich source of data for reconstruction of the historical landscape. Ruth also points out the artificial nature of the township and range system, including the inability of even the most determined surveyors to map the rugged terrain around Mount Diablo in Contra Costa County (in their records, there is simply an empty spot east of the mountain). All maps are made with subtle biases at least subconsciously (and sometimes consciously!) and historical maps are no different, so care must be exercised in interpretation.
Some of the data sources are old diseños, or sketches prospective landowners were required to send to the Mexican authorities in order to lay claim to the land. Some of the data are the surveyors’ records as mentioned above; and some of the sources are old aerial photographs. The project stitched together more than 500 photographs to cover Contra Costa County and located the traces of old stream channels using in part the historical aerial photos created using the photogrammetry software in ERDAS, a remote sensing imagery processing software. She showed a display of all the data together, a profusion of information which is hard to interpret all at once, and described how ideally each site has many sources; she then showed us the land cover map derived from those many sources.
Ruth finished her talk with a quick review of several other projects and interesting features they have discovered throughout California: a wetland in Ventura, extensive oak forests, and fish ponds which might have been made by humans (the topography would have predicted that they would have been filled in). Many of these features raise questions about how Native Californians would have managed these features, including the dense chaparral which is now Oakley. While Ruth’s talk did not answer specific questions about Native management, they showed, as she put it, “Clues on a Map” and are exciting hints of how people interacted with the land before European influence. Perhaps these clues can inspire further conversation with elders who may retain knowledge of these management patterns, or perhaps other historical documents may shed some light on observations of Native management.
It was an exciting talk and we are pleased that Ruth could come and share it with us tonight. The talk was very well attended – I hope that our local GIS practitioners attending GIS day got a chance to think about the history of the landscapes they work with every day, and the importance of Native peoples in mapping, as well as meeting some of our local IMN chapter members.